BEL VRAF

NON-ISOLATED DC/DC CONVERTERS
12 Vdc Input
Vddq/2
8 A Output
Bel Power Inc., a subsidiary of Bel Fuse Inc.
Sep. 29, 2011
VRAF-08AT51
RoHS Compliant
Rev.D

Non-Isolated

Under-Voltage Lockout

High Efficiency

Output Enable

Fixed Frequency

OCP/SCP

Low Cost

Current Source/Sink Capability

Tracking a Reference for
Output Voltage

Over Voltage Protection
(Hiccup Mode)

High Power Density
Description
The Bel VRAF-08AT51 module is a non-isolated, step down dc/dc power converter that operates from a nominal
12 Vdc or wide range 10.8 Vdc to 13.2 Vdc source. This converter is designed specifically to provide bus
termination voltages in applications such as DDR (double data rate) memory where the bus termination voltage
must closely track the I/O bus voltage. The converter accepts a reference input and uses this to program its
output voltage to 50% of the reference. The unit is packaged in compact single-in-line footprint and provides a
maximum 8 A output. Standard features include remote on/off, input under-voltage lockout, output over voltage
protection.
Part Selection
Output
Voltage
0.9 V
Input Voltage
10.8 V - 13.2 V
Max. Output
Current
8A
Max. Output
Power
7.2 W
Typical
Efficiency
69%
Model Number
VRAF-08AT51
Notes: 1. All part numbers above indicate RoHS 6. Change the second letter "R" to "7" for RoHS 5 part numbers.
2. Add “G” suffix at the end of the model numbers listed above to indicate “Tray Packaging”.
Part Number Explanation
V R AF – 08 A T5 1
1 2
3
4 5 6
7
1---Vertical Mount
2---RoHS 6, change “R” to “7” means RoHS 5
3---0.65"x0.41" DDR
4---Output current 8A
5---12V narrow range, 10.8-13.2V
6---Vout =0.5Vddq
7---Option
Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302  Tel 201-432-0463  Fax 201-432-9542  www.belfuse.com
NON-ISOLATED DC/DC CONVERTERS
12 Vdc Input
Vddq/2
8 A Output
Bel Power Inc., a subsidiary of Bel Fuse Inc.
Sep. 29, 2011
Absolute Maximum Ratings
Min
Typ
Max
Input Supply Voltage
Parameter
-0.5 V
-
15 V
Input Signal Voltage
-0.3 V
Operating Temperature
Storage Temperature
Notes
5.25 V
0 C
-
70 C
-40 C
-
85 C
Note: All specifications are typical at 25 C unless otherwise stated.
Input Specifications
Parameter
Min
Typ
Max
Operating Input Voltage
10.8 V
12 V
13.2 V
Input Current (full load)
-
-
1.05 A
Input Current (no load)
-
25 mA
35 mA
1.2 V
1.8 V
1.89 V
-
7 mA
10 mA
Parameter
Min
Typ
Max
Input Reflected Ripple Current (pk-pk)
-
110 mA
180 mA
Input Reflected Ripple Current (rms)
-
25 mA
60 mA
I t Inrush Current Transient
-
0.006 A s
0.012 A s
Turn on Voltage Threshold
2.6 V
-
3.9 V
Turn off Voltage Threshold
2.4 V
-
3.7 V
Reference Voltage Range (Vddq)
Remote Off Input Current
Notes
Input Specifications (continued)
2
2
Notes
With simulated source impedance
of 1000 nH, 5 Hz to 20 MHz. Use a
100 uF/25 V Tan cap with
ESR=0.025 ohm max, at 100
[email protected]°C.
2
Notes: 1. All specifications are typical at 25 C unless otherwise stated.
2. This power module is not internally fused. An input line fuse must always be used.
Output Specifications
Parameter
Output Voltage Set Point
Tracking Tolerance
(Vddq/2-Vout)/Vout
Load Regulation
Min
-
Typ
Vddq/2
Max
-
-1.5%
-
1.5%
-
3 mV
6 mV
Line Regulation
-
3 mV
6 mV
Output Current
0A
-
8A
Output DC Current Limit
9.2 A
-
14 A
Output Ripple and Noise (pk-pk)
-
25 mV
50 mV
Output Ripple and Noise (rms)
-
8 mV
15 mV
Short Circuit Surge Transient
-
1.1 A s
2
2.2 A s
Turn on Time
-
2.5 mS
5 mS
-
0%
3%
0 uF
-
2200 uF
Overshoot at Turn on
Output Capacitance
Notes
Vin=12 V, lout=full load
Test conditions:
0-20 MHz BW, with 13 X 10uF
0603 ceramics + 1 X 47uF 1206
ceramic at the output.
2
Start up from ENABLE.
Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302  Tel 201-432-0463  Fax 201-432-9542  www.belfuse.com
NON-ISOLATED DC/DC CONVERTERS
12 Vdc Input
Vddq/2
8 A Output
Bel Power Inc., a subsidiary of Bel Fuse Inc.
Sep. 29, 2011
Transient Response
12.5% ~ 62.5%Max Load
Settling Time
62.5% ~ 12.5%Max Load
VO =0.9 V
Settling Time
-
80 mV
120 mV
-
30 uS
50uS
-
80 mV
120 mV
-
30 uS
50 uS
di/dt=1A/uS; Vin12 V; and with
13 X 10uF 0603 ceramics + 1
X 47uF 1206 ceramic at the
output. Vddq=1.5V.
Note: All specifications are typical at Vin =12 V, Vddq=1.8 V, Io=8 A, Ta= 25°C unless otherwise stated.
General Specifications
Parameter
Efficiency
Switching Frequency
Min
68%
260 kHz
Typ
69%
300 kHz
MTBF
Max
340 kHz
Notes
Vin=12 V, Vddq=1.8 V, Io=8 A
Calculated Per Bell Core SR-332 (IO =
80% load; Vin=12 V; Ta = 25 C)
6,416,286 hours
Dimensions
Inches (L × W × H)
Millimeters (L × W × H)
Weight
-
0.65 x 0.41 x 0.40
16.51 x 10.41 x 10.16
2.5 g
-
Note: All specifications are typical at 25 C unless otherwise stated.
Control Specifications
Parameter
Output Enable
Min
Typ
Max
ENABLE High
2V
-
5.5 V
ENABLE Low
0V
-
0.8 V
Notes
Enable Pin open, the module is off.
Efficiency Data
Efficiency
Efficiency Curve
85.0%
80.0%
75.0%
70.0%
65.0%
60.0%
55.0%
50.0%
45.0%
10.8 V
12.0 V
13.2 V
0.8
2.0
4.0
6.0
8.0
Output Current (A)
VRAF-08AT51
Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302  Tel 201-432-0463  Fax 201-432-9542  www.belfuse.com
NON-ISOLATED DC/DC CONVERTERS
12 Vdc Input
Vddq/2
Sep. 29, 2011
8 A Output
Bel Power Inc., a subsidiary of Bel Fuse Inc.
Thermal Derating Curve
The thermal reference point Tref is shown above. For reliable operation this temperature should not exceed
115C. The output power of the module should not exceed the rated power for the module.
Vin=12 V, Vddq=1.8 V
Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302  Tel 201-432-0463  Fax 201-432-9542  www.belfuse.com
NON-ISOLATED DC/DC CONVERTERS
12 Vdc Input
Vddq/2
8 A Output
Sep. 29, 2011
Bel Power Inc., a subsidiary of Bel Fuse Inc.
Ripple and Noise Waveform
Note: Ripple and noise at Vin=12 V, Vddq=1.5 V, Io=8 A, with 13 X 10uF 0603 ceramics + 1 X 47uF 1206 ceramic at
the output, Ta=25 C.
Transient Response Waveforms
12.5% to 62.5% load step at Vin=12 V, Vddq=1.5V
62.5% to 12.5% load step at Vin=12 V, Vddq=1.5V
Note: Transient response at di/dt=1A/uS, with 13 X 10uF 0603 ceramics + 1 X 47uF 1206 ceramic at the output,
Ta=25 C.
Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302  Tel 201-432-0463  Fax 201-432-9542  www.belfuse.com
NON-ISOLATED DC/DC CONVERTERS
12 Vdc Input
Sep. 29, 2011
Vddq/2
8 A Output
Bel Power Inc., a subsidiary of Bel Fuse Inc.
Output Tracking
Test condition: Vin=12 V, Vddq=1.8 V, Io=8 A.
Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302  Tel 201-432-0463  Fax 201-432-9542  www.belfuse.com
NON-ISOLATED DC/DC CONVERTERS
12 Vdc Input
Vddq/2
Sep. 29, 2011
8 A Output
Bel Power Inc., a subsidiary of Bel Fuse Inc.
Mechanical Outline
Pin Connections
Pin
Function
1
Vin
2
Vddq
3
Vout
4
GND
5
Enable
Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302  Tel 201-432-0463  Fax 201-432-9542  www.belfuse.com
NON-ISOLATED DC/DC CONVERTERS
12 Vdc Input
Vddq/2 / 8 A Output
Bel Power Inc., a subsidiary of Bel Fuse Inc.
Sep. 29, 2011
Revision History
Date
Revision
Changes Detail
Approval
2011-08-19
A
First Release
HL
2011-8-23
B
Update transient response
HL
2011-8-30
C
Update transient response
HL
2011-9-29
D
Update input range
HL
RoHS Compliance
Complies with the European Directive 2002/95/EC, calling for the elimination of lead and
other hazardous substances from electronic products.
2011 Bel Fuse Inc. Specifications subject to change without notice. 092911
CORPORATE
FAR EAST
EUROPE
Bel Fuse Inc.
206 Van Vorst Street
Jersey City, NJ 07302
Tel 201-432-0463
Fax 201-432-9542
www.belfuse.com
Bel Fuse Ltd.
8F/ 8 Luk Hop Street
San Po Kong
Kowloon, Hong Kong
Tel 852-2328-5515
Fax 852-2352-3706
www.belfuse.com
Bel Fuse Europe Ltd.
Preston Technology Management Centre
Marsh Lane, Suite G7, Preston
Lancashire, PR1 8UD, U.K.
Tel 44-1772-556601
Fax 44-1772-888366
www.belfuse.com