F
EATURES
•
•
•
•
•
•
•
•
•
•
•
•
•
•
–55° to +125°C operation
16 to 40 VDC input
Fully Isolated
Magnetic feedback
Fixed frequency, 600 kHz typical
Topology – Single Ended Forward
50 V for up to 50 ms transient protection
Inhibit (input & output side)
Sync function (in and out)
Output trim on single output models
Indefinite short circuit protection
Remote sense on single output models
Up to 87% efficiency / 43 W/in
3
Parallelable up to 148 watts
DC/DC C
ONVERTERS
28 V
OLT
I
NPUT
MFL SERIES
65 WATT
MODELS
VDC O
UTPUT
SINGLE
5
12
15
28
DUAL
±5
±12
±15
Size (max): 3.005 x 1.505 x 0.400 inches (76.33 x 38.23 x 10.16 mm)
See Section B8, case U1, for dimensions.
Weight:
100 grams maximum
Screening: Standard, ES, or 883 (Class H).See Section C2 for
screening options, see Section A5 for ordering information.
DESCRIPTION
The MFL Series™ 28-volt DC/DC converters are rated up to 65
watts of output power over a –55°C to +125°C temperature range
with a 28 Vdc nominal input. Up to 70% of the rated output power
can be drawn from either the positive or negative outputs. Current
sharing allows the units to be paralleled for total power of up to
148watts. The welded, hermetically sealed package is only 3.005 x
1.505 x 0.400 inches, giving the series an overall power density of
up to 43 watts per cubic inch.
I
NHIBIT
The MFL Series converters have two TTL compatible inhibit termi-
nals (INH1 and INH2) that can be used to disable power conversion,
resulting in a very low quiescent input current and no generation of
switching noise. An open collector TTL compatible low (<0.8 volts)
is required to inhibit the converter between INH1 (pin 4) and Input
Common (pin 2). An open collector TTL compatible low (<0.5 volts)
is required to inhibit the converter between INH2 (pin 12) and Output
Common (pin 8). The application of intermediate voltages to these
pins (1.5 to 10.5 volts) should be avoided.
D
ESIGN
F
EATURES
The MFL Series converters are switching regulators that use a
quasi-square wave, single ended forward converter design with a
constant switching frequency of 600 kHz.
Isolation between input and output circuits is provided with a trans-
former in the forward path and a wide bandwidth magnetic coupling
in the feedback control loop. The MFL uses a unique dual loop feed-
back technique that controls output current with an inner feedback
loop and an output voltage with a cascaded voltage mode feedback
loop.
The additional secondary current mode feedback loop improves
transient response in a manner similar to primary current mode
control and allows for ease of paralleling, but without the cost and
complexity.
The cascaded constant frequency, pulse-width modulated
converters use a quasi-square wave single-ended forward design.
Tight load regulation is achieved through a wide-bandwidth
magnetic feedback circuit. The output on single MFL models can be
trimmed (see Figure 1 for voltage changes with different resistor
values).
C
URRENT AND
P
ARALLEL
O
PERATION
Multiple MFL converters may be used in parallel to drive a common
load (see Figure 2). In this mode of operation the load current is
shared by two or three MFL converters. In current sharing mode,
one MFL converter is designated as a master. The SLAVE pin (pin
11) of the master is left unconnected and the MSTR/INH2 pin (pin
12) of the master is connected to the SLAVE pin (pin 11) of the slave
units. The units designated as slaves have the MSTR/INH2 pin (pin
12) connected to the SNS RTN pin (pin 9). Figure 2 shows the
typical setup for two or three units in parallel. Note that synchro-
nizing the units together (though shown in the figure) is not required
for current sharing operation. A second slave unit may be placed in
parallel with a master and slave; this requires the TRI pin (pin 3) of
the master unit to be connected to the SNS RTN pin (pin 9).
When paralleled, 76% of the total combined power ratings of the
MFL converters are available at the load. Overload and short circuit
performance are not adversely affected during parallel operation.
B2-25
MFL SERIES
65 WATT
ABSOLUTE MAXIMUM RATINGS
Input Voltage
• 16 to 40 VDC
Power Dissipation (Pd)
• 14 watts (16 watts MFL2805S, MFL2805D)
Output Power
• 50 to 65 watts depending on model
Lead Soldering Temperature (10 sec per lead)
• 300°C
Storage Temperature Range (Case)
• –65°C to +150°C
DC/DC C
ONVERTERS
SYNC AND INHIBIT (INH1, INH2)
Sync In (525 to 675 kHz)
• Duty cycle 40% min, 60% max
• Logic low 0.8 V max
• Logic high 4.5 V min, 9 V max
• Referenced to input common
• If not used, connect to input common
Sync Out
• Referenced to input common
Inhibit (INH1, INH2) TTL Open Collector
• Logic low (output disabled)
INH1 referenced to input common
Logic low 0.8 V max
Inhibit pin current 10 mA max
INH2 referenced to output common
Logic low 0.5 V max
Inhibit pin current 5 mA max
• Logic high (output enabled)
Open collector
TYPICAL CHARACTERISTICS
Output Voltage Temperature Coefficient
• 100 ppm/°C typical
Input to Output Capacitance
• 150 pF, typical
Isolation
• 100 megohm minimum at 500 V
Audio Rejection
• 50 dB typical
Conversion Frequency
• Free run mode 600 kHz typical
550 kHz. min, 650 kHz max
• External sync range 525 to 675 kHz
Inhibit Pin Voltage (unit enabled)
• INH1 = 9 to12 V, INH2 = 6 to 9 V
RECOMMENDED OPERATING CONDI-
Input Voltage Range
TIONS
• 16 to 40 VDC continuous
• 50 V for 120 msec transient
Case Operating Temperature (Tc)
• –55°C to +125°C full power
• –55°C to +135°C absolute
Derate Output Power/Current
• Linearly from 100% at 125°C to 0% at 135°C
PINS NOT USED
TR1, Master, and Slave
If not used, leave unconnected
Electrical Characteristics: –55°C to +125° C
1
Tc, 28 VDC Vin, 100% load, free run, unless otherwise specified.
SINGLE OUTPUT MODELS
PARAMETER
OUTPUT VOLTAGE
OUTPUT CURRENT
OUTPUT POWER
OUTPUT RIPPLE
VOLTAGE 10 k - 2 MHz
LINE REGULATION
LOAD REGULATION
INPUT VOLTAGE
NO LOAD TO FULL
INPUT CURRENT
CONDITION
Tc = 25°C
V
IN
= 16 TO 40 VDC
V
IN
= 16 TO 40 VDC
Tc = 25°C
Tc = –55°C to +125°C
V
IN
= 16 to 40 VDC
NO LOAD TO FULL
CONTINUOUS
TRANSIENT
2
50 ms
NO LOAD
FULL LOAD
INHIBITED - INH1
INHIBITED - INH2
INPUT RIPPLE
CURRENT
EFFICIENCY
LOAD FAULT
3
10 kHz - 10 MHz
Tc = 25°C
POWER DISSIPATION
SHORT CIRCUIT
Tc = 25°C
RECOVERY
STEP LOAD RESP.
50% – 100% – 50%
TRANSIENT
RECOVERY
4
16 – 40 – 16 VDC
TRANSIENT
5
RECOVERY
4
DELAY
OVERSHOOT
MFL2805S
MIN
4.95
0
0
—
—
—
—
16
—
—
—
—
—
—
77
TYP MAX
5.00 5.05
—
—
15
30
0
0
28
—
70
—
9
35
15
80
10
50
35
50
20
20
40
50
120
2.5
14
70
50
—
MFL2812S
MIN TYP MAX
11.88 12.00 12.12
0
0
—
—
—
—
16
—
—
—
—
—
—
83
—
—
30
45
0
0
28
—
50
—
9
35
15
86
5
60
75
100
20
20
40
50
80
2.8
14
70
50
—
MFL2815S
MIN TYP MAX
14.85 15.00 15.15
0
0
—
—
—
—
16
—
—
—
—
—
—
84
—
—
30
45
0
0
28
—
50
—
9
35
15
87
4.33
65
85
110
20
20
40
50
80
3.0
14
70
50
—
MFL2828S
1
MIN TYP MAX
1
27.72 28.00 28.28
0
0
—
—
—
—
16
—
—
—
—
—
—
83
—
—
100
—
20
20
28
—
60
—
9
35
20
86
2.32
65
200
—
60
75
40
50
100
2.8
14
70
50
—
mA pp
%
UNITS
VDC
A
W
mV p-p
mV
mV
VDC
V
mA
A
mA
—
—
—
—
—
—
—
—
12.5
1.5
250
1.5
250
200
3.5
0
16
4
350
3.0
300
300
6
25
—
—
—
—
—
—
—
—
10
1.5
450
1.5
250
200
3.5
0
14
4
600
3.0
400
300
6
50
—
—
—
—
—
—
—
—
10
1.5
500
1.5
250
200
3.5
0
14
4
600
3.0
400
300
6
50
—
—
—
—
—
—
—
—
7
1.0
14
4
A
ms
mV pk
ms
mV pk
µs
ms
mV pk
800 1400
1.5
3.0
250
200
3.5
0
800
400
6
100
STEP LINE RESP.
START-UP
Notes
1. MFL2828S specifiications are at 25°Tc, contact your Interpoint repre-
sentative for more information.
2. Unit will shut down above approximately 45V but will be undamaged and
will restart when voltage drops into normal range.
3. Indefinite short circuit protection not guaranteed above 125°C case.
4. Recovery time is measured from application of the transient to point at
which Vout is within 1% of final value.
5. Transition time
≥
10 µs.
B2-26
DC/DC C
ONVERTERS
DUAL OUTPUT MODELS
PARAMETER
OUTPUT VOLTAGE
OUTPUT CURRENT
1
V
IN
= 16 TO 40 VDC
OUTPUT POWER
OUTPUT RIPPLE
VOLTAGE +/– V
OUT
LINE REGULATION
V
IN
= 16 TO 40 VDC
LOAD REGULATION
NO LOAD TO FULL
CROSS REGULATION
Tc = 25°C
INPUT VOLTAGE
NO LOAD TO FULL
INPUT CURRENT
Tc = 25°C
10 kHz - 2 MHz
+V
OUT
–V
OUT
+V
OUT
–V
OUT
SEE NOTE 2
SEE NOTE 3
CONTINUOUS
TRANSIENT
4
50 ms.
NO LOAD
FULL LOAD
INHIBITED - INH1
INHIBITED - INH2
10 kHz - 10 MHz
BALANCED LOAD
POWER DISSIPATION
SHORT CIRCUIT
RECOVERY
50 %–100%– 50% LOAD
TRANSIENT
RECOVERY
6
16 – 40 – 16 V
IN
TRANSIENT
7
RECOVERY
6
START–UP
DELAY
OVERSHOOT
—
—
—
—
—
—
—
16
0
—
—
—
—
—
77
—
—
—
—
—
—
—
—
50
0
25
0
25
5
3
28
—
50
—
9
35
15
80
12.5
1.5
250
1.5
250
200
3.5
0
6
40
50
120
14
70
50
—
16
4.0
350
3.0
300
300
6
25
100
50
100
50
100
8
—
—
—
—
—
—
—
16
0
—
—
—
—
—
83
—
—
—
—
—
—
—
—
50
0
25
10
50
2
2
28
—
50
—
9
35
15
86
10
1.5
450
1.5
250
200
3.5
0
4
40
50
100
2.80
14
70
50
—
14
4.0
600
3.0
400
300
6
50
120
50
100
100
120
4
—
16
0
—
—
—
—
—
84
—
—
—
—
—
—
—
—
—
—
—
—
—
—
2
28
—
50
—
9
35
15
87
10
1.5
500
1.5
250
200
3.5
0
50
0
25
10
50
2
4
40
50
100
3.00
14
70
50
—
14
4.0
600
3.0
400
300
6
50
150
50
100
100
150
4
CONDITIONS
+V
OUT
Tc = 25°C
–V
OUT
EACH OUTPUT
TOTAL OUTPUT
V
IN
= 16 TO 40 VDC
MFL2805D
MIN TYP MAX
4.95 5.00 5.05
4.92 5.00 5.08
0
0
0
—
—
—
7
10
50
MFL2812D
MIN TYP MAX
11.88 12.00 12.12
11.82 12.00 12.18
0
0
0
—
—
—
3.5
5
60
MFL2815D
MIN TYP MAX
14.85 15.00 15.15
14.77 15.00 15.23
0
0
0
—
—
—
3.03
4.34
65
MFL SERIES
65 WATT
UNITS
VDC
A
W
Electrical Characteristics: –55°C to +125°C Tc, 28 VDC Vin, 100% load, free run, unless otherwise specified.
mV p-p
mV
mV
%
VDC
V
mA
A
mA
mA p-p
%
W
ms
mV pk
ms
mV pk
µs
ms
mV p
INPUT RIPPLE
CURRENT
EFFICIENCY 25°C Tc
LOAD FAULT
5
Tc = 25°C
STEP LOAD
RESPONSE ± V
OUT
STEP LINE
RESPONSE ± V
OUT
Notes
1. Up to 70% of the total output power is available from either output providing
the opposite output is simultaneously carrying 30% of the total power.
2. Effect on the
negative output under the following conditions:
+P
out
30% to 70%; –P
out
70% to 30%
3. Effect on the
negative output under the following conditions:
+P
out
50%; –P
out
10% to 50%
4. Unit will shut down above approximately 45V but will be undamaged and will
restart when voltage drops into normal range.
5. Indefinite short circuit protection not guaranteed above 125°C case.
6. Recovery time is measured from application of the transient to point at which
Vout is within 1% of final value.
7. Transition time
≥
10 µs.
B2-27
MFL SERIES
65 WATT
28V
+
–
DC/DC C
ONVERTERS
SINGLE OUTPUT MODELS CONNECTION DIAGRAMS - SENSE AND PARALLEL
1
2
3
Inhibit
Sync In
4
5
6
MSTR/INH2 12
Slave 11
Pos. Sense 10
9
Sense Return
8
Output Common
7
Positive Output
Positive Input
Input Common
TR1
INH1
Sync Out
Sync In
–
+
RL
REMOTE SENSE CONNECTION
1
2
3
Inhibit
Sync In
4
5
6
MSTR/INH2 12
11
Slave
10
Pos. Sense
9
Sense Return
8
Output Common
7
Positive Output
28V
+
–
Positive Input
Input Common
TR1
INH1
Sync Out
Sync In
RA
–
+
RL
OUTPUT VOLTAGE ADJUST CONNECTION
VOUT INCREASE
(VOLT)
0.1
0.2
0.3
0.4
0.5
RA (OHMS)
12–V 15–V
25
20
50
75
100
125
40
60
80
100
5–V
70
140
210
280
350
F
IGURE
1: S
ENSE
C
ONNECTIONS AND
T
RIM
T
ABLE
28V
+
–
1
2
3
4
5
6
Positive Input
Input Common
TR1
INH1
Sync Out
Sync In
MSTR/INH2 12
Slave 11
Pos. Sense
Sense Return
10
9
8
7
+
RL
–
Inhibit
Sync In
MASTER
Output Common
Positive Output
CONNECT ONLY WHEN 2 SLAVES ARE USED
1
2
3
4
5
6
Positive Input
Input Common
TR1
INH1
Sync Out
Sync In
MSTR/INH2 12
Slave 11
Pos. Sense 10
Sense Return 9
Output Common 8
7
Positive Output
SLAVE 1
1
2
3
4
5
6
Positive Input
Input Common
TR1
INH1
Sync Out
Sync In
MSTR/INH2 12
Slave 11
Pos. Sense 10
Sense Return 9
SLAVE 2
Output Common 8
7
Positive Output
F
IGURE
2: P
ARALLEL
C
ONNECTIONS
B2-28
DC/DC C
ONVERTERS
PIN OUT
Pin
1
2
3
4
5
6
7
8
9
10
11
12
Single Output
Positive Input
Input Common
Triple (TRI)
Inhibit 1 (INH1)
Sync Out
Sync In
Positive Output
Output Common
Sense Return
Positive Sense
Slave
Master/ Inhibit 2
Dual Output
Positive Input
Input Common
Triple (TRI)
Inhibit 1 (INH1)
Sync Out
Sync In
Positive Output
Output Common
Negative Output
No connection
Slave
Master / Inhibit 2
Angled corner indicates pin one.
MFL SERIES
65 WATT
1
2
3
4
5
6
12
11
TOP VIEW
MFL
(Pin side, marked side)
10
9
8
7
See Section B8, case U1, for dimensions.
Pin 6 should be connected to input common if
external sync (Sync In) is not used.
Sense pins must be connected to their respective
outputs if not used.
F
IGURE
3: P
IN
O
UT
SMD NUMBERS
MODEL NUMBERING KEY
MFL
Base Model
Input Voltage
Output Voltage
Number of Outputs
(S = single, D = dual)
Screening
(Standard screening has no designator
in this position.)
28 05 S / ES
S
TANDARD
M
ICROCIRCUIT
D
RAWING
(SMD)
5962-9316301HXC
5962-9316201HXC
5962-9316101HXC
IN PROCESS
5962-9319101HXC
5962-9319201HXC
5962-9319301HXC
MFL S
ERIES
S
IMILAR
P
ART
MFL2805S/883
MFL2812S/883
MFL2815S/883
MFL2828S/883
MFL2805D/883
MFL2812D/883
MFL2815D/883
For exact specifications for an SMD product, refer to the
SMD drawing. See Section A3, SMDs, for more information.
Typical Performance Curves: 25°C Tc , 28 VDC Vin, 100% load, free run, unless otherwise specified.
90
85
16V
90
85
16V
90
85
16V
Efficiency (%)
Efficiency (%)
Efficiency (%)
80
75
28V
80
75
70
65
28V
80
75
70
65
40V
28V
40V
70
65
60
10
20
30
40
50
40V
Output (Watts)
60
10
20
30
40
50
60
60
10
20
30
40
50
60 65
Output Power (Watts)
Output Power (Watts)
MFL2805S & MFL2805D Efficiency
MFL2812S & MFL2812D Efficiency
MFL2815S & MFL2815D Efficiency
F
IGURE
4
F
IGURE
5
F
IGURE
6
B2-29
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