QM48T40 DC-DC Converter Data Sheet
36-75 VDC Input; 1.0-3.3 VDC @ 40 A Output
Features
•
RoHS lead-free solder and lead-solder-exempted
products are available
•
Delivers up to 40 A (132 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: 1.06 oz [30 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’ 40 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 40 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 40 A half-bricks. This performance is accomplished through the use of
patended/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
MCD10048 Rev. 1.0
Page 1 of 38
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QM48T40 DC-DC Converter Data Sheet
36-75 VDC Input; 1.0-3.3 VDC @ 40 A Output
Electrical Specifications (common to all versions)
Conditions: T
A
= 25 ºC, 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
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
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)
Continuous
Notes
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
-20
-10
117
128
125
100
4
+10
+10
+10
140
-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.
MCD10048 Rev. 1.0
Page 2 of 38
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QM48T40 DC-DC Converter Data Sheet
36-75 VDC Input; 1.0-3.3 VDC @ 40 A Output
Operation
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.
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(-). Typical connections are
shown in Fig. A.
Vin (+)
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).
Vin (+)
QmaX
Series
Converter
TM
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.
QmaX
Series
Converter
TM
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 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, 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.
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 hard wired directly to Vin(-) to enable
automatic power up of the converter without the need of an
external control signal.
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
MCD10048 Rev. 1.0
Page 3 of 38
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QM48T40 DC-DC Converter Data Sheet
36-75 VDC Input; 1.0-3.3 VDC @ 40 A Output
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 0.1 µF 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:
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
|
[k
Ω
] (For 3.3 - 1.5 V)
[k
Ω
] (1.2 V)
[k
Ω
] (1.0 V)
where,
R
T
−DECR
=
Required value of trim-down resistor [k
Ω
]
and
Δ
is as defined above.
R
T
−
INCR
=
R
T
−
INCR
=
R
T
−
INCR
=
5.11(100
+
Δ)V
O
−
NOM
−
626
−
10.22
[k
Ω
](3.3-1.5 V)
1.225Δ
84.6
−
7.2
Δ
120
−
9
Δ
[k
Ω
] (1.2V)
[k
Ω
] (1.0 V)
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).
Converters with output voltages 1.2 V and 1.0 V are
available with alternative trim feature to provide the
customers with the flexibility of second sourcing.
For 1.2 V and 1.0 V only, “T” version converter with a
character “T” in the part number uses the following trim
equations:
R
T
−
INCR
=
R
T
−
INCR
=
R
T
−
DECR
=
485
Δ
323
−
2
Δ
511
−
10.22
|
Δ
|
where,
R
T
−INCR
=
Required value of trim-up resistor [k
Ω
]
V
O
−NOM
=
Nominal value of output voltage [V]
[k
Ω
]
[k
Ω
]
[k
Ω
]
(1.2 V)
(1.0 V)
(For 1.2 V and 1.0 V)
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 previous
section for a complete discussion of this requirement.
QmaX
For 1.2 V only, “U” version converter with a character “U” in
the part number uses the following trim equations:
R
T
−
INCR
=
100
Δ
100
−
2
|
Δ
|
Vin (+)
Series
Converter
TM
Vout (+)
SENSE(+)
R
T- INCR
(Top View)
Vin
ON/ OFF
[k
Ω
]
[k
Ω
]
TRIM
SENSE (-)
Rload
Vin (-)
Vout (-)
R
T
−
DECR
=
Fig. C:
Configuration for increasing output voltage.
MCD10048 Rev. 1.0
Page 4 of 38
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QM48T40 DC-DC Converter Data Sheet
36-75 VDC Input; 1.0-3.3 VDC @ 40 A Output
Output Overvoltage Protection (OVP)
Vin (+)
QmaX
Series
Converter
TM
Vout (+)
SENSE (+)
TRIM
SENSE (-)
R
T- DECR
Rload
(Top View)
Vin
ON/ OFF
Vin (-)
Vout (-)
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.
Fig. D:
Configuration for decreasing output voltage.
Overtemperature Protection (OTP)
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]
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.
This equation is applicable for any condition of output
sensing and/or output trim.
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 at least 35 V for the converter to
turn on. Once the converter has been turned on, it will shut
off when the input voltage drops below 31 V. This feature is
beneficial in preventing deep discharging of batteries used in
telecom applications.
Output Voltage
3.3 V
2.5 -1.8 V
1.5 - 1.0 V
Fuse Rating
7.5 A
5A
3A
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 the nominal value of output
voltage, 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.
Modules are UL approved for maximum fuse rating of
15 Amps. To protect a group of modules with a single fuse,
the rating can be increased from the recommended values
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.
MCD10048 Rev. 1.0
Page 5 of 38
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