CS3972

Features:

· 75V_MAX, 2A_PEAK Internal witch
· 3V to 60V Input Voltage Range
· 6mA Input Supply Current
· 1.24V Precision Reference
· 40kHz Switching Frequency
· Variable Current Limit with External Voltage Clamp
· Under-Voltage Protection
· Over-Temperature Protection
· External Synchronization


Pinout




Specifications

Input Voltage Range ...................................................................................................................3V to 60V
Output Switching Voltage..................................................................................................................    75V
Voltage Transient (tr=10s, tf=400ms)................................................................................................60V
ESD (Human Body Model; R=1.5k, C=100pF) ...................................................................................2kV
Junction Temperature Range........................................................................................ -40°C to +150°C
Storage Temperature Range .....................................................................................   -65°C to +150°C
Lead Temperature Soldering
    Wave Solder (through hole styles only)......................................................... 10 sec. max, 260°C peak
    Reflow (SMD styles only) ........................................................60 sec. max above 183°C, 230°C peak
Feedback Pin Voltage (1ms transient)................................................................................................±15V


Description

The CS3972 is a 1.25A, 60V, current mode, high efficiency, switching regulator circuit. It can be configured in buck, boost, forward, isolated and non-isolated topologies, using a single-ended switch. The IC contains a 1.25A high efficiency output switch, precision bandgap reference, voltage regulator, error amplifier, oscillator, control, and protection circuitry.

Output transistor efficiency is achieved by keeping the switch in quasi-saturation when CS3972 is on. This minimizes the switch turn-off delay time and power dissipation, an important consideration for  applications with wide ranging loads.

The precision reference is internally trimmed to 1.24V, while the CS3972 oscillator frequency is internally trimmed to 40kHz. The on board 2.3V regulator powers the internal circuitry.

By keeping the voltage regulator at 2.3V, the IC CS3972 is able to operate down to 3V and maintain a constant input supply current of 6mA(typ).

Synchronization mode CS3972 is achieved by applying a pulsating VC voltage of less than 0.2V with a duration of about 0.5s to VC pin. The switching frequency can be adjusted from 50kHz to 70kHz. The IC's synchronization mode is set externally.

Protection circuitry includes a variable current limit with external voltage clamp, under-voltage and over-temperature protection.