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.
RoHS Compliant
VRAF-08AT51
Non-Isolated
High Efficiency
Fixed Frequency
Low Cost
Rev.D
Under-Voltage Lockout
Output Enable
OCP/SCP
Current Source/Sink Capability
Over Voltage Protection
(Hiccup Mode)
Tracking a Reference for
Output Voltage
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
Sep. 29, 2011
Vddq/2
8 A Output
Bel Power Inc., a subsidiary of Bel Fuse Inc.
Min
-0.5 V
-0.3 V
0
C
-40
C
-
-
Typ
-
Max
15 V
5.25 V
70
C
85
C
Notes
Absolute Maximum Ratings
Parameter
Input Supply Voltage
Input Signal Voltage
Operating Temperature
Storage Temperature
Note:
All specifications are typical at 25
C
unless otherwise stated.
Input Specifications
Parameter
Operating Input Voltage
Input Current (full load)
Input Current (no load)
Reference Voltage Range (Vddq)
Remote Off Input Current
Min
10.8 V
-
-
1.2 V
-
Min
-
-
-
2.6 V
2.4 V
Typ
12 V
-
25 mA
1.8 V
7 mA
Typ
110 mA
25 mA
0.006 A s
-
-
2
Max
13.2 V
1.05 A
35 mA
1.89 V
10 mA
Max
180 mA
60 mA
0.012 A s
3.9 V
3.7 V
2
Notes
Input Specifications (continued)
Parameter
Input Reflected Ripple Current (pk-pk)
Input Reflected Ripple Current (rms)
I t Inrush Current Transient
Turn on Voltage Threshold
Turn off Voltage Threshold
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
kHz@25°C.
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
Line Regulation
Output Current
Output DC Current Limit
Output Ripple and Noise (pk-pk)
Output Ripple and Noise (rms)
Short Circuit Surge Transient
Turn on Time
Overshoot at Turn on
Output Capacitance
Min
-
-1.5%
-
-
0A
9.2 A
-
-
-
-
-
0 uF
Typ
Vddq/2
-
3 mV
3 mV
-
-
25 mV
8 mV
1.1 A s
2.5 mS
0%
-
2
Max
-
1.5%
6 mV
6 mV
8A
14 A
50 mV
15 mV
2.2 A s
5 mS
3%
2200 uF
2
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.
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
Sep. 29, 2011
Transient Response
12.5% ~ 62.5%Max Load
Settling Time
62.5% ~ 12.5%Max Load
Settling Time
V
O
=0.9 V
-
-
-
-
80 mV
30 uS
80 mV
30 uS
120 mV
50uS
120 mV
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.
Vddq/2
8 A Output
Bel Power Inc., a subsidiary of Bel Fuse Inc.
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
MTBF
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
Min
68%
260 kHz
Typ
69%
300 kHz
6,416,286 hours
Max
-
340 kHz
Notes
Vin=12 V, Vddq=1.8 V, Io=8 A
Calculated Per Bell Core SR-332 (I
O
=
80% load; Vin=12 V; T
a
= 25
C)
-
Note:
All specifications are typical at 25
C
unless otherwise stated.
Control Specifications
Parameter
Output Enable
ENABLE High
ENABLE Low
Min
2V
0V
Typ
-
-
Max
5.5 V
0.8 V
Notes
Enable Pin open, the module is off.
Efficiency Data
Efficiency Curve
85.0%
80.0%
75.0%
70.0%
65.0%
60.0%
55.0%
50.0%
45.0%
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
Efficiency
10.8 V
12.0 V
13.2 V
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.
Thermal Derating Curve
The thermal reference point Tref is shown above. For reliable operation this temperature should not exceed
115C. 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
Sep. 29, 2011
Vddq/2
8 A Output
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
京公网安备 11010802033920号
EEWORLD
