HA16114P/PJ/FP/FPJ, HA16120FP/FPJ
IIN
VIN
VIN
TM
(open)
To other circuitry
Vref output
RC
To latch
ON/
Q1
Vref
10 kΩ
3VBE
GND
generation
circuit
RD
Q3
Q2
On/off hysteresis circuit
3
2.5 V
VIN ≥ 4.5 V
2
1
0
Vref
VOFF
0.7 V
VON
1.4 V
0
1
2
3
4
5
VON/
Figure 6.2 Adjustment of UVL Voltages
7. Timing of Intermittent Mode during Overcurrent
7.1 Principle of Operation
These ICs provide pulse-by-pulse overcurrent protection by sensing the current during each pulse and
shutting off the pulse if overcurrent is detected. In addition, the TM and ON/OFF pins can be used to
operate the IC in intermittent mode if the overcurrent state continues. A power supply with sharp settling
characteristics can be designed in this way.
Intermittent mode operates by making use of the hysteresis of the ON/OFF pin threshold voltages VON and
VOFF (VON – VOFF = VBE). The timing can be programmed as explained below.
When not using intermittent mode, leave the TM pin open, and pull the ON/OFF pin up to VON or higher.
The VBE is base emitter voltage of internal transistors.
VIN
RA
Current
Latch limiter
390 kΩ
CL
S
R
TM
Q
2.2 kΩ
2.2 µF
RB
ON/OFF
Vref
reference
+
CON/
−
Figure 7.1 Connection Diagram (example)
Rev.2.0, Sep.18.2003, page 16 of 37
RENESAS [ RENESAS TECHNOLOGY CORP ]
