THV3543_Rev.1.00_E
ꢀ
Under Voltage Protection (UVP)
UVP is protective function which shuts down the power supply, when under voltage condition of DC/DC, VGH and
VGL caused by short circuit continues for more than a definite period of time. The internal comparator monitors the
output voltage. If the output voltage drops below a definite value, timer latch circuit starts operating (See Figure 4).
When abnormal output continues for more than 12.2msec, the device stops switching operation and goes into latch
state. If UVLO operates before the device goes into the latch state, the timer will be reset.
As to VGH and VGL, UVP detection does not operate for 3msec immediately after startꢀup sequence. Please set the
startꢀup time of charge pumps within 15msec to prevent startꢀup failure.
AMP
or
COMP
Output Voltage
Detection
ꢀ
+
VREF
UVP COMP
Timer
Latch
ꢀ
+
Vth
Figure 4. Under Voltage Detection Circuit
ꢀ
Over Voltage Protection (OVP)
OVP is protective function which shuts down the power supply when output voltage on CHꢀ1 and CHꢀ2 exceed a
defined voltage. CHꢀ1 stops switching operation, when the voltage on INV1 pin exceeds 1.5V. CHꢀ2 stops switching
operation, when the voltage on VO2_IN pin exceeds 4.13V (See Figure 5) .
As to CHꢀ2, if abnormal output is detected, timer latch circuit operates. When abnormal output continues for
2.44msec, the device stops switching operation and goes into latch state.
Output Voltage
Dtection
AMP
PWM COMP
ꢀ
OUT
+
SS
VREF
OVP COMP
ꢀ
+
Vth
Figure 5. Over Voltage Detection Circuit
ꢀ
Over Current Protection (OCP)
CHꢀ1 and CHꢀ2 have builtꢀin over current protection circuit. When load current exceeds a definite current, OCP stops
switching operation of the device. OCP operates at more than 4.0A on CHꢀ1, 3.5A on CHꢀ2.
If over current is detected continuously, low duty switching pulse is generated and that causes output voltage drop.
When output voltage drops below a definite voltage for more than 12.2msec, UVP operates and the device goes into
latch state.
THine Electronics, Inc.
Copyright© 2011 THine Electronics, Inc.
14/19
THINE [ THINE ELECTRONICS, INC. ]
