The QME48T40 DC-DC Series of converters provide outstanding thermal
performance in high temperature environments. This performance is
accomplished through the use of patented/patent-pending circuits,
packaging, and processing techniques to achieve ultra-high efficiency,
excellent thermal management, and a low-body profile.
The low-body profile and the preclusion of heat sinks minimize impedance to
system airflow, thus enhancing cooling for both upstream and downstream
devices. The use of 100% automation for assembly, coupled with advanced
electronic circuits and thermal design, results in a product with extremely high
reliability.
Operating from a 36-75 V input, the QME48T40 converters provide any
standard output voltage from 3.3 V down to 1.0 V that can be trimmed from –
20% to +10% of the nominal output voltage (±10% for output voltages 1.2 V
and 1.0 V), thus providing outstanding design flexibility.
RoHS lead-free solder and lead-solder-exempted products are
available
Delivers up to 40 A
Outputs available: 3.3, 2.5, 1.8, 1.5, 1.2 and 1.0 V
Industry-standard quarter-brick pinout
On-board input differential LC-filter
Startup into pre-biased load
No minimum load required
Dimensions: 1.45” x 2.30” x 0.425”
(36.83 x 58.42 x 10.80 mm)
Weight: 1.2 oz [34.2 g]
Meets Basic Insulation requirements of EN60950
Withstands 100 V input transient for 100 ms
Fixed-frequency operation
Fully protected
Remote output sense
Non-Latching / Latching OTP option
Positive or negative logic ON/OFF option
Output voltage trim range: +10%/−20% with industry-standard trim
equations (±10% for 1.2 V and 1.0 V)
High reliability: MTBF = 13.9 million hours, calculated per Telcordia TR-
332, Method I Case 1
Approved to the following Safety Standards: UL/CSA60950-1,
EN60950-1, and IEC60950-1
Designed to meet Class B conducted emissions per FCC and EN55022
when used with external filter
All materials meet UL94, V-0 flammability rating
Asia-Pacific
+86 755 298 85888
Europe, Middle East
+353 61 225 977
North America
+1 866 513 2839
© 2016 Bel Power Solutions, Inc.
BCD.00817_AA
`2
1.
Conditions: T
A
= 25ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, All output voltages, unless otherwise specified.
PARAMETER
Absolute Maximum Ratings
Input Voltage
Operating Ambient Temperature
Storage Temperature
Continuous
0
-40
-55
80
85
125
VDC
°C
°C
CONDITIONS / DESCRIPTION
MIN
TYP
MAX
UNITS
Input Characteristics
Operating Input Voltage Range
Input Under Voltage Lockout
Turn-on Threshold
Turn-off Threshold
Input Voltage Transient
100 ms
33
31
34
32
35
33
100
VDC
VDC
VDC
36
48
75
VDC
Isolation Characteristics
I/O Isolation
Isolation Capacitance
Isolation Resistance
10
2000
2
VDC
nF
MΩ
Feature Characteristics
Switching Frequency
Output Voltage Trim Range
1
Non-latching (3.3 - 1.5 V)
Non-latching (1.2 V and 1.0 V)
Remote Sense Compensation
1
Output Overvoltage Protection
Auto-Restart Period
Turn-On Time
ON/OFF Control (Positive Logic)
Converter Off (logic low)
Converter On (logic high)
ON/OFF Control (Negative Logic)
Converter Off (logic high)
Converter On (logic low)
1)
460
-20
-10
+10
+10
+10
117
128
200
4
140
kHz
%
%
%
%
ms
ms
Percent of VOUT(nom)
Non-latching
Applies to all protection features
-20
2.4
0.8
20
VDC
VDC
2.4
-20
20
0.8
VDC
VDC
Vout can be increased up to 10% via the sense leads or 10% via the trim function. However, the total output voltage trim from
all sources should not exceed 10% of VOUT(nom), in order to ensure specified operation of overvoltage protection circuitry
tech.support@psbel.com
3
2.
2.1
These power converters have been designed to be stable with no external capacitors when used in low inductance input
and output circuits.
In many applications, the inductance associated with the distribution from the power source to the input of the converter
can affect the stability of the converter. The addition of a 33 µF electrolytic capacitor with an ESR < 1
Ω
across the input
helps to ensure stability of the converter. In many applications, the user has to use decoupling capacitance at the load. The
power converter will exhibit stable operation with external load capacitance up to 40,000 µF on 3.3 V – 1.0 V outputs.
Additionally, see the EMC section of this data sheet for discussion of other external components which may be required for
control of conducted emissions.
2.2
The ON/OFF pin is used to turn the power converter on or off remotely via a system signal. There are two remote control
options available, positive and negative logic, with both referenced to Vin(-). A typical connection is shown in Fig. 1.
Vin (+)
QME Series
Converter
(Top View)
Vout (+)
SENSE (+)
TRIM
SENSE (-)
Rload
Vin
ON/OFF
Vin (-)
CONTROL
INPUT
Vout (-)
Figure 1. Circuit configuration for ON/OFF function.
The positive logic version turns on when the ON/OFF pin is at a logic high and turns off when at a logic low. The converter
is on when the ON/OFF pin is left open. See the Electrical Specifications for logic high/low definitions.
The negative logic version turns on when the pin is at a logic low and turns off when the pin is at a logic high. The ON/OFF
pin can be hardwired directly to Vin(-) to enable automatic power up of the converter without the need of an external control
signal.
The ON/OFF pin is internally pulled up to 5 V through a resistor. A properly debounced mechanical switch, open-collector
transistor, or FET can be used to drive the input of the ON/OFF pin. The device must be capable of sinking up to 0.2 mA at
a low level voltage of
0.8 V. An external voltage source (±20 V maximum) may be connected directly to the ON/OFF input,
in which case it must be capable of sourcing or sinking up to 1 mA depending on the signal polarity. See the Startup
Information section for system timing waveforms associated with use of the ON/OFF pin.
2.3
The remote sense feature of the converter compensates for voltage drops occurring between the output pins of the converter
and the load. The SENSE(-) (Pin 5) and SENSE(+) (Pin 7) pins should be connected at the load or at the point where regulation
is required (see Fig. 2).
QME Series
Vin (+)
Converter
(Top View)
Vin
ON/OFF
Vout (+)
100
Rw
SENSE (+)
TRIM
SENSE (-)
10
Rload
Vin (-)
Vout (+)
Rw
Figure 2. Remote sense circuit configuration
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CAUTION
If remote sensing is not utilized, the SENSE(-) pin must be connected to the Vout(-) pin (Pin 4), and the SENSE(+) pin must
be connected to the Vout(+) pin (Pin 8) to ensure the converter will regulate at the specified output voltage. If these
connections are not made, the converter will deliver an output voltage that is slightly higher than the specified data sheet
value.
Because the sense leads carry minimal current, large traces on the end-user board are not required. However, sense traces
should be run side by side and located close to a ground plane to minimize system noise and ensure optimum performance.
The converter’s output overvoltage protection (OVP) senses the voltage across Vout(+) and Vout(-), and not across the sense
lines, so the resistance (and resulting voltage drop) between the output pins of the converter and the load should be
minimized to prevent unwanted triggering of the OVP.
When utilizing the remote sense feature, care must be taken not to exceed the maximum allowable output power capability
of the converter, which is equal to the product of the nominal output voltage and the allowable output current for the given
conditions.
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.
2.4
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.
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(-) pins.
To increase the output voltage, refer to Fig. 3. A trim resistor, R
T-INCR
, should be connected between the TRIM (Pin 6) and
SENSE(+) (Pin 7), with a value of:
R
T
INCR
½
5.11(100
Δ)V
O
NOM
626
10.22
1.225Δ
[kΩ] (3.3-1.5V)
R
T
INCR
½
84.6
7.2
Δ
120
9
Δ
[kΩ] (1.2V)
R
T
INCR
½
where,
R
T-INCR
= Required value of trim-up resistor k]
V
O-NOM
= Nominal value of output voltage [V]
[kΩ] (1.0V)
Δ
½
(V
O -REQ
V
O -NOM
)
X 100
[%]
V
O -NOM
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.
tech.support@psbel.com
5
Vin (+)
QME Series
Converter
(Top View)
Vout (+)
SENSE (+)
R
T-INCR
Vin
ON/OFF
TRIM
SENSE (-)
Rload
Vin (-)
Vout (-)
Figure 3. Configuration for increasing output voltage.
To decrease the output voltage (Fig. 4), 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
½
511
10.22
|Δ|
[kΩ] (3.3 - 1.5V)
R
T
DECR
½
R
T
DECR
½
where,
R
T-DECR
Required value of trim-down resistor [k]
and
700
15
[kΩ] (1.2V)
|Δ|
700
17
[kΩ] (1.0V)
|Δ|
Δ
is as defined above.
Note:
The above equations for calculation of trim resistor values match those typically used in conventional industry-standard
quarter-bricks (except for 1.2 V and 1.0 V outputs).
Vin (+)
QME Series
Converter
(Top View)
Vout (+)
SENSE (+)
TRIM
R
T-DECR
Rload
Vin
ON/OFF
SENSE (-)
Vin (-)
Vout (-)
Figure 4. 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 10% of VOUT(nom), or:
[V
OUT
() V
OUT
()] [V
SENSE
() V
SENSE
()] V
O - NOM X
10%
This equation is applicable for any condition of output sensing and/or output trim.
[V]
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