QM48T45 Family DC-DC Converter Data Sheet
36-75 VDC Input; 1.0-3.3 VDC @ 45 A Output
Features
•
RoHS lead-free solder and lead-solder-exempted
products are available
•
Delivers up to 45 A (150 W)
•
Industry-standard quarter-brick pinout
•
On-board input differential LC-filter
•
Outputs available: 3.3, 2.5, 2.0, 1.8, 1.5, 1.2 & 1.0 V
•
Start-up into pre-biased load
•
No minimum load required
•
Low profile: 0.31” [7.9 mm]
•
Low weight: 1.1 oz [31.5 g]
•
Meets Basic Insulation requirements of EN60950
•
Withstands 100 V input transient for 100 ms
•
Fixed-frequency operation
•
Remote output sense
•
Fully protected with automatic recovery
•
Positive or negative logic ON/OFF option
•
Output voltage trim range: +10%/−20% with
industry-standard trim equations (except 1.2 V and
1.0 V outputs with trim range
±10%)
•
High reliability: MTBF = 2.6 million hours, calculated
per Telcordia TR-332, Method
I
Case 1
•
UL60950 recognized in US and Canada and
DEMKO certified per IEC/EN60950
•
Designed to meet Class B conducted emissions per
FCC and EN55022 when used with external filter
•
All materials meet UL94, V-0 flammability rating
Applications
•
•
•
•
Telecommunications
Data communications
Wireless communications
Servers, workstations
Benefits
•
High efficiency – no heat sink required
•
Higher current capability at 70 ºC than most
competitors’ 50 A half-bricks
Description
The QmaX Series of high current single output dc-dc converters set new standards for thermal performance and
power density in the quarter-brick package.
The 45 A QM48 converters of the QmaX Series provide outstanding thermal performance in high temperature
environments that is comparable to or exceeds the industry’s leading 50 A half-bricks. This performance is
accomplished through the use of patented/patent-pending circuit, packaging, and processing techniques to
achieve ultra-high efficiency, excellent thermal management, and a very 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 QmaX Series converters provide any standard output voltage from 3.3 V
down to 1.0 V. Outputs 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.
TM
TM
TM
MCD10073 Rev. 1.0
Page 1 of 36
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QM48T45 Family DC-DC Converter Data Sheet
36-75 VDC Input; 1.0-3.3 VDC @ 45 A Output
Electrical Specifications (common to all versions)
Conditions: TA = 25 ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, unless otherwise specified.
Parameter
Absolute Maximum Ratings
Input Voltage
Operating Ambient Temperature
Storage Temperature
Input Characteristics
Operating Input Voltage Range
Input Under Voltage Lockout
Turn-on Threshold
Turn-off Threshold
Input Voltage Transient
Isolation Characteristics
I/O Isolation
Isolation Capacitance
Isolation Resistance
Feature Characteristics
Switching Frequency
Output Voltage Trim Range
1
Notes
Continuous
Min
0
-40
-55
36
Typ
Max
80
85
125
Units
VDC
°C
°C
VDC
VDC
VDC
VDC
VDC
nF
MΩ
kHz
%
%
%
%
°C
ms
ms
VDC
VDC
VDC
VDC
48
34
32
75
35
33
100
Non-latching
33
31
100 ms
2000
1.4
10
415
Industry-std. equations (3.3-1.5 V)
Use trim equation on Page 4
(1.2-1.0 V)
Percent of V
OUT
(
NOM
)
Non-latching
Non-latching
Applies to all protection features
See Figs. F, G and H
-20
-10
117
128
125
100
4
+10
+10
+10
140
Remote Sense Compensation
1
Output Overvoltage Protection
Overtemperature Shutdown (PCB)
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)
-20
2.4
2.4
-20
0.8
20
20
0.8
Additional Notes:
1
Vout can be increased up to 10% via the sense leads or up to 10% via the trim function. However, total output voltage trim from all sources
should not exceed 10% of V
OUT
(
NOM
), in order to ensure specified operation of overvoltage protection circuitry.
MCD10073 Rev. 1.0
Page 36 of 36
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QM48T45 Family DC-DC Converter Data Sheet
36-75 VDC Input; 1.0-3.3 VDC @ 45 A Output
Operations
Input and Output Impedance
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
3.3-1.0 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.
ON/OFF (Pin 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 logic and
negative logic, with both referenced to Vin(-). A
typical connection is shown in Fig. A.
QmaX
Series
Converter
TM
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.
Remote Sense (Pins 5 and 7)
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. B).
QmaX
Series
Converter
TM
Vin (+)
Vout (+)
100
Rw
(Top View)
Vin
ON/ OFF
SENSE(+)
TRIM
SENSE(-)
10
Rload
Vin(-)
Vout(-)
Rw
Fig. B:
Remote sense circuit configuration.
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.
Vin (+)
Vout (+)
SENSE (+)
TRIM
SENSE (-)
Rload
(Top View)
Vin
ON/ OFF
Vin (-)
CONTROL
INPUT
Vout (-)
Fig. A:
Circuit configuration for ON/OFF function.
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
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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
MCD10073 Rev. 1.0
Page 3 of 36
QM48T45 Family DC-DC Converter Data Sheet
36-75 VDC Input; 1.0-3.3 VDC @ 45 A Output
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 6)
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.
The TRIM pin should be left open if trimming is not
being used. To minimize noise pickup, a 0.1µF
capacitor is connected internally between the TRIM
and SENSE(-) pins.
To increase the output voltage, refer to Fig. C. A trim
resistor, R
T-INCR
, should be connected between the
TRIM (Pin 6) and SENSE(+) (Pin 7), with a value of:
5.11(100
+
Δ)V
O
−
NOM
−
626
−
10.22
1.225Δ
(For 3.3-1.5 V)
R
T
−
INCR
=
R
T
−
INCR
84.6
=
−
7.2
Δ
120
−
9
Δ
To decrease the output voltage (Fig. D), 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
=
R
T
−
DECR
=
R
T
−
DECR
=
511
−
10.22
|
Δ
|
700
−
15
|
Δ
|
700
−
17
|
Δ
|
[kΩ] (3.3-1.5 V)
[kΩ] (1.2 V)
[kΩ] (1.0 V)
where,
R
T
−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 quarter-
bricks (except for 1.2 V and 1.0 V outputs).
[kΩ]
Vin (+)
QmaX
Series
Converter
TM
Vout (+)
SENSE(+)
TRIM
SENSE (-)
R
T- DECR
Rload
(Top View)
[kΩ]
(1.2 V)
Vin
ON/ OFF
R
T
−
INCR
=
[kΩ] (1.0 V)
Vin (-)
Vout (-)
where,
R
T
−INCR
=
Required value of trim-up resistor [kΩ]
V
O
−NOM
=
Nominal value of output voltage [V]
Fig. D:
Configuration for decreasing output voltage.
Δ
=
(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 the previous section for a complete discussion of
this requirement.
QmaX
Series
Converter
TM
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 V
OUT
(
NOM
)
, or:
[V
OUT
(
+
)
−
V
OUT
(
−
)]
−
[V
SENSE
+
)
−
V
SENSE
−
)]
≤
V
O - NOM X
10%
[V]
(
(
This equation is applicable for any condition of output
sensing and/or output trim.
Vin (+)
Vout (+)
SENSE(+)
R
T- INCR
(Top View)
Vin
ON/ OFF
TRIM
SENSE (-)
Rload
Vin(-)
Vout (-)
Fig. C:
Configuration for increasing output voltage.
MCD10073 Rev. 1.0
Page 4 of 36
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QM48T45 Family DC-DC Converter Data Sheet
36-75 VDC Input; 1.0-3.3 VDC @ 45 A Output
Protection Features
Input Undervoltage Lockout
Input undervoltage lockout is standard with this
converter. The converter will shut down when the
input voltage drops below a pre-determined voltage.
The input voltage must be typically 34 V for the
converter to turn on. Once the converter has been
turned on, it will shut off when the input voltage drops
typically below 32 V. This feature is beneficial in
preventing deep discharging of batteries used in
telecom applications.
Output Overcurrent Protection (OCP)
The converter is protected against overcurrent or
short circuit conditions. Upon sensing an overcurrent
condition, the converter will switch to constant
current operation and thereby begin to reduce output
voltage. When the output voltage drops below 60%
of its nominal value, the converter will shut down.
Once the converter has shut down, it will attempt to
restart nominally every 100 ms with a typical 1-2%
duty cycle. The attempted restart will continue
indefinitely until the overload or short circuit
conditions are removed or the output voltage rises
above 60% of its nominal value.
Once the output current is brought back into its
specified range, the converter automatically exits the
hiccup mode and continues normal operation.
Output Overvoltage Protection (OVP)
The converter will shut down if the output voltage
across Vout(+) (Pin 8) and Vout(-) (Pin 4) exceeds
the threshold of the OVP circuitry. The OVP circuitry
contains its own reference, independent of the output
voltage regulation loop. Once the converter has shut
down, it will attempt to restart every 100 ms until the
OVP condition is removed.
Overtemperature Protection (OTP)
The converter will shut down under an
overtemperature condition to protect itself from
overheating caused by operation outside the thermal
derating curves, or operation in abnormal conditions
such as system fan failure. After the converter has
cooled to a safe operating temperature, it will
automatically restart.
Safety Requirements
The converters meet North American and
International safety regulatory requirements per
UL60950 and EN60950. Basic Insulation is provided
between input and output.
To comply with safety agencies’ requirements, an
input line fuse must be used external to the converter.
The Table below provides the recommended fuse
rating for use with this family of products.
Output Voltage
3.3 V
2.5 V
2.0-1.5 V
1.2-1.0 V
Fuse Rating
10 A
7A
5A
3A
All QM converters are UL approved for a maximum
fuse rating of 15 Amps. To protect a group of modules
with a single fuse, the rating can be increased from
the recommended value above.
Electromagnetic Compatibility (EMC)
EMC requirements must be met at the end-product
system level, as no specific standards dedicated to
EMC characteristics of board mounted component
dc-dc converters exist. However, Power-One tests its
converters to several system level standards, primary
of which is the more stringent EN55022,
Information
technology
equipment
-
Radio
disturbance
characteristics-Limits and methods of measurement.
An effective internal LC differential filter significantly
reduces input reflected ripple current, and improves
EMC.
With the addition of a simple external filter, all
versions of the QmaX™ Series of converters pass the
requirements of Class B conducted emissions per
EN55022 and FCC requirements. Please contact
Power-One Applications Engineering for details of this
testing.
Fig. E:
Location of the thermocouple for thermal testing.
MCD10073 Rev. 1.0
Page 5 of 36
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