RT2910A
Functional Block Diagram
VHV
SNS
GATE
Current
Limit
+
-
-
+
OUT
FB
1.25V
VHV
ENHV
CP_EN
TMR
-
+
0.6V
VIN
VL
LDO
+
Control
Circuitry
-
1.4V
LX
RT
VB
OC
+
-
100mV
VL
10µA
FDLY
1.25V
+
-
+
-
+
-
+
-
VREF
Reference
CS
PGND
COMP
NFB
0.6V
SFB
5VDET
1V
TMR
0.6V
GND
Fault
POK
1µA
+
-
+
-
Operation
HV Power-Switch
The HV power switch embedded an over-voltage
protection regulator that drives an external N-MOSFET
only as the pass transistor. It can operate within a wide
supply voltage range from 5V to 60V. The internal
charge pump turns on the N-MOSFET to supply current
to the loads with very little power loss. This improves the
efficiency and increases the available supply voltage
level to the load circuitry. Normally, the pass transistor
is fully on, powering the loads with very little voltage
drop. When the supply voltage surges too high, the
Voltage Amplifier (VA) controls the Gate of the N-
MOSFET and regulates the voltage at the OUT pin to a
level that is set by the external resistive divider from the
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
OUT pin to ground and the internal 1.25V reference. If
the over-voltage/current is detected, a current source
starts charging up the capacitor connected at the TMR
pin to ground .The pass transistor stays on until the
TMR pin reaches 1.45V, at which point the GATE pin
pulls low turning off the N-MOSFET.
The potential at the TMR pin starts decreasing as soon
as the over-voltage condition disappears. As the voltage
at the TMR pin reaches 0.5V, the GATE pin begins to
rise and turn on the MOSFET again.
The RT2910A senses an over-current condition by
monitoring the voltage across a sense resistor placed
between the VHV and SNS pins. An active current limit
circuit controls the GATE pin to limit the sense voltage
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS2910A-00
August 2017
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
