Datasheet
APPLICATION INFORMATION
ADJUSTING THE OUTPUT VOLTAGE
R
set
+ 10 kW
0.8 V
V
out
* 0.8 V
*2.49 kW
(1)
V
IN
C
IN
100 µF
(Required)
+
C
OUT
100 µF
(Optional)
+
GND
V
OUT
R
SET
1 %
0.1 W
PTH05050W
1
63
4
2
Track
V
IN
V
O
GNDInhibit
5
PTH05050W
SLTS213E – MAY 2003 – REVISED MARCH 2009 ............................................................................................................................................................
www.ti.com
The V
o
Adjust control (pin 5) sets the output voltage to value higher than 0.8 V. The adjustment range of the
PTH05050W is from 0.8 V to 3.6 V. 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 5 shows the placement of the required
resistor.
Table 1. Values of R
SET
for Standard Output Voltages
V
O
(Standard) (V) R
SET
(Standard Value) (k Ω ) V
O
(Actual) (V)
3.3 0.698 3.309
2.5 2.21 2.502
2 4.12 2.010
1.8 5.49 1.803
1.5 8.87 1.504
1.2 17.4 1.202
1 36.5 1.005
0.8 Open 0.8
Figure 5. V
O
Adjust Resistor Placement
NOTES:
1. A 0.05-W resistor may be used. 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 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 will
affect the stability of the regulator.
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