Datasheet

R
set
+ 10 kW
0.8 V
V
out
* 0.8 V
* 2.49 kW
R
SET
1%
0.05
W
PTH04040W
12
15
9
10 13 16
11
14
18
V
O
V
O
C
O
+Sense
−Sense
GND
Track
Adjust
17
GNDGND
PTH04040W
www.ti.com SLTS238C –SEPTEMBER 2005–REVISED JUNE 2010
ADJUSTING THE OUTPUT VOLTAGE OF THE PTH04040W
The V
O
Adjust control (pin 17) sets the output voltage of the PTH04040W to a value higher than 0.8 V. The
adjustment range is from 0.8 V to 2.5 V. For an output voltage other than 0.8 V a single external resistor, R
SET
1,
must be connected directly between the V
O
Adjust (pin 17) and the output GND (pin 16)
(2)
. Table 2 gives the
preferred 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 is calculated using the following formula, or by
selecting from the range of values given in Table 3. Figure 9 shows the placement of the required resistor.
(1)
Table 2. Preferred Values of R
set
for Standard Output Voltages
V
OUT
(Standard)
(1)
R
SET
(Preferred Value) V
OUT
(Actual)
2.5 V 2.21 kΩ 2.502 V
2 V 4.12 kΩ 2.010 V
1.8 V 5.49 kΩ 1.803 V
1.5 V 8.87 kΩ 1.504 V
1.2 V 17.4 kΩ 1.202 V
1 V 36.5 kΩ 1.005 V
0.8 V Open 0.8 V
(1) The nominal input voltage must be at least 2 × V
O
. Output voltage regulation is specified with an input voltage within ±10% from nominal
3.3 V or 5 V. For example, for V
I
= 5 V and V
O
= 2.5 V, the input can vary between 4.5 V and 5.5 V.
Figure 9. V
O
Adjust Resistor Placement
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