HBC48T25120 Datasheet, PDF (5/16 Pages) Power-One – HBC48T25120 DC-DC Converter Data Sheet

HBC48T25120 DC-DC Converter Data Sheet
36-75 VDC Input; 12 VDC @ 25 A Output
When using remote sense, the output voltage at the
converter can be increased by as much as 10%
above the nominal rating in order to maintain the
required voltage across the load. Therefore, the
designer must, if necessary, decrease the maximum
current (originally obtained from the derating curves)
by the same percentage to ensure the converter’s
actual output power remains at or below the
maximum allowable output power.
Output Voltage Adjust /TRIM (Pin 7)
The output voltage can be adjusted up 10% or down
20% relative to the rated output voltage by the
addition of an externally connected resistor. (Trim up
to 10% at full load is guaranteed at Vin ≥ 40V.)
The TRIM pin should be left open if trimming is not
being used. To minimize noise pickup, a 0.1 µF
capacitor is connected internally between the TRIM
and SENSE(-) pin.
To increase the output voltage, refer to Fig. C. A trim
resistor, R_T-INCR, should be connected between the
TRIM (Pin 7) and SENSE(+) (Pin 8), with a value of:
R TINCR

VONOM (100  Δ)
1.225Δ

(100  2Δ)
Δ
[kΩ]
where,
RTINCR  Required value of trim-up resistor [kΩ]
VONOM  Nominal value of output voltage [V]
Δ
(VO-REQ  VO-NOM)
VO -NOM
X 100
[%]
VOREQ  Desired (trimmed) output voltage [V].
When trimming up, care must be taken not to exceed
the converter‘s maximum allowable output power.
See the previous section for a complete discussion
of this requirement.
VIN (+)
VOUT (+)
ON/OFF
SENSE (+)
VIN
(Top View)
TRIM
RT-INCR
Rload
CASE
SENSE (-)
VIN (-)
VOUT (-)
Fig. C: Configuration for increasing output voltage.
To decrease the output voltage (Fig. D), a trim
resistor, R_T-DECR, should be connected between the
TRIM (Pin 7) and SENSE(-) (Pin 6), with a value of:
RTDECR

100
|Δ|

2
[kΩ]
where,
RTDECR  Required value of trim-down resistor [kΩ]
and Δ is defined above.
Note:
The above equations for calculation of trim resistor values match
those typically used in conventional industry-standard half-bricks.
VIN (+)
VOUT (+)
ON/OFF
SENSE (+)
VIN
(Top View)
TRIM
RT-DECR
Rload
CASE
SENSE (-)
VIN (-)
VOUT (-)
Fig. D: Configuration for decreasing output voltage.
Trimming/sensing beyond 110% of the rated output
voltage is not an acceptable design practice, as this
condition could cause unwanted triggering of the
output overvoltage protection (OVP) circuit. The
designer should ensure that the difference between
the voltages across the converter’s output pins and
its sense pins does not exceed 110% of V_OUT(NOM),
or:
[VOUT()  VOUT()] [VSENSE()  VSENSE()]  VO - NOMX10% [V]
This equation is applicable for any condition of
output sensing and/or output trim.
MCD10127 Rev. 1.1, 09-Jun-10
Page 5 of 16
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