GE Industrial Solutions Austin Lynx II 12 V SMT - Manual (Page 13)

Data Sheet
October 1, 2009 Austin Lynx TM II 12 V SMT Non-Isolated Power Modules:
8.3 – 14.0 Vdc Input; 0.75Vdc to 5.5Vdc Output; 10A output current
LINEAGE POWER 13
Feature Descriptions (continued)
Output Voltage Programming
The output voltage of the Austin Lynx TM II 12V can be
programmed to any voltage from 0.75Vdc to 5.5Vdc by
connecting a resistor (shown as Rtrim in Figure 29)
between Trim and GND pins of the module. Without an
external resistor between Trim and GND pins, the output
of the module will be 0.7525Vdc. To calculate the value
of the trim resistor, Rtrim for a desired output voltage, use
the following equation:
Ω
⎥⎦
⎤
⎢⎣
⎡
−
−
= 1000
7525 . 0
10500
Vo
Rtrim
For example, to program the output voltage of the Austin
Lynx
TM II 12 V module to 1.8 Vdc, Rtrim is calculated is
follows:
⎥⎦
⎤
⎢⎣
⎡
−
−
= 1000
75 . 0 8 . 1
10500
Rtrim
Ω = k Rtrim 024 . 9
V
O
(+)
TRIM
GND
LOAD
V
IN
(+)
ON/OFF
Rtrim
Figure 29. Circuit configuration for programming
output voltage using an external resistor.
Table 1 provides Rtrim values required for some common
output voltages
Table 1
V
O, set
(V) Rtrim (KΩ)
0.7525 Open
1.2 22.46
1.5 13.05
1.8 9.024
2.5 5.009
3.3 3.122
5.0 1.472
By using a 1% tolerance trim resistor, set point tolerance
of ±2% is achieved as specified in the electrical
specification. The POL Programming Tool, available at
www.lineagepower.com under the Design Tools section,
helps determine the required external trim resistor
needed for a specific output voltage.
The amount of power delivered by the module is defined
as the voltage at the output terminals multiplied by the
output current. When using the trim feature, the output
voltage of the module can be increased, which at the
same output current would increase the power output of
the module. Care should be taken to ensure that the
maximum output power of the module remains at or
below the maximum rated power (P
max
= V
o,set
x I
o,max
).
Voltage Margining
Output voltage margining can be implemented in the
Austin Lynx
TM II modules by connecting a resistor, R
margin-
up
, from the Trim pin to the ground pin for margining-up
the output voltage and by connecting a resistor, R
margin-
down
, from the Trim pin to the Output pin for margining-
down. Figure 30 shows the circuit configuration for
output voltage margining. The POL Programming Tool,
available at
www.lineagepower.com under the Design
Tools section, also calculates the values of R
margin-up
and
R
margin-down
for a specific output voltage and % margin.
Please consult your local Lineage Power technical
representative for additional details.
Vo
Austin Lynx or
Lynx II Series
GND
Trim
Q1
Rtrim
Rmargin-up
Q2
Rmargin-down
Figure 30. Circuit Configuration for margining Output
voltage.