Q24S25033-NBA0
| Model | Q24S25033-NBA0 |
| Description | DC-DC Regulated Power Supply Module, 1 Output, Hybrid, |
| PDF file | Total 14 pages (File size: 392K) |
| Chip Manufacturer | BEL |
Q24T25033
18-36 Vdc Input, 25 A, 3.3 Vdc Output
When using remote sense, the output voltage at the con-
verter 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 con-
verter’s actual output power remains at or below the maxi-
mum allowable output power.
Vin (+)
Data Sheet
Q
Family
Converter
TM
Vout (+)
SENSE (+)
R
T-INCR
(Top View)
Vin
ON/OFF
TRIM
SENSE (-)
Rload
Vin (-)
Vout (-)
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. Trim up to 10% is guar-
anteed only at Vin
≥
20 V, and it is marginal (8% to 10%) at
Vin = 18 V.
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.
To increase the output voltage, refer to Fig. 4. A trim resistor,
R
T-INCR
, should be connected between the TRIM (Pin 6) and
SENSE(+) (Pin 7), with a value of:
where,
Fig. 4:
Configuration for increasing output voltage.
R
T
−DECR
=
Required value of trim-down resistor [k
Ω
]
and
∆
is as defined above.
Note: The above equations for calculation of trim resistor
values match those typically used in conventional industry-
standard quarter bricks.
Vin (+)
Family
Converter
TM
Q
Vout (+)
SENSE (+)
TRIM
SENSE (-)
R
T-DECR
Rload
(Top View)
R
T
−
INCR
=
where,
5.11(100
+
∆)V
O
−
NOM
−
626
−
10.22
[k
Ω
]
1.225∆
Vin
ON/OFF
Vin (-)
Vout (-)
R
T
−INCR
=
Required value of trim-up resistor k
Ω
]
V
O
−NOM
=
Nominal value of output voltage [V]
Fig. 5:
Configuration for decreasing output voltage.
∆
=
(V
O-REQ
−
V
O-NOM
)
X 100
[%]
V
O -NOM
V
O
−REQ
=
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.
To decrease the output voltage (Fig. 5), a trim resistor,
R
T-DECR
, should be connected between the TRIM (Pin 6) and
SENSE(-) (Pin 5), with a value of:
R
T
−
DECR
=
511
−
10.22
[k
Ω
]
∆
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 0.33 V, or:
[V
OUT
(
+
)
−
V
OUT
(
−
)]
−
[V
SENSE
(
+
)
−
V
SENSE
(
−
)]
≤
0.33
[V]
This equation is applicable for any condition of output sens-
ing and/or output trim.
Q24T25033 FDS Ver 2 05-01-03
USA Toll Free 866 WOW-didt
Page 6 of 14
