Datasheet

Inductor
CSP
R
C
H-FET
L-FET
SW
Cout
V5SW
R1
R2
VFB
CSN
Vout
C
O
Lx
Rs(DCR)
+
Cx
Rx
CSP
CSN
Inductor
Rc1
Rc2
R
NTC
TPS51220A
www.ti.com SLUS897E –DECEMBER 2008–REVISED JANUARY 2013
Figure 50. Inductor DCR Current Sensing With Temperature Compensate
LAYOUT CONSIDERATIONS
Certain points must be considered before starting a PCB layout work using the TPS51220A.
Placement
• Place RC network for CSP1 and CSP2 close to the device pins.
• Place bypass capacitors for VREG5, VREG3 and VREF2 close to the device pins.
• Place frequency-setting resistor close to the device pin.
• Place the compensation circuits for COMP1 and COMP2 close to the device pins.
• Place the voltage setting resistors close to the device pins, especially when D-CAP mode is chosen.
Routing (sensitive analog portion)
• Use separate traces for; see Figure 51
– Output voltage sensing from current sensing (negative-side)
– Output voltage sensing from V5SW input (when V
OUT
= 5V)
– Current sensing (positive-side) from switch-node
Figure 51. Sensing Trace Routings
• Use Kelvin sensing traces from the solder pads of the current sensing device (inductor or resistor) to current
Copyright © 2008–2013, Texas Instruments Incorporated Submit Documentation Feedback 33
Product Folder Links :TPS51220A