1ECO# 060615-3, 061207-3, 070612-5, 121120-2
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
75 WATT LT TRIPLE SERIES
DC/DC CONVERTERS
Features
Small size 2.4” x 2.28” x 0.55”
Excellent thermal performance with metal baseplate
Non-latching over voltage shutdown
Pulse-by-pulse current limiting, short circuit foldback
Over-temperature protection
Auto-softstart
Low noise
Constant frequency for normal operation
2:1 input voltage range
Positive logic primary remote On/Off
Very low temperature coefcient
Water Washable
Trimmable output voltages
Low cost
5 Year Warranty
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Selection Chart
Model
Input Range
VDC Vout
VDC
Iout
ADC*
(All outputs)
Min Max
24T5.3.2LT 18 36 5, 3.3, 2.5 10
24T3.2.1R8LT 18 36 3.3, 2.5 , 1.8 10
24T3.2.1R5LT 18 36 3.3, 2.5 , 1.5 10
The LT Triple Series DC/DC family provides three
independent and precisely regulated low output voltage
converters in one package reducing cost and saving
board space. The LT Series meets rigorous requirements
in an industry standard 1/2 brick package, and is well
suited for telecom and industrial applications.
All three outputs are rated for a maximum of 10 Amps,
thus providing many possible output load combinations
with a total output power of 75 Watts. The remote trim
function on each output can be used to compensate for
voltage drops between the converter and the load at
higher currents.
The LT Series includes a primary remote on/off for power
conservation. The LT package features threaded-through
holes to allow for easy mounting or the addition of a heat
sink for extended temperature operation.
Description
* The output currents are the maximum ratings of each of the outputs.
It is up to the user to keep the total power output at or below the 75 Watt
rating of the package.
** For other output voltages and 48 Volt input models contact the factory.
2ECO# 060615-3, 061207-3, 070612-5, 121120-2
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
75 WATT LT TRIPLE SERIES
DC/DC CONVERTERS
Input Parameters
Model 24T5.3.2LT 24T3.2.1R8LT
24T3.2.1R5LT
Units
Voltage Range
MIN
TYP
MAX
18
24
36
VDC
Input Overvoltage (100 ms) MAX 50 VDC
Input Ripple Rejection (120Hz) TYP 50 dB
Undervoltage Lockout Yes
Input Reverse Voltage Protection Yes
Input Current No Load
100% Load
TYP
TYP
12
3.6
mA
A
Inrush Current MAX 0.5 A2s
Reected Ripple, 12µH
Source Impedance (4) TYP 20 mA p-p
Efciency TYP 81 77 %
Switching Frequency TYP 360 kHz
Recommended Fuse (3) AMPS
Unless otherwise stated, these specications apply for baseplate temperature Tb=23±2ºC, nominal input voltage, and rated full load. (1) (2)
Notes:
(1) Refer to the CALEX Application Notes for the denition of terms,
measurement circuits, and other information.
(2) Full Load is dened as the main output operating at 10 Amps.
The Auxiliary outputs are equally loaded to bring output power to
75 Watts, or loaded to 10 Amps maximum on each.
(3) This unit is not fused and needs to be fused by the user. Refer
to the CALEX Application Notes for information on fusing. For
inrush current, refer to the specications above.
(4) Place a 33 µF capacitor between the two “Input” pins. Then
place the current sensor in series with 12 µH inductor between
the capacitor and the source. The reected ripple current is
measured over a 5 Hz to 20 MHz bandwidth. Noise should be
minimized in the measurement.
(5) Noise is measured per the CALEX Application Notes. Output
noise is measured with a 10 µF tantalum capacitor in parallel
with a 0.1 µF ceramic capacitor connected across the output to
CMN. Measurement bandwidth is 0-20 MHz.
(6) Optimum performance is obtained when this power supply is
operated within the minimum to maximum load specications.
No damage to the module will occur when the output is operated
at less than minimum load, but the output voltage may contain
a low frequency component that may exceed output noise
specications. At no load the converter’s Vo1 output voltage
may fall out of regulation, typically rising to the OVP limit. A load
current of between 0.5% to 1% of maximum rated load on any of
the outputs will usually sufce to bring Vo1 within regulation.
(7) Load Transient Recovery Time is dened as the time for the
output to settle from a 50 to 75% or 25% step load change to a
1% error band of output voltage (rise time of step = 2µs).
(8) Load Transient Overshoot is dened as the peak overshoot
during a transient as dened in the Note 7 above.
(9) Load Regulation is dened as the output voltage change when
changing load current from maximum to minimum. The voltage
is measured at the output pin.
(10) Most switches would be suitable for logic ON/OFF control. In case
there is a problem, you can make the 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 the 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 obstruction, thermal impedance is
approximately 7°C/W.
(12) Minimum load is dened as 10% of maximum load. Calex Mfg.
Co. Inc. does not guarantee performance for loads less than the
minimum. Loads less than the minimum shall not damage the
unit.
(13) 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 10µA may be sufcient to
trigger the ON/OFF to the logic-low state.
(14) 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 specic
manufacturing process. Converters are not hermetically sealed.
(15) Torque fasteners into threaded mounting inserts at 12 in.oz. or
less. Greater torque may result in damage to unit and void the
warranty.
3ECO# 060615-3, 061207-3, 070612-5, 121120-2
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
75 WATT LT TRIPLE SERIES
DC/DC CONVERTERS
Output Parameters (VO1)
Model 24T5.3.2LT 24T3.2.1R8LT
24T3.2.1R5LT
Units
Output Voltage 5 3.3 VDC
Output Voltage
Setpoint Accuracy MAX ±1 %
Turn On Overshoot TYP 0 %
Temperature Coefcient TYP
MAX
0.003
0.01 %/ºC
Noise & Ripple (5) TYP
MAX
50
100
33
66 mV p-p
Load Current (6) (12) MIN
MAX
1.0
10.0 A
Load Transient Overshoot (8) TYP 4 %
Load Transient Recovery Time (7) TYP 100 µSec
Load Regulation (9)
Min-Max Load
TYP
MAX
0.5
1%
Line Regulation
Vin = Min-Max
TYP
MAX
0.1
0.5 %
Overvoltage Protection (OVP)
Threshhold
OVP Type - Non-latching
Open Loop Overvoltage Clamp
TYP 130 %
Output Current Limit
Vout = 90% of Vout-nom TYP 120 %
Output Short Circuit Current
Vout = 0.25V TYP 175 %
Output Parameters (VO2, VO3)
(VO2) (VO3)
Model 24T5.3.2LT 24T3.2.1R8LT
24T3.2.1R5LT 24T5.3.2LT 24T3.2.1R8LT 24T3.2.1R5LT Units
Output Voltage 3.3 2.5 2.5 1.8 1.5 VDC
Output Voltage
Setpoint Accuracy MAX ±3.0 %
Turn On Overshoot TYP 0 %
Temperature Coefcient TYP
MAX
0.02
0.05 %/ºC
Noise & Ripple (5) TYP
TYP
33
66
25
50
25
50
18
36
15
30 mV p-p
Load Current (6) MIN
MAX
0.2
10.0 A
Load Transient Overshoot (8) TYP 4 %
Load Regulation (9)
Min-Max Load
TYP
MAX
0.5
1.6 %
Line Regulation
Vin = Min-Max
TYP
MAX
0.5
1%
Unless otherwise stated, these specications apply for baseplate temperature Tb=23±2ºC, nominal input voltage, and rated full load. (1) (2)
4ECO# 060615-3, 061207-3, 070612-5, 121120-2
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
75 WATT LT TRIPLE SERIES
DC/DC CONVERTERS
General Specications
All Models Units
Primary Remote ON/OFF Function
HIGH Logic Level
for ON MIN 3.0 VDC
External Leakage Current
Allowed for Logic High (13) MAX 10 µA
Input Diode Protection
Voltage MAX 50 VDC
LOW Logic Level or
Tie ON/OFF Pin to -INPUT MAX 1.0 VDC
Sinking Current for Primary
Logic Low MAX 500 µA
Open Circuit Voltage at
Primary ON/OFF Pin (10) TYP 2.3 VDC
Output Resistance (10) TYP 3 k Ω
Idle Current
(Module is OFF) TYP 2 mADC
Turn-on Time to 1% error TYP 20 mSec
Remote ON/OFF Logic HIGH - Module ON
LOW - Module OFF
Output Voltage Trim
Trim Range MIN
MAX
-5
+5 % of Vout
Input Resistance TYP 10 kΩ
Open Circuit Voltage TYP 2.5 V
Trim Limit
Maximum Output Voltage MAX 105 % of Vout
Isolation
Input to Output Isolation
10µA Leakage MAX 700 VDC
Input to Output Resistance MIN 10 MΩ
Input to Output
Capacitance TYP 1800 pF
Environmental
Calculated MTBF, Bellcore
Method 1, Case 1 >1,000,000 Hr
Baseplate Operating
Temperature Range
MIN
MAX
-40
100 ºC
Storage Temperature MIN
MAX
-40
120 ºC
Thermal Impedance (11) TYP 7 ºC/W
General
Unit Weight TYP 4/114 oz/g
Chassis Mounting Kit MS25
Case Dimension 2.4” x 2.28” x 0.55”
Agency Approvals Designed to meet UL60950
Pin Function Pin Function
1 CASE 8 - V1
2 - INPUT 9 V1 TRIM
3 +INPUT 10 + V1
4 ON/OFF 11 +V2 TRIM
5 - V3 12 + V2
6 +V3 13 - V2
7 V3 TRIM
TOLERANCE: ALL DIMENSIONS ARE TYPICAL IN
INCHES UNLESS OTHERWISE NOTED:
X.XX ±0.020
X.XXX ±0.005