Datasheet

PTV12020
10, 11
7
3, 4
+
GND
GND
1, 2
GND
V
O
Sense
V
O
V
O
Adj
V
O
Sense
V
O
C
O
330 mF
(Optional)
8
R
SET
1%, 0.05W
PTV12020W/L
SLTS231C –NOVEMBER 2004–REVISED FEBRUARY 2007 www.ti.com
APPLICATION INFORMATION
ADJUSTING THE OUTPUT VOLTAGE
The V
O
Adjust control (pin 8) sets the output voltage of the PTV12020 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
(pin 1 or 2). 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 11 shows the placement of the required resistor.
Table 1. Standard Values of R
SET
for Common Output Voltages
PTV12020W PTV12020L
V
O
(V) R
SET
(kΩ) V
O
(V) R
SET
(kΩ) V
O
(V)
(Required) (Standard Value) (Actual) (Standard Value) (Actual)
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 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 pin 8 and pins 1
or 2, 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 11. V
O
Adjust Resistor Placement
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