PSB2120 View Datasheet(PDF) - Siemens AG

Part Name

Description

MFG CO.

PSB2120

ISDN Remote Power Controller (IRPC)

Siemens AG 

PSB 2120

Figure 2

DC/DC-Conversion

The PSB 2120 contains a SIPMOS-transistor for power handling. Non-isolated and isolated SMPS-

configurations are possible. Logic and analog circuits are implemented in CMOS in order to achieve

low power dissipation.

The error amplifier compares the sensed voltage with a reference attached to VP and thus controls

the Pulse Width Modulator (PWM). The conversion frequency is generated by a sawtooth oscillator

which can be controlled by external RC-components (figure 4) or by an external synchronization

signal. The PSB 2120 is synchronized by the rising edge of the sync signal, whose frequency must

be 10 % higher than the free run frequency, determined by the RC-components. The SYNC-pin can

also be used as a trigger-output. As long as the capacitor of the sawtooth oscillator is discharged,

SYNC is high.

The output of the PWM is processed by the control logic and fed to the SIPMOS-transistor. The

control logic suppresses higher oscillations of the regulation loop caused e.g. in case of current limit

detection.

Semiconductor Group

7

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