DS4560 Datasheet, PDF (5/8 Pages) Maxim Integrated Products – 12V Hot-Plug Switch

UVLO
CHARGE
PUMP
+5V
VREG
DS4560
+5V
THERMAL
80μA
LIMIT
EXTERNAL DISABLE
2.5V
TIMER
C_TIMER
12V Hot-Plug Switch
Block Diagram/Typical Application Circuit
+12V
V_CC
CURRENT
LIMIT
V_CC
80μA
LOAD
ILIM
R_ILIM
LOAD
R
OVERVOLTAGE
R
LIMIT
VRAMP
GND
C_VRAMP
Detailed Description
The DS4560 begins to operate when V_CC exceeds the
undervoltage lockout level, V_UVLOR. At this level, the
enable circuit and TIMER pin become active. Once the
device has been enabled, a gate voltage is applied to
the power MOSFET, allowing current to begin flowing
from V_CC to LOAD. The speed of the output-voltage
ramp is controlled by the capacitance placed at the
VRAMP pin. The load current is continuously monitored
during the initial voltage ramping (I_SCL) and during nor-
mal operation (I_OVL). If the current exceeds the current
limit that is set by the external resistance at ILIM, the
gate voltage of the power MOSFET is decreased,
reducing the output current to the set current limit.
Current is limited by the DS4560 comparing the voltage
difference between the LOAD and ILIM pins to an inter-
nal reference voltage. If the output current exceeds the
limit that is set by the R_ILIM resistor, the gate voltage of
the power MOSFET is decreased, which reduces the
output current to the load.
When the output power is initially ramping up, the current
limit is I_SCL. Once the voltage ramping is complete, the
current limit is I_OVL. The lower I_SCL current limit protects
the source if there is a dead short on initial power-up.
The DS4560 acts as a fuse and automatically disables
the current flowing to the load when the temperature of
the power MOSFET has exceeded the shutdown junc-
tion temperature, T_SHDN.
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