Monolithic Step-Down Switching Regulator

L4962 is a monolithic step-down  switching regulator. It provides  output voltage of 5.1V to maxi-mum 40V, delivering current up to  1.2A to 1.5A, depending on the type  and package. The theoretical internal  functions are almost the same. The  heart  of  the  device  is  the  regulation  loop  consisting  of  a  saw  tooth  oscillator, error amplifier, comparator and  source-sink output stage.

Circuit diagram :

 Fig. 1: Circuit of switching regulator

An error signal is produced by  comparing  the  output  voltage  with  a precise 5.1 volt on chip reference  (which is zener zap trimmed to ±2  per cent). This error signal is then  compared  with  the  saw  tooth  signal  to generate the fixed frequency pulse  width  modulated  pulses  which  drive the output stage.

Fig. 1 shows circuit diagram of  the regulator. The gain and frequency  of the loop can be set by RC network  connected to IC pin 11. When the loop  is  closed  directly  by  connecting  the  supply output to the feedback input  IC pin 10, an output voltage 5.1 volt is  produced. Higher output voltages are  obtained by inserting a voltage divider  in this feedback path. the outputs over current errors generated  at  the  on  switch  are  prevented  by  the  self-start  function.  The  error  amplifier  output is initially  clamped  by  the  external  capacitor ‘Css’ of pin15,  and  is  allowed  to  rise  linearly  as  this  capacitor  is  charged  by  a  constant  current  source.

Output overload protection is pro-vided in the from of a current limiter.  When the load current exceeds a preset  threshold, this comparator sets a flip-flop, which disables the output stage  and discharges the soft start capacitor. Another internal comparator resets  the flip-flop when the voltage across the soft capacitor C3 falls  to 0.4V. The output is thus  re-enabled  and  the  volt-age  rises  under  the  control of soft start network.  If overload condition is  still  present,  the  limiter  will  trigger  again  when  the  threshold  current  is  reached.  The  average  short-circuit is limited to a  safe value by the dead time introduced  in the soft start network. The thermal  overload circuit disables circuit operation when the junction temperature is  about 150°C and has hysteresis to  prevent instability. Frequency is about  100 KHz with parallel RC network connected to this terminal.

Fig. 2: Specification of L1 

Assemble the circuit on a general-purpose PCB by using two connectors one  for  the  input  and  the  other for the output. You can also use  a  DC-DC  converter  circuit  in  place  of  the  linear  regulator  to  avoid  the  use  of transformer and also to reduce dissipation. Finally, short-circuit protection is provided for all of the auxiliary  outputs by clips, internal current limiter and thermal protection circuit. The  specification of inductor L1 as shown  in Fig. 2. It is a ferrite torroid core T-18  with a small 20 turns of 27 SWG enameled copper wire.

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Regulator for Three-Phase Generator Circuit Diagram

This regulator was designed for use with a  generator with a higher output voltage. This  type of generator can be found on some boats  and on vehicles for the emergency services.  They are really just an adapted version of the  standard alternator normally found in cars.  The field winding is connected to the 12 V  (or 24 V) battery supply, whereas the generator winding is configured for the AC grid  voltage (230 V or 115 V). This AC voltage now  has to be kept stable via the 12 V field winding. Although it’s perfectly possible to use a  switching regulator for this, we deliberately  chose to use the old and trusted 723.

The generator is a three-phase type, with the  field winding rated for 12 VDC. The output voltage of the generator depends on its revs  and the current through the field winding.  Since the output voltage is relatively high, it  is fed via opto-couplers to the 723, which is  used in a standard configuration.  The output is fed via driver T1 to two  2N3055’s, connected in parallel, which sup-ply the current to the field winding. In the prototype we used TLP620 opto-couplers. These are suitable for use with alternating voltages because they have two anti-parallel LEDs at the input. The regulation works  quite well with these, with the output volt-age staying within a small range across a wide  range of revs. 

Regulator for Three-Phase Generator Circuit Diagram

Regulator for Three-Phase Generator Circuit Diagram

However, the sensitivity of the two internal  LEDs can differ in this type of opto-coupler,  since it’s not always possible to ensure during  the manufacturing process that the distance  between each LED and the phototransistor is  exactly the same. For a more precise regulation it would be better to use two individual  opto-couplers per phase, with the inputs connected in anti-parallel and the outputs connected in parallel.

In order to ensure that there is sufficient isolation between the primary and secondary side  you should make a cutout in the PCB underneath the middle of each opto-coupler. Instead of a BD136 for T1 you could also use  a TIP32 or something similar. For T2 and T3  it’s better to use a type with a plastic casing,  rather than a TO3 case.

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Rotative Speed Regulator Borer, Driller Controller

This rotative speed regulator circuit schematic allows to control the holing speed of your borer or driller machine. This project is based on the fact that if the load grows, the voltage decrease and current increase. Use this circuit to control the speed of revolutions of your drilling mill or bench drill.

Driller controller circuit schematic

 

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Ultra Low Drop Linear Regulator Circuits Project

The circuit is a MOSFET based linear voltage regulator with a voltage drop of as low as 60 mV at 1 ampere. Drop of a fewer millivolts is possible with better MOSFETs having lower  RDS(on)  resistance. 

The circuit in Fig.1 uses 15V-0-15V secondary output from a step-down transformer and employs an n-channel MOSFET IRF540 to get the regulated 12V output from DC input, which could be as low as 12.06V. The gate drive voltage required for the MOSFET is generated using a voltage doubler circuit consisting of diodes D1 and D2 and capacitors C1 and C4. To turn the MOSFET fully on, the gate terminal should be around 10V above the source terminal which is connected to the output here. The voltage doubler feeds this voltage to the gate through resistor R1. Adjustable shunt regulator TL431 (IC2) is used here as an error amplifier, and it dynamically adjusts the gate voltage to maintain the regulation at the output.

Circuit Fig.1

With adequate heatsink for the MOSFET, the circuit can provide up to 3A output at slightly elevated minimum voltage drop. Trimpot VR1 in the circuit is used for fine adjustment of the output voltage. Combination of capacitor C5 and resistor R2 provides error-amplifier compensation. 

The circuit is provided with a short-circuit crow-bar protection to guard the components against over stress during accidental short at the output. This crow-bar protection will work as follows: Under normal working conditions, the voltage across capacitor C3 will be 6.3V and diode D5 will be in the off state since it will be reverse-biased with the output voltage of 12V. However, during output short-circuit condition, the output will momentarily drop, causing D5 to conduct and the opto-triac MOC3011 (IC1) will get triggered, pulling down the gate voltage to ground, and thus limiting the output current. The circuit will remain latched in this state, and input voltage has to be switched off to reset the circuit. 

Circuit Fig.2

The circuit shown in Fig.2 follows a similar scheme. It can be utilised when the regulator has to work from a DC rail in place of 15V-0-15V AC supply. The gate voltage here is generated using an LM555 charge pump circuit as follows: 

When 555 output is low, capacitor C2 will get charged through diode D1 to the input voltage. In the next half cycle, when the 555 output goes high, capacitor C3 will get charged to almost double the input voltage. The rest of the circuit works in a similar fashion as the circuit of Fig. 1. 

The above circuits will help reduce power-loss by allowing to keep input voltage range to the regulator low during initial design or even in existing circuits. This will keep the output regulated with relatively low input voltage compared to the conventional regulators. 

The minimum voltage drop can be further reduced using low RDS(on) MOSFETs or by paralleling them.

Source by : Streampowes

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1.5 - 35 Volt DC Regulated Power Supply Circuit Project

Here is the circuit diagram of regulated power supply. It is a small power supply that provides a regulated voltage, adjustable between 1.5 and 35 volts at 1 ampere. This circuit is ready to use, you just need to add a suitable transformer. This circuit is thermal overload protected because the current limiter and thermal overload protection are included in the IC.

Picture of the circuit:

1A Regulated Power Supply Circuit Schematic

Circuit diagram:

1A Regulated Power Supply Circuit Diagram

Transformer selection chart:

Transformer selection Guide-Table For Power Supply

Parts:
IC = LM317
P1 = 4.7K
R1 = 120R
C1 = 100nF - 63V
C2 = 1uF - 35V
C3 = 10uF - 35V
C4 = 2200uF - 35V
D1-D4 = 1N4007

Features:

• Just add a suitable transformer (see table)
• Great to power your projects and save money on batteries
• Suitable as an adjustable power supply for experiments
• Control DC motors, low voltage light bulbs, …

Specifications :

• Preset any voltage between 1.5 and 35V
• Very low ripple (80dB rejection)
• Short-circuit, thermal and overload protection
• Max input voltage : 28VAC or 40VDC
• Max dissipation : 15W (with heatsink)
• Dimensions : 52x52mm (2.1” x 2.1”)

Technical Specifications

• Input Voltage = 40Vdc max Transformer
• Output Voltage = 1.5V to 35Vdc
• Output Current = 1.5 Amps max.
• Power Dissipation = 15W max (cooled)

Note:

• It has not to be cooled if used for small powers. 28 Volt AC max is allowed for the input voltage.

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Ceiling Fan Regulator- Motor Speed Control Circuit Diagram

This is a simple ceiling fan regulator circuit diagram. It is used to control the speed of a ceiling fan. In the other words it is an AC motor speed controller circuit, as because it's control the speed of a AC motor(Ceiling Fan).  This ceiling fan regulator circuit built with few numbers of parts. The circuit mainly  based on Z0607 TRIAC. This is a low power AC semiconductor device. Generally which is used to controlling speed of low power ac motor speed. 

Circuit Diagram of Ceiling Fan Regulator : 

 

 

In this ceiling fan regulator circuit, R1=500KΩ is a variable resistor that is used to adjust the fan speed. Capacitor C1 2A104J is a Polyester film capacitor.

Pin Diagram of  TRIAC(T1)- Z0607: 

Fig: Z0607-TRIAC Pin diagram

Pin Diagram of Variable Resistor R1:

Fig: Pin Diagram of Variable Resistor

Parts List Ceiling Fan Motor Speed Controller circuit:

T1 = Z0607 -TRIAC
D1 = DB3 C312 -DIAC
R1 = 500KΩ -Variable Resistor
R2 = 37KΩ -Resistor
C1 = 2A104J -Polyester film capacitor.
M1 = Single Phase AC Motor (Ceiling Fan)-220V,50Hz

Source

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1+1 Regulator Handles Two Input Voltages Circuit Diagram

Regulator Handles Two Input Voltages circuit in Fig 1 supplies both 3.3 and 5V to transitional circuits that employ both the new 3.3V and older 5V devices. Additionally, because the regulator accepts either 3.3 or 5V inputs, you could plug it into either a new 3.3V system or an old 5V system.The circuit consists of two sections: a dc/dc converter and a double-pole, double-throw (dpdt) switch. The dpdt switch comprises a pair of dual n-channel MOSFETs (Q2 and Q3) and their associated high-side drivers.

Upon power-up, the comparator in IC2 determines the state of the circuit. The comparator’s output, IC2 pin 6, goes to the input of the MOSFET driver, IC1. The driver internally generates a gatedrive voltage 8.8V above the device’s supply voltage. This high voltage drives the appropriate MOSFETs in Q2 and Q3.

IC2 is also the heart of a flying-capacitor, buck/boost dc/dc converter. Unlike other switching-regulator schemes, this topology needs no transformers. Transistor Q1 controls this section’s output voltage, VS. When VIN is at 5V, Q1 is off, forcing the section to operate as a step-down converter. In this mode, the section produces 3.3V, which goes to the output through Q3B. Also in this mode, 5V power goes directly through Q2A, and Q2B and Q3A are both off.

When VIN is 3.3V, IC1 turns on Q1, shorting out the 140-kΩ resistor and forcing the dc/dc-converter section into step-up mode. In this mode the converter section generates 5V at VS, powering the 5V output via Q2B. Also in this mode, 3.3V goes directly from the circuit’s input to the output via Q3A. Q2A and Q3B are both off.No-load quiescent current consumption is approximately 500 μA.

Lower-frequency converters would reduce power consumption at the expense of a larger inductor. The efficiency of the dc/dc-converter section is 73% in either mode. But because this power accounts for only half of the circuit’s output power, the circuit’s overall efficiency is approximately 80% with VIN=3.3V and 86% with VIN=5V. 

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Zener Diode Circuit Diagram

Here we used the 12-0-12 step-down 500mA power transformer. The output of the transformer is supply to the bridge rectifier made of D2 , D3, D4, D5 which is use to convert the Ac supply to the DC supply. Capacitor C1 is used as a filter the DC output. We used  470 μF capacitor  but you can used any. More the value of capacitor more pure DC can be obtained. Resistor R2 of 2.2K is used as bleeder. Here you can see the transistor T1 [BC147B] and transistor T2 [SL100] are use for regulator compressor. The DC output is fed to these transistors. T1 acts as a series pass driver or a current regulator. Base bias for transistor T1 is achieved from the supply through resistor  R3 of 680 ohms  as resistor R2 of  10k is a base bleeder and capacitor C2 1 μF  filters base potential. When the test probe is fully open with no zener connected, the base potential of transistor T1 is around 32V that is across resistor R4 or capacitor C2.

Zener Diode Circuit Diagram 

Transistor T1 [BC147B] provides the base potential for transistor T2 [SL100] which acts as a series pass regulator, providing the net DC voltage equivalent to T1 base potential which is fed to the voltmeter.

Now, the voltmeter reads around 30V with no zener diode connected across the probe. When a zener  diode is connected across the test probe, the base potential of transistor T1 falls to zener diode breakdown voltage. With this, the base potentials for transistor T2 and transistor T1 become equal. The meter now shows the actual zener voltage. An adjustment of 0.6 V can be done on the meter scale by shifting the needle with zero adjustment screw on the meter.

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Solar Cell Array Charger with Regulator Circuit Diagram

Solar Cell Array Charger with Regulator circuit can be used to charge batteries from a solar cell array. The circuit consists of an oscillator, a DC-DC step-up or ‘boost’ converter and a regulator that pro-vides regulation of the output voltage.The oscillator is built around a hex Schmitt trigger inverter IC, the 40106B, one resistor, R1, inserted between the input and the output of one of the gates in the 40106 to supply charge to C3. Depending on the values of resistor R1 and capacitor C3 you’re using in the circuit, the oscillator will operate at different frequencies, but a frequency below 100 kHz is recommended. 

By consequence, the oscillator frequency should not exceed the maximum ripple frequency of capacitor C2 connected on the output. C2 should be an electrolytic capacitor with a DC working voltage larger than the desired output voltage. Besides, it should have a low ESR (equivalent series resistance). 

Solar Cell Array Charger with Regulator Circuit Diagram :

IC1A is used as a buffer, ensuring that the oscillator sees a light, fairly constant load and so guaranteeing that the output frequency remains stable (within limits, of course). VCC of the Schmitt trigger can be connected directly to the battery charged, provided the charged batter y voltage does not exceed the max. or min. limits of the Schmitt trigger’s supply voltage. This ensures the Schmitt trigger can operate even if little power is obtained from the solar cell array. 

When transistor T2 is turned on, (output from oscillator buffer IC1A is high), a collector current flows through inductor L1 which stores the energy as a magnetic field and creates a negative voltage VL1. When transistor T2 is switched off, (output from oscillator buffer IC1A is low), the negative voltage VL1 switches polarity and adds to the voltage from the solar cell array. Consequently, current will now flow trough the inductor coil L1 via diode D1 to the load (capacitor C2 and possibly the battery), irrespective of the output voltage level. 

Capacitor C2 and/or the battery will then be charged. So, in the steady state the out-put voltage is higher than the input voltage and the coil voltage VL1 is negative, which leads to a linear drop in the current flowing through the coil. In this phase, energy is again transferred from the coils to the out-put. Transistor T2 is turned on again and the process is repeated. A type BC337 (or 2N2222) is suggested for T2 as it achieves a high switching frequency. Inductor L1 should have a saturation current larger than the peak current; have a core material like ferrite (i.e. high-frequency) and low-resistance. Diode D1 should be able to sustain a forward current larger than the maxi-mum anticipated current from the source. It should also exhibit a small forward drop and a reverse voltage spec that’s higher than the output voltage. If you can find an equivalent Schottky diode in the junk box, do feel free to use it. 

The most important function of the shunt regulator around T1 is to protect the batteries from taking damage due to overcharging. Besides, it allows the output voltage to be regulated. Low-value resistor R3 is switched in parallel with the solar cell array by T1 so that the current from the solar cell array flows through it. Zener diode D2 is of course essential in this circuit as its zener voltage limits the output voltage when T1 should be turned on, connecting the solar cell array to ground via R3. In this way, there is no input voltage to the boost converter and the battery cannot be overcharged. 

Sealed lead-acid (SLA) batteries with a liquid electrolyte produce gas when over-charged, which can ultimately result in damage to the battery. So, it’s important to choose the right value for zener diode D2. Special lead-acid batteries for solar use are available, with improved charge-discharge cycle reliability and lower self-discharge than commercially-available automotive batteries. 

Finally, never measure directly on the out-put without a load connected the ripple current can damage your voltmeter (unless it’s a 1948 AVO mk2).

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Build a Car Voltage Regulator Circuit Using LM317

The car cigarette lighter socket does not only light cigarettes, but can be utilized as an electrical channel for powering tools to work on the car such as laptops and other electronic devices. The following circuit diagram shows a way of powering a two-way mobile radio using the LM317T voltage regulator.

The LM317T is an adjustable 3-terminal positive voltage regulator that efficiently provides a load current of 1.5 Amps over an output range of 1.2 V and 37 V. With reference to the circuit, it can accept 14 volts without any hassle and the voltage can be controlled easily with the use of a potentiometer, a 3-terminal resister with sliding contact. The whole circuit will contain the following components:

 Printed Circuit Board (PCB)
Resistor 1 (R1): 270 ohms
Resistor 2 (R2): 2K carbon potentiometer
Capacitor 1 (C1): 100nF
Capacitor 2 (C2): 1uF tantalum
LM317T Voltage Regulator
Heat Sink
DC Power Jacks
Green LED: Power
Red LED: Over Voltage
Zener Diode: over voltage LED switch

The zener diode switches on the over voltage LED if the voltage passing through is larger than the breakdown or preset voltage. The use of zener diode permits a constant amount of voltage and can be very beneficial for devices that inputs the same amount of voltage.

LM317T is cheaply available in the market and is very simple to integrate into several energy system to supply a maximum current or voltage.

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8-Amp Regulated Power Supply circuit Diagram

This power supply is powered by a transformer operating from 120 Vac on the primary and providing proximately 20 Vac on the primary, and providing approximately 20 Vac on the secondary. Four 10-A diodes with a 100 PIV rating are used in a full-wave bridge rectifier.

 8-Amp Regulated Power Supply Circuit Diagram

A 10,000 ^F/36 Vdc capacitor completes the filtering, providing 28 Vdc. The dc voltage is fed to the collectors of the Darlington connected 2N3055's. Base drive for the pass transistors is from pin 10 of the µ723 through a 200 ohm current limiting resistor, Rl. The reference terminal (pin 6) is tied directly to the non-inverting input of the error amplifier (pin 5), providing 7.15 V for comparison. Link

The inverting input to the error amplifier (pin 4) is fed from the center arm of a 10 k ohm potentiometer connected across the output of the supply. This control is set for the desired output voltage of 13.8 V. Compensation of the error amplifier is accomplished with a 500 pF capacitor connected from pin 13 to pin 4. If the power supply should exceed 8 A or develop a short circuit, the µ723 regulator will bias the transistors to cutoff and the output voltage will drop to near zero until the short circuit condition is corrected.

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Temperature Regulator with TIP122 Circuit Diagram

For best efficiency,make good thermal contact between the 40 ohm resistor,the TIP 122,the 3 diodes and the temperature controlled entity , the components all give off heat. We have some minor changes to the draft Roy. Roy A 4.7V zener is used in its original design and a resistor network, a range of operating temperatures of 188 degrees Kelvin to 243 Kelvin degrees C or -85 to -30 C.

Temperature Regulator Circuit with TIP122

This is fine in Cryocam Roy, but I’m afraid that many of our camera cookbook may not be able to reach a maximum temperature of Roy. That and the fact that related to the Zener 4.7V difficult to replace me with Roy Z 5.1V zener with more accessible. This diode is available off the shelf at Radio Shack. I supply the resistor network on a range of 190 K to 270 K or -83 C to -3 C I believe that most of our cameras can be maintained to -3 C and I doubt that all our cameras in a position are to be attained – 83 C, so I think that this area should be good enough coverage. I chose to use a 100k pot at some point, because I’m going to the plate with a dual digital potentiometer DS1267 replace. I do not allow for a distance, using Win245 software controllable temperature control and the 100K pot is the control loop is working is to be updated very easily. I intend to use the pot on the remaining DS1267 to replace R43 on the board pre-amp. This allows a selectable gain control software for the camera cookbook. More later.

I would recommend the maximum TEC voltage regulator and leave it there. The circuit temperature controller does the rest. You may want to perform delete on the part of the adjustment of supply voltage and tie the totally positive TEC voltage directly at the outlet of the resistors R1 and R2 in parallel with power supply stocks cookbook. There is much room is available for experiment. Roy says that his power TEC does not need to precisely controlled tension, but also be filtered and have less than 10% ripple. So, I think you no harm by not following the proportion of the supply voltage regulation will do Peltier.

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Voltage Regulator 12v to 24v using 7812

Voltage regulator 12v to 24v using 7812. What many people do not know is it possible for a voltage regulator IC to provide an output voltage higher than its actual value. One method to achieve this is by connecting the "common" terminal to the middle point of a potential divider, but the problem with this method is that the regulators IC has a small quiescent current (~ 10 mA) flowing out the common terminal to ground.

The circuit presented here avoids the problems of using the IC regulator to raise the voltage via the transistor Q1 to generate a low impedance to the common terminal video controller during the transfer of the voltage divider from a resistor divider network relatively high. The value of R3 is not critical, but should be low enough to accept the higher quiescent current without causing problems for T1.

Voltage Regulator 12v to 24v Circuit Diagram 

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Using IFR Voltage Regulator Circuit Diagram

The IFR EW a MOSFET transistor, such as transistor has higher feature high input impedance. In this circuit we used an IFR as transistor voltage regulator, which is not common, but it is very good to learn about their behavior in a circuit.

 Using IFR Voltage Regulator Circuit Diagram

This voltage regulator circuit uses a MOSFET is
IRF4905 (Vdss =-55V, RDS (on) = 0.02ohm, Id =-74A),
but any other can be tested.

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Voltage Regulator with Shutdown Digital Circuit Diagram

This is the simple project of Voltage Regulator with Shutdown Digital Circuit Diagram. This Voltage Regulator with Shutdown Digital Circuit Diagram is very interesting, it uses an LM317 regulator circuit that allows external control in a dangerous situation to turn off the regulator output in response to the trigger. The circuit is configured to output five volts suitable for all TTL logic circuits. The selected values ​​of R1 and R2 set the output to the required 5V, R2 can be changed to other values ​​other output voltages.

In unfavorable external trigger switches the transistor instantly putting R2 shorted to ground, knocking the output to zero volts.As the circuit is equipped with the function off by an external trigger, it is extremely suitable for many critical applications and for use in Arduino projects.

Voltage Regulator with Shutdown Digital Circuit Diagram

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3-A Wide-input Adjustable Switching Regulator Project

This is the simple project os 3-A Wide-input Adjustable Switching Regulator circuit diagram. The PTN78060 is a series of high-efficiency, buck-boost, integrated switching regulators (ISR) from good old Texas Instruments (TI). The caseless, double-sided package has excellent thermal characteristics, and is RoHs compliant. The PTN78060 devices operate from a remarkably wide input voltage range:

Note that the –A version supplies a negative output voltage. The devices provide high-efficiency stepdown voltage conversion for loads of up to 3 A. The PTN78060 devices are suited to a wide variety of general-purpose applications that operate off 12-V, 24-V, or tightly regulated 28-V dc power, hence are ideal for running low-voltage electronics from a very high power 24-V battery unit salvaged from an electric wheel chair and migrated into a robot.  The output voltage VO can be set to any value over a wide adjustment range using a single external resistor RSET, using the equation RSET = 54.9kΩ×(1.25V/VO–VMIN) – Rp  If pin 4 is left open, the output voltage defaults to the lowest value.

Limiting ourselves to the two positive-output regulators, for the -W version, VMIN and Rp are 2.5 V and 6.49 kΩ respectively; for the -H device, the values 11.824 V and 6.65 kΩ should be used. For the output to remain in regulation, the input voltage must exceed the output by a minimum differential voltage. Another consideration is the pulsewidth modulation (PWM) range of the regulator’s internal control circuit. For stable operation, its operating duty cycle should not be lower than a certain minimum percentage. This defines the maximum advisable ratio between the regulator input and output voltage magnitudes. For satisfactory performance, the operating input voltage range of the PTN78060x must satisfy the following requirements.

1. For PTN78060W devices supplying output voltages lower than 10 V, the minimum input voltage is (VO+2 V) or 7 V, whichever is higher.

2. For PTN78060Ws supplying output voltages of 10 V and higher, the minimum input voltage is (VO+2.5 V).

3. The maximum input voltage for PTN78060W is 10VO or 36 V, whichever is less.

4. For PTN78060H output voltages lower than 19 V, the minimum input voltage is (VO+3 V) or 15 V, whichever is higher.

5. For PTN78060H output voltages equal to 19 V and higher, the minimum input voltage is (VO+4 V).

 

As an example, the Table gives the operating input voltage range for some commonly used output bus voltages. The modules are protected against load faults with a continuous current limit characteristic. Under a load-fault condition, the output current increases to the current limit threshold. Attempting to draw current that exceeds the current limit threshold causes the module to progressively reduce its output voltage. Current is continuously supplied to the load until the fault is removed. Once it is removed, the output voltage promptly recovers. When limiting output current, the regulator experiences higher power dissipation, which increases its temperature. If the temperature increase is excessive, the module overtemperature protection begins to periodically turn the output voltage off.

The inhibit feature can be used wherever there is a requirement for the output voltage to be turned off. The power module switches off the output voltage when the Inhibit control (pin 3) is pulled to ground,for example, by a switching FET. Finally, good attention should be paid to the quality of the capacitors on VI and VO as they determine the regulator stability and overall performance to a substantial degree. Summarizing the extensive information on capacitor selection found in the datasheets, the minimum requirement for C1 is 2.2 μF (!) worth of ceramic capacitors for the –W device and 14.1 μF (!!) for the-H device. Tantalum caps are not recommended.  Similarly, at the regulator output, C2 should be at least 100 μF worth of low- ESR electrolytics. 

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Low-drop Regulator with Indicator Circuit Diagram

Even today much logic is still powered from 5 volts and it then seems obvious to power the circuit using a standard regulator from a rectangular 9-V battery. A disadvantage of this approach is that the capacity of a 9-V battery is rather low and the price is rather high. Even the NiMH revolution, which has resulted in considerably higher capacities of (pen-light) batteries, seems to have escaped the 9-V battery generation. It would be cheaper if 5 volts could be derived from 6 volts, for example. That would be 4 ‘normal’ cells or 5 NiMH- cells. Also the ‘old fashioned’ sealed lead- acid battery would be appropriate, or two lithium cells.

 

Circuit diagram : 

Low-drop Regulator with Indicator Circuit Diagram

 

Using an LP2951, such a power supply is easily realised. The LP2951 is an ever- green from National Semiconductor, which you will have encountered in numerous  Elektor Electronics designs already. This IC can deliver a maximum current of 100 mA at an input voltage of greater than 5.4 V. In addition to this particular version, there are also versions available for 3.3 and 3 V output, as well as an adjustable version.  In this design we have added a battery indicator, which also protects the battery from too deep a discharge. As soon as the IC has a problem with too low an input voltage, the ERROR output will go low and the regulator is turned off via IC2d, until a manual restart is provided with the RESET pushbutton.

 

The battery voltage is divided with a few resistors and compared with the reference voltage (1.23 V) of the regulator IC. To adapt the indicator for different voltages you only need to change the 100-k resistor. The comparator is an LP339. This is an energy-friendly version of the LM339. The LP339 consumes only 60 µA and can sink 30 mA at its output. You can also use the LM339, if you happen to have one around, but the current consumption in that case is 14 times higher (which, for that matter, is still less than 1 mA).

 

Finally, the LP2951 in the idle state, consumes about 100 µA and depend- ing on the output current to be deliv- ered, a little more. 

Sourced by: Streampowers

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