PSB2121 データシートの表示（PDF） - Infineon Technologies

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PSB2121

General-Purpose Power Controller (GPPC)

Infineon Technologies 

PSB 2121

Pulse Width Modulator

The pulse width modulator compares the sawtooth-voltage of the oscillator output with the input

signal at PWMP and with the voltage of the external soft start capacitor at CSS (see figure 1).

Error Amplifier

Conventional operational amplifier for closed-loop gain and phase compensation.

Low output impedance: unity-gain stable

Control Logic

The control logic inhibits double pulses during one duty cycle and limits the maximum duty cycle to

50 %.

Current Limiting

A differential input comparator terminates individual output pulses each time when the sensvoltage

rises above threshold.

When sense voltage rises to 100 mV above threshold a shutdown signal is sent to the control logic.

CMOS Supply

An integrated 6 V linear voltage regulator supplies the internal low-voltage CMOS-circuits from the

input voltage. This supply-voltage is connected to pin VEXT and has to be buffered by an external

capacitor (Cmin = 1 µF). Power dissipation of the linear voltage regulator can be reduced, if an

external supply is used for that purpose by connecting it to pin VEXT. If the input voltage at VEXT

reaches 6.2 V the internal linear voltage regulator turns off and the internal CMOS-circuits are fed

from the external voltage. In this case the input current at VEXT is approx. 0.5 mA.

Note: An internal 7.5 V Z-diode protects the VEXT input against overvoltage. The maximum Z-current

is 2 mA! So if the external CMOS-supply isn’t stabilized the input current must be limited (e. g.

by a resistor).

Semiconductor Group

10

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