HA16107P View Datasheet(PDF) - Hitachi -> Renesas Electronics

Part Name

Description

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HA16107P

PWM Switching Regulator for High-performance Voltage Mode Control

Hitachi -> Renesas Electronics 

HA16107P/FP, HA16108P/FP

1. Timing in Normal Operation

Timing in these ICs is based on a triangular voltage waveform. The rising edge (leading edge) defines

the deadband time tDB. The falling edge (trailing edge) defines the ON-duty control band tON. PWM

output is on in the area within tON that is bounded above by the triangle wave VCT and error output VE/O.

The following pin outputs are related to PWM control:

• CT (pin 7): triangle-wave voltage output

• E/O (pin 15): error output voltage

• RT2 (pin 8): ON-duty pulse output voltage

• OUT (pin 2): PWM pulse output (for driving the gate of a power MOS FET)

2. Triangle Oscillator, Waveform and Frequency

The triangle oscillator in these ICs generates a triangular waveform by charging and discharging timing

capacitor CT with a constant current, as shown in the equivalent circuit. The CT charge current is:

I(CTchg) = I1 =

VREF − 2VBE

RT1

The discharge current is:

I(CTdischg) = 2I2 − I1,

where

I2

=

VREF − 2VBE

RT2

In these equations Vref (reference voltage) is typically 6.45 V, and VBE (base-emitter voltage of

internal transistors) is about 0.7 V.

The deadband time is:

tDB

=

CT × RT1 × 2V

VREF − 2VBE

+ 0.8 µs

≈ 0.4 × CT × RT1 + 0.8 µs

The ON-duty time is:

tON

=

tDB

×

RT2

2RT1 − RT2

The 0.8 µs in these equations is a correction term for internal circuit delays.

The maximum ON-duty is

Du max = RT2

2RT1

The oscillating frequency is:

fOSC =

1

tDB

+ 0.8 µs

1 − Du max

1

=

(Hz)

0.8 × CT × RT12 + 0.8 µs

2RT1 − RT2

When RT1 = RT2, the maximum ON-duty is 50%, and:

fOSC ≈

1

0.8 CT RT1 + 0.8 µs

(Hz)

This approximation is fairly close, but it should be checked in-circuit.

7

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