Q24T25015 DC-DC Converter Data Sheet
18-36 VDC Input; 1.5 VDC @ 25A Output
When using remote sense, the output voltage at the conver-
ter 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 al-
lowable output power.
TM
Family
Q
Vin (+)
ON/OFF
Vin (-)
Vout (+)
SENSE (+)
TRIM
Converter
(Top View)
R T-INCR
Rload
Vin
SENSE (-)
Vout (-)
Fig. 4: Configuration for increasing output voltage.
Output Voltage Adjust /TRIM (Pin 6)
The converter’s output voltage can be adjusted up 10% or
down 20% relative to the rated output voltage by the addition
of an externally connected resistor.
RTDECR Required value of trim-down resistor [k]
and Δ is as defined above.
The TRIM pin should be left open if trimming is not being
used. To minimize noise pickup, a 0.1 µF capacitor is con-
nected internally between the TRIM and SENSE(-) pins.
Note: The above equations for calculation of trim resistor
values match those typically used in conventional industry-
standard quarter bricks.
To increase the output voltage, refer to Fig. 4. A trim resistor,
R
T-INCR, should be connected between the TRIM (Pin 6) and
TM
SENSE(+) (Pin 7), with a value of:
Family
Q
Vin (+)
ON/OFF
Vin (-)
Vout (+)
SENSE (+)
TRIM
Converter
(Top View)
Rload
5.11(100 Δ)VONOM 626
Vin
RT-DECR
R
TINCR
10.22 [k]
SENSE (-)
Vout (-)
1.225Δ
where,
RTINCR Required value of trim-up resistor k]
VONOM Nominal value of output voltage [V]
Fig. 5: Configuration for decreasing output voltage.
(VO-REQ VO-NOM)
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 over-voltage protec-
tion (OVP) circuit. The designer should ensure that the dif-
ference between the voltages across the converter’s output
pins and its sense pins does not exceed 0.15 V, or:
Δ
X 100 [%]
VO -NOM
VOREQ Desired (trimmed) output voltage [V].
When trimming up, care must be taken not to exceed the
converter‘s maximum allowable output power. See previous
section for a complete discussion of this requirement.
[VOUT() VOUT()][VSENSE() VSENSE()] 0.15 [V]
This equation is applicable for any condition of output sens-
ing and/or output trim.
To decrease the output voltage (Fig. 5), a trim resistor,
RT-DECR, should be connected between the TRIM (Pin 6) and
SENSE(-) (Pin 5), with a value of:
511
RTDECR
10.22 [k]
Δ
where,
MCD10220 Rev. 1.0, 26-Aug-10
Page 6 of 14
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