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

Part Name

Description

View to exact match

HA16114FP

Switching Regulator for Chopper Type DC/DC Converter

Hitachi -> Renesas Electronics 

HA16114P/PJ/FP/FPJ, HA16120FP/FPJ

Sawtooth wave VCT

Dead band VDB

Error output VE/O

PWM pulse output

(In case of HA16120)

Power MOS FET

drain current (ID)

(dotted line shows

inductor current)

Current limiter VIN

pin (CL)

VIN − 0.2 V

Example of step-up circuit

VIN

CF

RF

RCS

IC CL

OUT

Inductor

L

ID

VOUT

VTH (CL)

F.B.

Determined by L and VIN

Determined by RCS and RF

Figure 7.6

8. Setting the Overcurrent Detection Threshold

The voltage drop VTH at which overcurrent is detected in these ICs is typically 0.2 V. The bias current is

typically 200 µA. The power MOS FET peak current value before the current limiter goes into operation is

given as follows.

ID =

VTH − (RF + RCS) × IBCL

RCS

Where, VTH = VIN – VCL = 0.2 V, VCL is a voltage refered on GND.

Note that RF and CF form a low-pass filter with a cutoff frequency determined by their RC time constant.

This filter prevents incorrect operation due to current spikes when the power MOS FET is switched on or

off.

VIN

To other

circuitry

1k

200 µA

CF 1800 pF

I BCL

RCS

0.05 Ω

CL

OUT

Detector

output

(internal)

−+

IN(−)

RF

240 Ω

G

S

D

+

−

VIN

VO

Note: This circuit is an example for step-down use.

Figure 8.1 Example for Step-Down Use

With the values shown in the diagram, the peak current is:

ID =

0.2 V − (240 Ω + 0.05 Ω) × 200 µA

0.05 Ω

= 3.04 A

The filter cutoff frequency is calculated as follows:

1

1

fC = 2π CF RF = 6.28 × 1800 pF × 240 Ω = 370 kHz

19

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