HA16114FP View Datasheet(PDF) - Hitachi -> Renesas Electronics

Part Name

Description

Manufacturer

HA16114FP

Switching Regulator for Chopper Type DC/DC Converter

Hitachi -> Renesas Electronics 

HA16114P/PJ/FP/FPJ, HA16120FP/FPJ

The oscillator frequency fOSC can be calculated as follows.

fOSC =

1

t1 + t2 + t3

Here, t1 =

t2 =

CT × (VH − VL)

1.1 V/RT

CT × (VH − VL)

3 × 1.1 V/RT

t3 ≈ 0.8 µs (comparator delay time)

Since VH − VL = 0.6 V

fOSC ≈

1

0.73 × CT × RT + 0.8 (µs)

(Hz)

At high frequencies the comparator delay causes the sawtooth wave to overshoot the 1.6 V threshold and

undershoot the 1.0 V threshold, and changes the dead-band thresholds accordingly. Select constants by

testing under implementation conditions.

Current

mirror

1.1 V

3.2 V

(Internal voltage)

1:4

CT charging

IO

Oscillator

comparator

Discharg

-ing 3IO

RT

CT

IO

External circuit

VH = 1.6 V typ

Vref

2.5 V

RA

RC

RB

Sync

circuit

SYNC

VL = 1.0 V typ

t2

t1 : t2 = 3 : 1

t1

Figure 1.1 Equivalent Circuit of Oscillator

7

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