Datasheet

TPS51219
10
6
DL
TRIP
UDG-11043
R
EXT
Cx
ESL
Rx
+
+
25 mV
(typ)
Lx
I
OUT
TPS51219
10
6
DL
TRIP
UDG-11044
R
EXT
Cx
ESL
R
X
+
+
25 mV
(typ)
Lx
I
OUT
R
XC
( )
´ =
X X XC
EXT
ESL
C R R
R
æ ö æ ö
+ -
= + + ´
ç ÷ ç ÷
´ ´
è ø è ø
X XC IN OUT OUT
OCL
EXT XC X SW IN
R R V V V
25mV
I
R R 2 L f V
( )
( )
æ ö
+
= ´
ç ÷
ç ÷
æ ö
-
è ø
- ´
ç ÷
ç ÷
´ ´
è ø
X XC
EXT
XC
IN OUT
OUT
OCL
X SW IN
R R
25mV
R
R
V V
V
I
2 L f V
= £
p´ ´
SW
0
OUT
f
1
f
2 ESR C 3
£
p´
f
0
M
g
2 C1 10
´
³
´
OUT
SW
V ESR
20mV
f Lx
TPS51219
SLUSAG1B – MARCH 2011– REVISED OCTOBER 2011 www.ti.com
Figure 28. Resistor Sensing with Compensation Figure 29. Adjustment of Overcurrent Limitation in
Resistor Sensing
A voltage divider can be configured to adjust for overcurrent limitation, as described in Figure 29. For R
X
, R
XC
and C
X
can be calculated as shown in Equation 16, and the overcurrent limitation value can be calculated as
shown in Equation 17.
(16)
(17)
Therefore, R
EXT
can be obtained using Equation 18.
(18)
4. CHOOSE THE OUTPUT CAPACITORS
D-CAP™ Mode
Organic semiconductor capacitor(s) or specialty polymer capacitor(s) are recommended. Determine the ESR
value to meet small signal stability and recommended ripple voltage. A quick reference is shown in Equation 19
and Equation 20.
(19)
where
• g
M
is 130 µS (typ)
• C1 is the capacitance connected between the VSNS and COMP pins (20)
(21)
22 Submit Documentation Feedback Copyright © 2011, Texas Instruments Incorporated