CUI VHB75W-Q24-S15

rev.
description
features
The VHB75W series of DC-DC converters
are designed for high reliability
applications, featuring over-temperature
protection, over-current protection. The
wide 4:1 input range (9-36V or 18-75V) is
very useful to stabilize an input source
like batteries in various discharging and
charging conditions. Additionally, high
efficiency, fast response, tight
regulations, remote sense and remote
On/Off control make these converters
very useful in many applications.
·37.5-75W isolated output
·Efficiency to 85%
·300 kHz switching frequency
·regulated output
·continuous short circuit
protection
·industry standard half-brick size
·remote on/off
·over-temperature protection
·over-current protection
input voltage
nominal
range
(V dc)
(V dc)
VHB75W-Q24-S3R3
VHB75W-Q24-S5
VHB75W-Q24-S12
VHB75W-Q24-S15
VHB75W-Q24-S24
VHB75W-Q24-S48
VHB75W-Q48-S3R3
VHB75W-Q48-S5
VHB75W-Q48-S12
VHB75W-Q48-S15
VHB75W-Q48-S24
VHB75W-Q48-S48
notes:
1 of 10
date
date
04/2011
DESCRIPTION: half-brick dc-dc converter
PART NUMBER: VHB75W
MODEL
page
page
24
24
24
24
24
24
48
48
48
48
48
48
output
voltage
(V dc)
9.0~36.0
9.0~36.0
9.0~36.0
9.0~36.0
9.0~36.0
9.0~36.0
18.0~75.0
18.0~75.0
18.0~75.0
18.0~75.0
18.0~75.0
18.0~75.0
3.3
5
12
15
24
48
3.3
5
12
15
24
48
output
current 1
(A)
15
15
6.25
5
3.12
1.56
15
15
6.25
5
3.12
1.56
input current
no load 2
full load 2
(mA)
(mA)
50
50
50
50
50
50
50
50
50
50
50
50
2611
3811
3765
3720
3720
3811
1320
1905
1860
1860
1860
1860
efficiency
typ. 3
(%)
79
82
83
84
84
82
80
83
84
85
85
84
1. see output derating (page 4)
2. input currents are measured at nominal input voltage
3. efficiency is measured at nominal line, full load
INPUT
parameter
input voltage range
conditions/description
under voltage lockout
remote on/off control 4
24 Vin power up
24 Vin power down
48 Vin power up
48 Vin power down
section 15 in the application notes
input filter
PI type
notes:
min
9
18
nom
24
48
8.8
8
17
16
max
36
75
units
V dc
V dc
V dc
V dc
V dc
V dc
4. add suffix “N” to the model number for negative logic on/off control
*V-Infinity reserves the right to make changes to its products or to discontinue any product or service without notice, and to advise customers to verify the most up-todate product information before placing orders. V-Infinity assumes no liability or responsibility for customer’s applications using V-Infinity products other than repair
or replacing (at V-I’s option) V-Infinity products not meeting V-I’s published specifications. Nothing will be covered outside of standard product warranty.
20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2383
www.v-infinity.com
page
2 of 10
date
04/2011
DESCRIPTION: half-brick dc-dc converter
PART NUMBER: VHB75W
OUTPUT
parameter
voltage accuracy
transient response
external trim adj. range
ripple & noise (20MHz BW)
conditions/description
min
nom
25% step load change
3.3V, 5V
12V& 15V
24V
48V
temperature coefficient
short circuit protection
continuous
line regulation 5
load regulation 6
over voltage protection trip range, % Vo nom.
over current protection
% nominal output current
max
±1
<500
±10
40
100
60
150
100
240
200
480
units
%
μ sec
%
mV RMS
mV p-p
mV RMS
mV p-p
mV RMS
mV p-p
mV RMS
mV p-p
%/°C
±0.2
±0.2
140
160
%
%
%
%
max
units
KHz
°C
°C
°C
±0.03
115
110
GENERAL SPECIFICATIONS
parameter
switching frequency
operating ambient temp. 7
storage temperature
thermal shutdown case temp.
case material
conditions/description
min
nom
300
-40
-55
100
105
100
aluminum
ISOLATION SPECIFICATIONS
parameter
isolation voltage
conditions/description
input/output
input/case
min
1500
1500
output/case
1500
100
isolation resistance
notes:
5.
6.
7.
nom
max
units
V dc
V dc
V dc
MΩ
measured from high line to low line at full load
measured from full load to zero load at nominal input
see output derating curve (page 4)
*V-Infinity reserves the right to make changes to its products or to discontinue any product or service without notice, and to advise customers to verify the most up-todate product information before placing orders. V-Infinity assumes no liability or responsibility for customer’s applications using V-Infinity products other than repair
or replacing (at V-I’s option) V-Infinity products not meeting V-I’s published specifications. Nothing will be covered outside of standard product warranty.
20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2383
www.v-infinity.com
PART NUMBER: VHB75W
page
3 of 10
date
04/2011
DESCRIPTION: half-brick dc-dc converter
MECHANICAL DRAWING
20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2383
www.v-infinity.com
PART NUMBER: VHB75W
page
4 of 10
date
04/2011
DESCRIPTION: half-brick dc-dc converter
APPLICATION NOTES
1. OUTPUT DE-RATING
The operating case temperature range for VHB75W is -40 ~ +100°C. When operating the VHB75W series, proper derating or cooling
is needed. The maximum case temperature under any operating condition should not exceed 100°C.
Power Dissipated vs Ambient Temperature and Air Flo w
Power Disspated ,Pd(Watts)
Natural Convection
20 ft./min. (0.1 m/s)
100 ft./min. (0.5 m/s)
200 ft./min. (1.0 m/s)
300 ft./min. (1.5 m/s)
400 ft./min. (2.0 m/s)
500 ft./min. (2.5 m/s)
600 ft./min. (3.0 m/s)
700 ft./min. (3.5 m/s)
800 ft./min. (4.0 m/s)
Ambient Temperature ,Ta(Deg. C)
FIGURE 1. OUTPUT DERATING (FORCED CONVECTION WITH NO HEAT SINK)
Example:
What is the minimum airflow necessary for a VHB75W-Q48-S12
operating at nominal line, an output current of 6.25 A, and a
maximum ambient temperature of 40°C?
Solution:
Given: Vin=48 V dc, Vo=12 V dc, Io=6.25 A
Determine Power dissipation (Pd):
Pd=Pi-Po=Po(1-η)/η
Pd=12×6.25×(1-0.84)/0.84=14.29 W
Determine airflow:
Given: Pd=14.29 W and Ta=40°C
Check above Power de-rating curve:
minimum airflow= 400 ft./min.
Verifying:
AIR FLOW RATE
Natural Convection
20ft./min. (0.1m/s)
TYPICAL Rca
7.12
/W
100 ft./min. (0.5m/s)
6.21
/W
200 ft./min. (1.0m/s)
5.17
/W
300 ft./min. (1.5m/s)
4.29
/W
400 ft./min. (2.0m/s)
3.64
/W
500 ft./min. (2.5m/s)
2.96
/W
600 ft./min. (3.0m/s)
2.53
/W
700 ft./min. (3.5m/s)
2.37
/W
800 ft./min. (4.0m/s)
2.19
/W
Chart of Thermal Resistance vs Air Flow
The maximum temp. rise ΔT = Pd × Rca=14.29×3.64=52.02°C. The maximum case temperature Tc=Ta+ΔT=92.02°C<100°C
Where:
The Rca is thermal resistance from case to ambience.The Ta is ambient temperature and the Tc is case temperature.
20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2383
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page
5 of 10
date
04/2011
DESCRIPTION: half-brick dc-dc converter
PART NUMBER: VHB75W
2. INPUT VOLTAGE RANGE
It is important to ensure the input voltage measured at the converter input pins is within the range for that converter. Make sure wire
losses and voltage ripples are accounted for. One possible problem is driving the converter with a linear unregulated power supply.
For example, if the average voltage measured by a DMM is 9V, with a voltage ripple of 3Vpp, the actual input can swing from 7.5V to
10.5V. This will be outside the specified input range of 9-36V and the converter may not function properly. On the other end, make
sure the actual input voltage does not exceed the highest voltage of 36V or 75V.
3. LEAD WIRES
Make sure the input and output wires are of adequate AWG size to minimize voltage drop, and ensure the voltage across the input
terminals is above the converter's rated minimum voltage at all times. It is recommended to have the wire pairs twisted, respectively
for the input pair and the output pair, so as to minimize noise pickup.
4. INPUT CURRENT
The input voltage source must be able to provide enough current to the converter, otherwise it may not start up or operate properly. A
typical symptom is not starting or unusually low output voltage. In general, it is recommended to be able to provide at least:
η *Vmin) where Pout is the maximum output power, Vmin is the minimum input voltage and η is the converter's
Ipeak = 150%*Pout/(η
efficiency. As an example, for VHB75W-Q24-S5 to operate with 9~36 V input, 75 W output and an efficiency of 82%, the minimum
source current is recommended to be: Ipeak = 150% * 75 / (82% * 9) = 15.24 A.
5. INPUT FUSE
To limit the input current and to facilitate input reversal protection and input OVP protection, a fast-acting input fuse is recommended
for the input line. The fuse rating will depend on the input range and should allow for the maximum current at the lowest input voltη *Vmin).
age, as shown in this equation: Ipeak = 150%*Pout/(η
In the previous example of VHB75W-Q24-S5, the peak input current at 9V was calculated to be 15.24 A. A 20 A fuse may be suitable
for this application. Make sure the fuse voltage rating is higher than the maximum input voltage.
6. REMOTE SENSE
The converter provides regulated outputs at the output terminals. When there is a large current and/or the output cable is of some
length, the voltage at the end of the output cable may be noticeably lower than at the terminals. The converter can compensate up to
0.5V of voltage drop through remote sense terminals. To ensure accurate regulation, run two separate wires (twisted) from the
desired regulation points to the remote sense terminals, as shown below. Even if the load current is low, still connect +Vo to +S and
-Vo to -S.
+Vo
+S
(+)
Load
Trim
(-)
-S
-Vo
FIGURE 2. REMOTE SENSE
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date
04/2011
DESCRIPTION: half-brick dc-dc converter
PART NUMBER: VHB75W
7. OUTPUT TRIMMING (OPTIONAL)
The output voltages are preset to nominal values as indicated by the models table at the factory. If desired, the output voltage may
optionally be trimmed to a different value (+/- 10%) with external resistors and/or potentiometer as shown below.
+Vo
+Vin
+S
FIGURE 3. TRIMMING WITH
10KΩ
Trimpot
Trim
EXTERNAL POTENTIOMETER
R load
-S
-Vin
-Vo
To trim the output voltage with fixed resistors, the output voltage can be calculated as follows.
Trim-Up
+Vin
Trim-Down
+Vo
+Vin
+Vo
R trim-down
Trim
Trim
R load
R load
R trim-up
-Vin
-Vo
-Vin
-Vo
FIGURE 4: TRIM-UP VOLTAGE SETUP
FIGURE 5: TRIM-DOWN VOLTAGE SETUP
The value of R trim-up is defined as:
The value of R trim-down is defined as:
Rtrim-up =
R1 - R2 x (Vo - Vo, nom)
(KΩ)
Vo - Vo, nom
Rtrim-down =
R1 - R2 x (Vo, nom - Vo)
(KΩ)
Vo, nom - Vo
Where: R trim-up is the external resistor in K Ω . V o,nom is the
Where: R trim-down is the external resistor in K Ω . V o,nom is the
nominal output voltage. V o is the desired output voltage. R 1 ,
nominal output voltage. V o is the desired output voltage. R 1 ,
R 2 , R 3 , V r , and V f are internal to the unit and are defined in
R 2 , and V r are internal to the unit and are defined in
Table 1. For example, to trim-up the output voltage of 5.0V
Table 1. For example, to trim-up the output voltage of 5.0V
module (VHB75W-Q48-S5) by 8% to 5.4V, R trim-up is calculated
module (VHB75W-Q48-S5) by 8% to 4.6V, R trim-down is calculated
as follows:
Vo - Vo, nom = 5.4 - 5.0 = 0.4 V
as follows:
Vo, nom - Vo = 5.0 - 4.6 = 0.4 V
R1 = 5.8 KΩ
R1 = 5.8 KΩ
R2 = 8.2 KΩ
R2 = 10.52 KΩ
Rtrim-up =
Table 1
3.3V
5V
12V
15V
24V
48V
5.8 - 8.2 x 0.4
= 6.3 (KΩ)
0.4
Ω
3.168
5.8
19.656
25.474
42.33
74.514
Ω
7.2
8.2
13.304
14.76
16.67
13.0476
Rtrim-down =
Table 2
3.3V
5V
12V
15V
24V
48V
5.8 - 10.52 x 0.4
= 3.98 (KΩ)
0.4
Ω
6.18
5.8
86.45
150
430
1569.6
20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2383
Ω
15
10.52
60.1
94
120
295.527
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page
7 of 10
date
04/2011
DESCRIPTION: half-brick dc-dc converter
PART NUMBER: VHB75W
8. OUTPUT OCP AND SHORT-CIRCUIT PROTECTION
Output overload and short circuit conditional will cause the output voltage to decline or shutdown altogether.
If the case temperature
is not over 100°C, the output recovers automatically when the short or OCP conditions are removed. In the case of slight overloading,
the output voltage may not shut down, but the converter may build up heat over time, causing over-temperature shutdown.
9. OVER-TEMPERATURE PROTECTION
When the case temperature reaches about 100°C, the converter's built-in protection circuit will shut down the output. When the temperature is reduced enough to a safe operating level, the converter will recover to normal operations automatically.
10. OUTPUT OVP
In case the output voltage exceeds the OVP threshold, the converter shuts down.
11. OUTPUT PARALLEL CONNECTIONS
The converter is not designed for load share on the output. One may be inclined to use this circuit to force current sharing by trimming the output voltages for each converter. However, this circuit may not reliably or accurately divide the load current, as the device
characteristics of the converters or the diodes may not be balanced over a range of operating conditions. We generally do not recommend this circuit to increase power output over a single converter. Instead, we recommend this setup for redundancy only, having
one converter as a backup in case of a failure. Make sure the OR-ing diodes can handle the voltage and full load current.
+Vin
-Vin
FIGURE 6. OUTPUT
+Vo
-Vo
PARALLEL CONNECTIONS
+Vin
-Vin
+Vo
-Vo
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page
8 of 10
date
04/2011
DESCRIPTION: half-brick dc-dc converter
PART NUMBER: VHB75W
12. OUTPUT SERIES CONNECTIONS
Two or more converters can be connected in series to obtain a higher output voltage. To prevent output reverse biasing each other in
case of a short, add a Schottky diode on each output in reverse polarity, as shown in the diagram. In the event of a short, the converters will forward-bias the diodes and the output reversal will be limited to one diode drop (about 0.5V) only, so as not to damage
the converters. The forward current will cause each converter to go into short-circuit protection.
For proper diode selection, make
sure that: 1) the diodes voltage rating is higher than each converter output; 2) the rated diode current can carry the short-circuit current; 3) the diodes do not overheat before the short is removed.
+Vin
-Vin
FIGURE 7. OUTPUT
+Vo
-Vo
SERIES CONNECTIONS
+Vin
-Vin
+Vo
-Vo
13. REMOTE OUTPUT ON/OFF CONTROL
The converter output can be enabled or disabled through the On/Off pin. The control logic is shown in this table. A common control
circuit is shown below. The standard version defaults to positive logic. For negative logic, indicate the selection when ordering.
REM
REM (pin 2)
+Vo
SW
SW
High signal here
disable output
-Vin
-Vin (pin 4)
-Vo
FIGURE 8. REMOTE ON/OFF CONTROL
FIGURE 9. REMOTE ON/OFF CONTROL
WITH TRANSISTOR SWITCH
Logic Table
Negative logic
SW Closed (V REM <0.8 V) Output on
SW Open (V REM >2.4 V)
Output off
Positive logic
Output off
Output on
14. ISOLATION
The input and output of the converter are electrically isolated. If needed, an output terminal can be connected to an input terminal,
resulting in the converter non-isolated.
20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2383
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page
9 of 10
date
04/2011
DESCRIPTION: half-brick dc-dc converter
PART NUMBER: VHB75W
15. INPUT FILTERING AND EMI INTERFERENCE
The VHB75W converters have input capacitors that control input current ripple and the associated EMI interference. However, it
has not been tested to a formal standard for conducted emissions. Additional filtering may be needed to ensure compliance to an
EMI standard. Refer to FIGURE 10 for a reference circuit.
V-Infinity offers a line of dc input filter modules designed to help reduce common and differential mode noise. The table below
provides a list of dc-dc converter models within the series and the mating dc input filter.
Series
Mating Filter Module
VHB75W-Q24-SXX
VFM-10A
VHB75W-Q48-SXX
VFM-10A
Notes
FIGURE 10. EMI FILTER FOR VHB75W
L2
C2
+Vin
+Vo
-Vin
CASE -Vo
C3
C4
VHB75W Series
C2
47µF/50V
EMI to meet class A
ESR<0.60
220µF/50V
EMI to meet class B
ESR<0.120
C3
47µF/50V
ESR<0.60
220µF/50V
ESR<0.120
C4
2200pF/2KV
L2
2.5µH
2200pF/2KV
1.5µH
note: The recommended components are a starting point but not guaranteed for meeting these EMI requirements. More or less
filtering may be required for a specific application or to meet other EMI standards, e.g.MIL-STD-461
20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2383
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page
10 of 10
date
04/2011
DESCRIPTION: half-brick dc-dc converter
PART NUMBER: VHB75W
16. OUTPUT FILTERING
The converter has built-in capacitors at the output to control ripple and noise. If desired, additional output capacitance can be
introduced at the input to the powered equipment. Recommended starting point: one 10μF tantalum and one 1μF ceramic capacitor in
parallel at the output.
17. OUTPUT NOISE MEASUREMENT SCHEMATIC
For proper output ripple and noise measurement, connect a 10μF tantalum and a 1μF ceramic capacitor across the output. Set the
scope bandwidth to 20MHz. Probe directly off of one of the capacitors, using a small ground clip to minimize measurement error.
+Vin
+Vo
Ceramic
1.0µF
+S
Trim
+
Resistor
Load
-S
-Vin
-Vo
Solid Tantalum
10µF
To Scope
FIGURE 11. OUTPUT NOISE MEASUREMENT CIRCUIT
20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2383
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