HA16120 RENESAS [Renesas Technology Corp], HA16120 Datasheet - Page 19

• Manufacturer Part Number: HA16120
• Description: Switching Regulator for Chopper Type DC/DC Converter
• Manufacturer: RENESAS [Renesas Technology Corp]

HA16114P/PJ/FP/FPJ, HA16120FP/FPJ
8. Setting the Overcurrent Detection Threshold
The voltage drop V
typically 200 µA. The power MOS FET peak current value before the current limiter goes into operation is
given as follows.
Where, V
Note that R
This filter prevents incorrect operation due to current spikes when the power MOS FET is switched on or
off.
With the values shown in the diagram, the peak current is:
The filter cutoff frequency is calculated as follows:
Rev.2.0, Sep.18.2003, page 19 of 37
I
I
f
D
D
TH
C
=
=
=
F
= V
and C
2 C
V
0.2 V
PWM pulse output
(In case of HA16120)
Power MOS FET
drain current (I
(dotted line shows
Current limiter
pin (CL)
Sawtooth wave V
inductor current)
Dead band V
TH
IN
Error output V
– V
1
F
F
TH
R
(R
form a low-pass filter with a cutoff frequency determined by their RC time constant.
V
CL
(240
F
IN
at which overcurrent is detected in these ICs is typically 0.2 V. The bias current is
F
R
= 0.2 V, V
=
+ R
CS
0.2 V
DB
D
6.28
)
V
Note: This circuit is an example for step-down use.
E/O
0.05
CS
IN
To other
circuitry
CT
200 A
+ 0.05 )
)
Figure 8.1 Example for Step-Down Use
1800 pF
I
BCL
CL
V
1 k
is a voltage refered on GND.
1
IN
200 A
OUT
240
IN( )
Detector
output
(internal)
Figure 7.6
= 3.04 A
CL
= 370 kHz
+
V
C
TH
F
(CL)
1800 pF
R
240
IC
I
F
BCL
Example of step-up circuit
G
V
C
OUT
D
IN
Determined by L and V
Determined by R
L
C
F
R
S
R
0.05
F
F.B.
CS
+
R
I
D
CS
Inductor
L
V
IN
CS
V
O
and R
IN
F
V
OUT