16114FP Renesas, 16114FP Datasheet - Page 21

• Manufacturer Part Number: 16114FP
• Description: Search -----> HA16114FP
• Manufacturer: Renesas

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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:
I
I
f
D
D
TH
C
=
=
=
F
= V
and C
2π C
0.2 V − (240 Ω + 0.05 Ω) × 200 µA
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
− (R
F
F
TH
R
form a low-pass filter with a cutoff frequency determined by their RC time constant.
V
CL
F
IN
at which overcurrent is detected in these ICs is typically 0.2 V. The bias current is
F
= 0.2 V, V
R
=
− 0.2 V
+ R
CS
DB
D
6.28 × 1800 pF × 240 Ω
)
V
Note: This circuit is an example for step-down use.
E/O
0.05 Ω
CS
To other
circuitry
CT
IN
200 µA
) × I
Figure 8.1 Example for Step-Down Use
BCL
CL
V
1 k
is a voltage refered on GND.
1
IN
OUT
IN(−)
Detector
output
(internal)
HA16114P/PJ/FP/FPJ, HA16120FP/FPJ
Figure 7.6
= 3.04 A
−
CL
= 370 kHz
+
V
C
TH
F
(CL)
1800 pF
R
240 Ω
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
S
R
R
0.05 Ω
F
CS
F.B.
+
−
R
I
D
CS
Inductor
L
V
Rev.1, Dec. 2000, page 19 of 38
IN
CS
V
O
and R
IN
F
V
OUT
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