Data Sheet
JNW350R Power Modules; DC-DC Converters
36 – 75 Vdc Input; 28Vdc Output; 350W Output
July 27, 2009
Feature Description (continued)
Figure 17. Circuit Configuration to Actively Adjust
the Output Voltage.
Figure 16. Circuit Configuration to Increase
Output Voltage, JNW350Rx-T option.
Tunable Loop™
Examples:
The JNW350Rx-T modules have a new feature that
optimizes transient response of the module called
Tunable Loop™.
To trim down the output of a nominal 28V JNW350-T
module to 16.8V
28V −16.8V
Δ% =
×100
External capacitors are usually added to the output of
the module for two reasons: to reduce output ripple
and noise and to reduce output voltage deviations
from the steady-state value in the presence of
dynamic load current changes. Adding external
capacitance however affects the voltage control loop
of the module, typically causing the loop to slow down
with sluggish response. Larger values of external
capacitance could also cause the module to become
unstable.
The Tunable LoopTM allows the user to externally
adjust the voltage control loop to match the filter
network connected to the output of the module. The
Tunable LoopTM is implemented by connecting a
series R-C between the SENSE(+) and TRIM pins of
the module, as shown in Fig. 48. This R-C allows the
user to externally adjust the voltage loop feedback
compensation of the module.
28V
∆% = 40
10631.45
⎛
⎜
⎞
⎠
R
adj − down
=
−111.2 kΩ
⎟
40
⎝
R
adj - down = 154.5 kΩ
To trim up the output of a nominal 28V JNW350-T
module to 30.8V
30.8V − 28V
Δ% =
×100
28V
Δ% = 10
20.47
10
⎛
⎜
⎞
⎟
R
adj − up
=
kΩ
⎝
⎠
Radj - up = 2.0 kꢀ
Active Voltage Programming
For both the JNW350Rx and JNW350Rx-T, a Digital-
Analog converter (DAC), capable of both sourcing
and sinking current, can be used to actively set the
output voltage, as shown in Figure 17. The value of
RG will be dependent on the voltage step and range of
the DAC and the desired values for trim-up and trim-
down Δ%. Please contact your Lineage Power
technical representative to obtain more details on the
selection for this resistor.
Figure 18. Circuit diagram showing connection of
RTUNE and CTUNE to tune the control loop of the
module.
Recommended values of RTUNE and CTUNE for different
output capacitor combinations are given in Tables 1
and 2. Table 1 shows the recommended values of
LINEAGE POWER
10
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