AT1395

Preliminary Product Information

5-Channel DC-DC Converter for DSC

2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.

Tel: 886-3-563-0878

Fax: 886-3-563-0879

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Function Description

1. Power Converter Functions

＊

Reference voltage block

The reference voltage circuit generates a temperature independence voltage

(typical=2.2V) from the power source, which is used as reference voltage for the

IC’s internal circuitry and supply load current above 10mA to external device.

＊

Triangular oscillator block

The triangular wave oscillator is generated by timing capacitor(CT) to incorporate

each other.

The waveforms CT (amplitude of 0.3V to 0.8V), CT1 (amplitude

0.3V to 0.8V in phase with CT) and CT2 (amplitude 0.3V to 0.8V in inverse phase

with CT) are input to the PWM comparator.

＊

Error amplifier block

The error amplifier outputs controlling error signal to PWM comparator from

sensing DC/DC converter output voltage. In addition, an arbitrary loop gain can

be set by connecting feedback resistor and capacitor from the output pin to

inverted input pin of the error amplifier, in order to make a stable system.

＊

CH4 Inverting amplifier block

The inverting amplifier detects the DC/DC converter output voltage (negative)

and outputs a control signal to the error amplifier.

＊

PWM comparator block

The PWM comparator is a voltage-to-pulse width converter for controlling the

duty cycle of DC/DC converter.

Channels 1, 2 main sides, channel 3, 4, and 5: The comparator keeps the

output transistor turn on while the error amplifier output voltage and DTC voltage

still higher than the triangular wave voltage.

Channels 1, 2 synchronous rectification sides : The comparator keeps the output

transistor turn on while the error amplifier output voltage still lower than the

triangular wave voltage.