Datasheet

www.ti.com
APPLICATION INFORMATION
ADJUSTING THE OUTPUT VOLTAGE
V
I
V
O
GND
PTH12050
1
63
4
2
Track
V
I
V
O
GNDInhibit
Adjust
* Requiredwithoutputvoltages 3.3V>
5
C1
100 F
(Required)
m
C2*
10 F
Ceramic
m
R ,
1%
SET
C3
100 F
(Optional)
m
PTH12050W/L
SLTS214H – MAY 2003 – REVISED OCTOBER 2007
The V
O
Adjust control (pin 5) sets the output voltage of the PTH12050 product. The adjustment range is from
1.2 V to 5.5 V for the W-suffix modules and 0.8 V to 1.8 V for L-suffix modules. 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 Equation 1 , or simply selected from the range of values given in
Table 3 .Figure 10 shows the placement of the required resistor.
Table 1. Standard Values of R
SET
for Standard Output Voltages
PTH12050W PTH12050L
V
O
V
O
V
O
R
SET
(k Ω ) R
SET
(k Ω )
(Required) (V) (Actual) (V) (Actual) (V)
5 0.280 5.009 N/A N/A
3.3 2.0 3.294 N/A N/A
2.5 4.32 2.503 N/A N/A
2 8.06 2.010 N/A N/A
1.8 11.5 1.801 0.130 1.800
1.5 24.3 1.506 3.57 1.499
1.2 Open 1.200 12.1 1.201
1.1 N/A N/A 18.7 1.101
1.0 N/A N/A 32.4 0.999
0.9 N/A N/A 71.5 0.901
0.8 N/A N/A Open 0.800
(1) A 0.05-W rated resistor can be used. The tolerance should be 1%, with a temperature stability of 100 ppm/ ° C or
better. Place the resistor as close to the regulator as possible. Connect the resistor directly between pins 5 and 1
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 10. V
O
Adjust Resistor Placement
8 Submit Documentation Feedback Copyright © 2003 – 2007, Texas Instruments Incorporated
Product Folder Link(s): PTH12050W/L