Pr eliminar y
75 Watt HEW Single Series DC/DC Converters
Features
4:1 input voltage range
Small size 2.4”x2.28”x0.55”
Excellent thermal performance with metal baseplate
Volt-seconds clamp and fast over voltage protection
Pulse-by-pulse current limiting, short circuit frequency
foldback, dead short shut down
Over-temperature protection
Auto-softstart
Low noise
Industry-standard pinout
Constant frequency for normal operation
Remote Sense
Description
The 4:1 Input Voltage 75 W single HEW Series of DC/DC
converters provide precisely regulated dc outputs. The output
voltage is fully isolated from the input, allowing the output to
be positive or negative polarity and with various ground
connections. The HEW Series meets the most rigorous
performance standards in an industry standard case size for
data communications and process control applications.
The 4:1 Input Voltage 75 Watt HEW Series includes
remote sensing, output trim, and remote on/off. Threaded-
through holes are provided to allow easy mounting or add a
heat sink for extended temperature use.
Remote ON/OFF
Super energy saving, 2 mA input idle current
Output trim with very low temperature coefficient
Water Washable, wide humidity applications
Good shock & vibration damping
Selection Chart
Model
24S3.20HEW
24S5.15HEW
24S12.6HEW
24S15.5HEW
24S24.3HEW
48S3.20HEW
48S5.15HEW
48S12.6HEW
48S15.5HEW
48S24.3HEW
Input Range
VD C
Min
9
9
9
9
9
18
18
18
18
18
Max
36
36
36
36
36
75
75
75
75
75
I in
ADC
Typ
3.36
3.68
3.63
3.59
3.59
1.66
1.82
1.80
1.78
1.78
V out
VD C
3.3
5
12
15
24
3.3
5
12
15
24
I out
ADC
20
15
6.25
5
3.125
20
15
6.25
5
3.125
A
Default ON/OFF logic is positive.
Add -N to the model number to order negative ON/OFF logic.
2401 Stanwell Drive • Concord, California 94520 • Ph: 925/687-4411 or 800/542-3355 • Fax: 925/687-3333 • www.calex.com • Email: sales@calex.com
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9/23/2004, eco# 041007-1
Pr eliminar y
75 Watt HEW Single Series DC/DC Converters
Output Parameters
24S3.20HEW
48S3.20HEW
24S5.15HEW
48S5.15HEW
24S12.6HEW
48S12.6HEW
24S15.5HEW
48S15.5HEW
24S24.3HEW
48S24.3HEW
Unless otherwise stated, these specifications apply for ambient temperature T
A
=23 ±2°C, nominal input voltage, and rated full load. (1)
Model
Output Voltage
Turn On Overshoot
Temperature Coefficient
Noise (8)
Load Current (4)
Load Transient Overshoot (7)
Load Transient Recovery Time (6)
Load Regulation (5)
Min-Max Load
Line Regulation
Vin = Min-Max
Overvoltage Protection (OVP)
Threshhold
OVP Type - Non-latching
Open Loop Overvoltage Clamp
Output Current Limit
V out=90% of V out-nom
Output Short Circuit Current
V out = 0.25 V
TYP
TYP
MAX
TYP
TYP
TYP
TYP
TYP
TYP
MAX
TYP
MAX
MIN
MAX
TYP
TYP
MAX
Units
VDC
%
%/°C
3.3
0.005
0.01
75
20
20
5
12
0
0.003
0.005
15
24
75
20
15
150
60
6.25
3
200
0.02
0.2
0.01
0.1
115
135
120
140
150
150
60
6.5
250
100
3.125
mV P-P
mV RMS
ADC
%
µSec
%
%
%
%
%
NOTES:
(1)
(2)
(3)
Refer to the CALEX Application Notes for the definition of terms,
measurement circuits, and other information.
Refer to the CALEX Application Notes for information on fusing.
For inrush current, refer to the specifications above.
33 µF capacitor connected to two “Input” pins. Then place
current sensor in series with 12 µH inductor between 33 µF and
the source. The reflected ripple current is measured over a 5 Hz
to 20 MHz bandwidth.(current sensor is located between the
converter input pin and the 12 uH inductor)
Optimum performance is obtained when this power supply is
operated within the minimum to maximum load specifications.
No damage to the module will occur when the output is operated
at less than minimum load, however the output voltage may
contain a low frequency component that may exceed output
noise specifications.
Load regulation is defined as the output voltage change when
changing load current from maximum to minimum.
Load Transient Recovery Time is defined as the time for the
output to settle from a 50 to 75% step load change to a 1% error
band (rise time of step = 2µSec).
Load Transient Overshoot is defined as the peak overshoot
during a transient as defined in the Note 6 above.
Noise is measured per the CALEX Application Notes. Output
noise is measured with a 10µF tantalum capacitor in parallel with
a 0.1 µF ceramic capacitor connected across the output to CMN.
Measurement bandwidth is 0-20 MHz.
(9)
When an external On/Off switch is used, such as open collector
switch, logic high requires the switch to be high-impedance.
Switch leakage currents greater than 10 µA may be sufficient to
trigger the On/Off to the logic-low state.
(10) Most switches would be suitable for logic On/Off control. In case
there is a problem, you can make following estimations and then
leave some margin.
When open collector is used for logic high, “Open Circuit Voltage
at On/Off Pin”, “Output Resistance” and “External Leakage
Current Allowed for Logic High” are used to estimate the high
impedance requirement of open collector.
When switch is used for logic low, “Open Circuit Voltage at On/
Off Pin”, “Output Resistance” and “LOW Logic Level” are used
to estimate the low impedance requirement of switch.
(11) Thermal impedance is tested with the converter mounted vertically
and facing another printed circuit board 1/2 inch away. If
converter is mounted horizontally with no obstructions, thermal
impedance is approximately 8 °C/W.
(12) Water Washability - Calex DC/DC converters are designed to
withstand most solder/wash processes. Careful attention should
be used when assessing the applicability in your specific
manufacturing process. Converters are not hermetically sealed.
(4)
A
(5)
(6)
(7)
(8)
2401 Stanwell Drive • Concord, California 94520 • Ph: 925/687-4411 or 800/542-3355 • Fax: 925/687-3333 • www.calex.com • Email: sales@calex.com
3
9/23/2004, eco# 041007-1
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