Datasheet

V =I R -
TRIP OCL DS(ON)
·
( )V-V
IN O
V
O
V
IN
2 1L f· ·
SW
¾
¾
·
R k =
TRIP
( )W
V mV
TRIP
( )
I A
TRIP
( )m
¾
TPS53114
www.ti.com SLVS887B –APRIL 2009–REVISED OCTOBER 2010
OVER CURRENT PROTECTION
TPS53114 has a cycle-by-cycle over current limit feature. The over current limits the inductor valley current by
monitoring the voltage drop across the low-side MOSFET R
DS(on)
during the low-side driver on-time. If the
inductor current is larger than the over current limit (OCL), the TPS53114 delays the start of the next switching
cycle until the sensed inductor current falls below the OCL current. MOSFET R
DS(on)
current sensing is used to
provide an accuracy and cost effective solution without external devices. To program the OCL, the TRIP pin
should be connected to GND through a trip voltage setting resistor, according to Equation 1 and Equation 2.
(1)
(2)
The trip voltage should be between 30 mV to 200 mV over all operational temperature, including the
4000 ppm/°C temperature slope compensation for the temperature dependency of the R
DS(on)
. If the load current
exceeds the over current limit, the voltage will begin to drop. If the over current conditions continues, the output
voltage will fall below the under voltage protection threshold and the TPS53114 will shut down.
OVER/UNDER VOLTAGE PROTECTION
TPS53114 monitors a resistor divided feedback voltage to detect over and under voltage. If the feedback voltage
is higher than 115% of the reference voltage, the OVP comparator output goes high and the circuit latches the
high-side MOSFET driver OFF and the low-side MOSFET driver ON. When the feedback voltage is lower than
70% of the reference voltage, the UVP comparator output goes high and an internal UVP delay counter begins
counting. After 30 ms, TPS53114 latches OFF both top and bottom MOSFET drivers. This function is enabled
approximately 1.7x T
SS
after power-on. The OVP and UVP latch off is reset when EN goes low level.
UVLO PROTECTION
TPS53114 has V5FILT under voltage lock out protection (UVLO) that monitors the voltage of V5FILT pin. When
the V5FILT voltage is lower than UVLO threshold voltage, the device is shut off. All output drivers are OFF and
output discharge is ON. The UVLO is non-latch protection.
THERMAL SHUTDOWN
The TPS53114 includes an over temperature protection shut-down feature. If the TPS53114 die temperature
exceeds the OTP threshold (typically 150°C), both the high-side and low-side drivers are shut off, the output
voltage discharge function is enabled and then the device is shut off until the die temperature drops. Thermal
shutdown is a non-latch protection.
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