FEATURE DESCRIPTIONS (CON.
)
Table 1 provides Rtrim values required for some common
output voltages, while Table 2 provides value of external
voltage source, Vtrim, for the same common output
voltages. By using a 1% tolerance trim resistor, set point
tolerance of ±2% can be achieved as specified in the
electrical specification.
Table 1
VO (V)
0.7525
1.2
1.5
1.8
2.5
3.3
5.0
Rtrim (KΩ)
Open
22.464
13.047
9.024
5.009
3.122
1.472
The amount of power delivered by the module is 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 must not exceed
the maximum rated power (
Vo.set x Io.max
≤
P max
).
Voltage Margining
Output voltage margining can be implemented in the
DNS 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 25
shows the circuit configuration for output voltage
margining. If unused, leave the trim pin unconnected. A
calculation tool is available from the evaluation
procedure, which computes the values of R
margin-up
and
R
margin-down
for a specific output voltage and margin
percentage.
Table 2
VO (V)
0.7525
1.2
1.5
1.8
2.5
3.3
5.0
Vtrim (V)
Open
0.670
0.650
0.630
0.583
0.530
0.4167
Vin
Vo
Rmargin-down
Q1
On/Off
Trim
Rmargin-up
Rtrim
GND
Q2
Figure 25:
Circuit configuration for output voltage margining
Voltage Tracking
The DNS family was designed for applications that have
output voltage tracking requirements during power-up
and power-down. The devices have a TRACK pin to
implement three types of tracking method: sequential
start-up, simultaneous and ratio-metric. TRACK simplifies
the task of supply voltage tracking in a power system by
enabling modules to track each other, or any external
voltage, during power-up and power-down.
By connecting multiple modules together, customers can
get multiple modules to track their output voltages to the
voltage applied on the TRACK pin.
DS_DNS10SIP06_03092009
9
DELTA [ DELTA ELECTRONICS, INC. ]
