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.
Monolithic Step-Down Switching Regulator Circuit diagram:
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.
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. Source Link
Monolithic Step-Down Switching Regulator Circuit diagram:
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.
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. Source Link
Monolithic Step-Down Switching Regulator
Reviewed by haru
on
October 29, 2017
Rating:
Reviewed by haru
on
October 29, 2017
Rating:
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