HA16120 RENESAS [Renesas Technology Corp], HA16120 Datasheet - Page 15

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

HA16114P/PJ/FP/FPJ, HA16120FP/FPJ
6. Usage of ON/OFF
This pin is used for the following purposes:
• To shut down the IC while its input power remains on (power management)
• To externally alter the UVL release voltage
• With the timer (TM) pin, to operate in intermittent mode during overcurrent (see next section)
6.1 Shutdown by ON/OFF
The IC can be shut down safely by bringing the voltage at the ON/OFF pin below about 0.7 V (the internal
VBE value). This feature can be used in power supply systems to save power. When shut down, the
HA16114 draws a maximum current (I
ON/OFF pin sinks 290 µA (Typ) at 5 V, so it can be driven by TTL and other logic ICs. If intermittent
mode will also be employed, use a logic IC with an open-collector or open-drain output.
6.2 Adjustment of UVL Voltages (when not using intermittent mode)
These ICs permit external adjustment of the undervoltage lockout voltages. The adjustment is made by
changing the undervoltage lockout thresholds V
the accompanying diagrams.
When the IC is powered up, transistor Q
and R
This V
below 2.5 V. To obtain Vref = 2.5 V, V
Since V
coefficient of approximately –4 mV/°C. Keep this in mind when designing the power supply unit.
When undervoltage lockout and intermittent mode are both used, the intermittent-mode time constant is
shortened, so the constants of external components may have to be altered.
Rev.2.0, Sep.18.2003, page 15 of 37
D
IN
in the diagram makes undervoltage lockout release at:
ON/
V
is the supply voltage at which undervoltage lockout is released. At the release point Vref is still
OFF
IN
External logic IC
= 1.4 V
operates in relation to the base-emitter voltage of internal transistors, V
OFF Pin
OFF
OFF
R
OFF
OFF
OFF Pin Control
C
R
+ R
D
Figure 6.1 Shutdown by ON/OFF
D
Off
Switch
C
ON/
On
OFF
OFF
IN
+
3
must be at least about 4.3 V.
) of 10 µA, while the HA16120 draws a maximum 150 µA. The
is off, so V
R
R
A
B
ON/
TH
TM
and V
OFF
GND
ON
10 k
3V
is 2V
To latch
TL
BE
relative to V
OFF
OFF Pin Control
HA16114,
HA16120
OFF
BE
V
, or about 1.4 V. Connection of resistors R
IN
Q
Q
I
1
IN
2
IN
Q
, using the relationships shown in
reference
On/off hysteresis circuit
3
Vref
V
IN
To other circuitry
ON
Vref
output
has a temperature
C