Datasheet

www.ti.com
APPLICATION INFORMATION
Adjusting the Output Voltage of the PTN04050A Wide-Output Adjust Power Modules
General
R =-4.34k x
SET
W
V +1.734V
O
V +16.6V
O
(1)
GND
V
O
V
I
R
0.05W,1%
SET
PTN04050A
4
52
Adj
GND
V
O
V
I
GND
Inhibit
1
3
+
+
C1
C
O
PTN04050A
SLTS250 – SEPTEMBER 2005
A resistor must be connected directly between the V
O
Adjust control (pin 4) and GND (pin 1) to set the output
voltage of the module. The adjustment range is from –15 V to –3.3 V. If pin 4 is left open, the output voltage
defaults to –1.79 V, which is beyond the recommended operating range.
Table 1 gives the standard resistor value for a number of common voltages, along with the actual output voltage
that the value produces. For other output voltages, the resistor value can either be calculated using Equation 1 ,
or by selecting from the range of values given in Table 2 . Figure 15 shows the placement of the required
resistor.
Table 1. Standard Values of R
set
for Common Output
Voltages
V
O
R
SET
V
O
(Required) (Standard Value) (Actual)
–15 V
(1)
523 Ω –15.00 V
–12 V
(2)
1.91 k Ω –12.02 V
–5 V
(2)
15.4 k Ω –5.00 V
–3.3 V
(2)
36.5 k Ω –3.31 V
(1) For V
O
= –12.6 V to –15 V the maximum output current is limited to
0.3 A.
(2) For V
O
= –3.3 V to – 12.6 V the maximum output current is 1 A or
the maximum output power is 6 W, whichever is less.
(1) A 0.05-W rated resistor may be used. The tolerance should be 1%, with a temperature stability of 100 ppm/°C (or
better). Place the resistor as close as possible to the regulator. Connect the resistor directly between pins 4 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 15. V
O
Adjust Resistor Placement
7
Submit Documentation Feedback