Datasheet

www.ti.com POWER-UP PROCEDURE
4.2 Jumpers and Switches
Table 2. Power Connectors
NO. FUNCTION DESCRIPTION
JP1 V
IN
Connector Apply power supply to this connector
JP3 SW_OUT Connector Output of power switch
JP4 SW_IN Connector Input of power switch
JP5 V
OUT_BUCK
Connector Output of buck converter
Table 3. Jumpers and Switches
NO. FUNCTION PLACEMENT COMMENT
Connect a external cap to this pin to program the soft start time
JP2 Soft Start (SS) of the buck converter; leave this pin open to have default 1-ms
soft start time.
Connect a resistor to this pin to set the switching frequency;
JP3, 4 Switching Frequency leave it open to set F
SW
to 600 kHz; connect it to ground to set
F
SW
to 300 kHz.
Connect this pin to high enable power switch 2; connect it to
JP5 Power Switch Enable ground to disable power switch 2; Leave it open to enable Not recommend to leave open
power switch through internal 1.25-MΩ pull up resistor.
Connect EN1 to GND to disable V
OUT1
, connect EN1 to V
IN
JP7 Buck Enable (EN) through a 100-kΩ resistor to enable V
OUT_BUCK
; Leave open to Not recommend to leave open
enable V
OUT_BUCK
.
JP8 Short Connector Short these pins to connect V
OUT_BUCK
to SW_IN.
Power switch current limit control pin. An external resistor used
to set current limit threshold of power switch. Recommended
JP9 Current Limit
15 kΩ ≤ R
LIM
≤ 232 kΩ. Leave this pin open or connect to
SW_IN to set current limit 1.2 A.
5 POWER-UP PROCEDURE
1. Apply 12 V to J1.
2. Toggle JP7 to enable V
OUT1
.
3. Toggle JP5 to enable power switch.
4. Apply load to the connectors, J3 or J5.
7
SLVU770–August 2012 TPS65281EVM User’s Guide
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