Datasheet

TPS65251
www.ti.com SLVSAA4D –JUNE 2010–REVISED DECEMBER 2012
TERMINAL FUNCTIONS (DCA)
NAME NO. I/O DESCRIPTION
RLIM3 1 I Current limit setting for Buck 3. Fit a resistor from this pin to ground to set
the peak current limit on the output inductor.
SS3 2 I Soft start pin for Buck 3. Fit a small ceramic capacitor to this pin to set the
converter soft start time.
COMP3 3 O Compensation for Buck 3. Fit a series RC circuit to this pin to complete
the compensation circuit of this converter.
FB3 4 I Feedback input for Buck 3. Connect a divider set to 0.8V from the output
of the converter to ground.
SYNC 5 I Synchronous clock input. If there is a sync clock in the system, connect to
the pin. When not used connect to GND.
ROSC 6 I Oscillator set. This resistor sets the frequency of internal autonomous
clock. If external synchronization is used resistor should be fitted and set
to ~70% of external clock frequency.
FB1 7 I Feedback pin for Buck 1. Connect a divider set to 0.8 V from the output of
the converter to ground.
COMP1 8 O Compensation pin for Buck 1. Fit a series RC circuit to this pin to
complete the compensation circuit of this converter.
SS1 9 I Soft start pin for Buck 1. Fit a small ceramic capacitor to this pin to set the
converter soft start time.
RLIM1 10 I Current limit setting pin for Buck 1. Fit a resistor from this pin to ground to
set the peak current limit on the output inductor.
EN1 11 I Enable pin for Buck 1. A low level signal on this pin disables it. If pin is
left open a weak internal pull-up to V3V will allow for automatic enable.
For a delayed start-up add a small ceramic capacitor from this pin to
ground.
BST1 12 I Bootstrap capacitor for Buck 1. Fit a 47-nF ceramic capacitor from this pin
to the switching node.
VIN1 13 I Input supply for Buck 1. Fit a 10-µF ceramic capacitor close to this pin.
LX1 14, 15 O Switching node for Buck 1
LX2 16, 17 O Switching node for Buck 2
VIN2 18 I Input supply for Buck 2. Fit a 10-µF ceramic capacitor close to this pin.
BST2 19 I Bootstrap capacitor for Buck 2. Fit a 47-nF ceramic capacitor from this pin
to the switching node.
EN2 20 I Enable pin for Buck 2. A low level signal on this pin disables it. If pin is
left open a weak internal pull-up to V3V will allow for automatic enable.
For a delayed start-up add a small ceramic capacitor from this pin to
ground.
RLIM2 21 I Current limit setting for Buck 2. Fit a resistor from this pin to ground to set
the peak current limit on the output inductor.
SS2 22 I Soft start pin for Buck 2. Fit a small ceramic capacitor to this pin to set the
converter soft start time.
COMP2 23 O Compensation pin for Buck 2. Fit a series RC circuit to this pin to
complete the compensation circuit of this converter
FB2 24 I Feedback input for Buck 2. Connect a divider set to 0.8 V from the output
of the converter to ground.
LOW_P 25 I Low power operation mode(active high) input for TPS65251
GND 26 Ground pin
PGOOD 27 O Power good. Open drain output asserted after all converters are
sequenced and within regulation. Polarity is factory selectable (active high
default).
V7V 28 O Internal supply. Connect a 10-μF ceramic capacitor from this pin to
ground.
V3V 29 O Internal supply. Connect a 3.3-μF to 10-μF ceramic capacitor from this pin
to ground.
AGND 30 Analog ground. Connect all GND pins and the power pad together.
GND 31 Ground pin
Copyright © 2010–2012, Texas Instruments Incorporated Submit Documentation Feedback 5
Product Folder Links: TPS65251