Datasheet

APPLICATION INFORMATION
ADJUSTING THE OUTPUT VOLTAGE
R
SET
+ 30.1 kW
0.7
V
O
* 0.7
* 6.49 kW
(1)
5
9
3 4 7 8
10
11
GND GND
12
GND
+Sense
+Sense
V
O
V
O
−Sense
V
O
Adj
−Sense
R
SET
1%
0.05 W
C
O
PTH05T210W
PTH05T210W
SLTS263I – AUGUST 2007 – REVISED MARCH 2009 ...................................................................................................................................................... www.ti.com
The V
O
Adjust control (pin 12) sets the output voltage of the PTH05T210W. The adjustment range of the
PTH05T210W is 0.7V to 3.6V. The adjustment method requires the addition of a single external resistor, R
SET
,
that must be connected directly between the V
o
Adjust and GND pins. Table 1 gives the standard value of the
external resistor for a number of standard voltages, along with the actual output voltage that this resistance value
provides.
For other output voltages, the value of the required resistor can either be calculated using the following formula,
or simply selected from the range of values given in Table 2 . Figure 6 shows the placement of the required
resistor.
Table 1. Standard Values of R
SET
for Standard Output Voltages
V
O
(Standard) (V) R
SET
(Standard Value) ( Ω ) V
O
(Actual) (V)
3.3 1.62 k 3.298
2.5 5.23 k 2.498
2 9.76 k 1.997
1.8 12.7 k 1.798
1.5 19.6 k 1.508
1.2 35.7 k 1.199
1 63.4 k 1.001
0.7 Open 0.700
(1) Use a 0.05 W resistor. The tolerance should be 1%, with temperature stability of 100 ppm/ ° C (or better). Place the
resistor as close to the regulator as possible. Connect the resistor directly between pins 12 and 8 using dedicated
PCB traces.
(2) Never connect capacitors from V
O
Adjust to either GND or V
O
. Any capacitance added to the V
O
Adjust pin affects the
stability of the regulator.
Figure 6. V
O
Adjust Resistor Placement
8 Submit Documentation Feedback Copyright © 2007 – 2009, Texas Instruments Incorporated
Product Folder Link(s): PTH05T210W