QM48 Series - 45A
Data Sheet
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.
QmaXTM Series
Converter
Vin (+)
ON/OFF
Vin (-)
Vout (+)
SENSE (+)
TRIM
(Top View)
R T-INCR
Rload
Vin
SENSE (-)
Vout (-)
Fig. C: Configuration for increasing output voltage.
Output Voltage Adjust /TRIM (Pin 6)
To decrease the output voltage (Fig. D), a trim resistor,
RT-DECR, should be connected between the TRIM (Pin 6) and
SENSE(-) (Pin 5), with a value of:
The output voltage can be adjusted up 10% or down 20% for
Vout ≥ 1.5 V, and ±10% for Vout = 1.2 V and 1.0 V relative
to the rated output voltage by the addition of an externally
connected resistor. For 3.3 V output voltage, trim up to 10%
is guaranteed only at Vin ≥ 40 V, and it is marginal (8% to
10%) at Vin = 36 V.
511
RT−DECR
RT−DECR
RT−DECR
=
=
=
−10.22 [kΩ] (3.3 - 1.5 V)
− 15 [kΩ] (1.2 V)
| ∆ |
700
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.
| ∆ |
700
− 17 [kΩ] (1.0 V)
To increase the output voltage, refer to Fig. C. A trim resis-
tor, RT-INCR, should be connected between the TRIM (Pin 6)
and SENSE(+) (Pin 7), with a value of:
| ∆ |
where,
RT−DECR = Required value of trim-down resistor [kΩ]
and ∆ is as defined above.
5.11(100 + ∆)VO−NOM − 626
R
R
R
T−INCR
=
=
=
− 10.22 [kΩ] (3.3 -1.5V)
1.225∆
Note: The above equations for calculation of trim resistor
values match those typically used in conventional industry-
standard quarter bricks (except for 1.2V and 1.0 V outputs).
84.6
T−INCR
T−INCR
− 7.2 [kΩ] (1.2 V)
∆
Converters with output voltages 1.2 V and 1.0 V are avail-
able with alternative trim feature to provide the customers
with the flexibility of second sourcing. For these converters,
the last character in the part number is “T”. The trim equa-
tions of “T” version of converters and more information can
be found in Application Note 103.
120
− 9 [kΩ] (1.0 V)
∆
where,
RT−INCR = Required value of trim-up resistor kΩ]
VO−NOM = Nominal value of output voltage [V]
TM Series
Converter
QmaX
Vin (+)
ON/OFF
Vin (-)
Vout (+)
SENSE (+)
TRIM
(VO-REQ − VO-NOM)
∆ =
X 100 [%]
(Top View)
VO -NOM
Rload
Vin
RT-DECR
SENSE (-)
Vout (-)
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 previous
section for a complete discussion of this requirement.
Fig. D: Configuration for decreasing output voltage.
QM48T45 Family DS Ver 3 03-27-03
USA Toll Free 866 WOW-didt
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