CBAMTM HU-28
Features
· All ceramic solution
· High energy density
· User programmable hold-up trip voltage
· Trip status indicator
· Designed for use with Calex DC/DC Converters
· Compact package design (2.40" x 2.28" x 0.50")
· Aluminum substrate technology
· All applicable materials used are a minimum of
UL94V-0 rated. Designed to meet UL60950.
· Five year warranty
· Available with RoHS compliant construction,
simply add "(RoHS)" after the part number:
HU-28 (RoHS)
Description
The HU-28 is a hold-up module designed for use with
Calex DC/DC converters to protect against brown-out
and temporary power loss conditions and provide a
clean, uninterrupted source of power for downstream
circuitry. The HU-28 is built in a compact package with a
user programmable hold-up trip voltage.
Figure 1. Recommended Application
CompuMess Elektronik GmbH · Lise-Meitner-Str. 1 · D-85716 Unterschleißheim
Telefon (089) 32 15 01 - 0 · Telefax (089) 32 15 01 - 11
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1 6/16/08
CBAMTM HU-28
Principles of Operation
The HU-28 has two modes of operation: "stand-by"
and "tripped". During stand-by, the HU-28 charges the
internal hold-up capacitor to 45V and maintains that
voltage. When tripped, the HU-28 stops charging the
Hold-up Time (ms)
hold-up capacitor and connects it to the VOUT pins.
The mode of operation is determined by the value of the
input voltage (+INPUT) in relation to the "trip voltage".
Tripped mode is entered when the input voltage drops
below a preset trip voltage. Stand-by mode is entered
when the input voltage rises 2.1V above the trip voltage.
The trip voltage is set by the user via the VPROG pin.
Power Draw (W)
Figure 3. Hold-up Time as a function of Power Draw
Thermal Considerations
In stand-by mode, the HU-28 does not dissipate much
heat and the baseplate temperature will typically be
5ºC higher than ambient temperature in a still air
environment. When the HU-28 transitions from tripped to
stand-by mode and vice versa, a large amount of power
is dissipated in the HU-28. If frequent transitions are
expected, care should be taken to ensure the baseplate
Figure 2. Internal Block Diagram temperature does not exceed 100ºC.
Caution
Hold-up Time After shutting off power to the HU-28, do not handle the
circuit until the hold-up capacitor is discharged. With
Hold-up time is dened as the maximum time that the
no load on the output, voltages in excess of 45V may
downstream circuitry can be powered solely from the
be present on the VCAP and VOUT pins for a prolonged
hold-up capacitor. In this data sheet, hold-up time is
period of time.
dened as the time when the downstream circuitry
is powered solely from the hold-up capacitor and the
hold-up capacitor is charged to at least 10V. Figure 3
illustrates the maximum hold-up time (ms) that can be
achieved at different levels of power draw. This time
can be increased by adding external capacitance to
the HU-28. Ceramic capacitors are used to store the
hold-up energy. The capacitance of ceramic capacitors
decreases logarithmically with time. Therefore the hold-
up time will decrease slightly over the lifetime of the HU-
28. The capacitors may be reset to their original value by
heating them above the Curie temperature. Contact the
factory for details.
CompuMess Elektronik GmbH · Lise-Meitner-Str. 1 · D-85716 Unterschleißheim
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CBAMTM HU-28
Notes:
Input Parameters (1) All parameters measured at Tc=25ºC, Vin=28VDC,
Input Voltage Range MIN (3) 15.5 unless otherwise noted. Refer to the CALEX Application
TYP 28 VDC Notes for the denition of terms, measurement circuits,
MAX 36 and other information.
(2) Refer to the CALEX Application Notes for information
Input Current, hold-up capacitor charged TYP 25 mARMS
on fusing.
Input Current while charging hold-up MIN 20 (3) The HU-28 does not charge the hold-up capacitor
capacitor MAX 350 mA when the input voltage is below the trip voltage.
Input Overvoltage, 100ms MAX 50 VDC (4) The response time is dened as the time from when
the input voltage drops to the trip voltage to the time
Switching Frequency TYP 310 kHz when the output voltage "VOUT" starts rising.
Reected Ripple TYP 40 mA P-P (5) This capacitance includes all input capacitance on the
downstream circuitry: internal and Co.
Recommended Input Fuse Note (2) (6) Isolation is measured by applying a DC voltage
Output Parameters between pins and baseplate.
(7) The case thermal impedance is dened as the case
Hold-up Cap voltage (pins 6 and 7) MIN 44
temperature rise over ambient per package watt
TYP 45 VDC dissipated.
MAX 46
(8) Thermal impedance is tested with the module mounted
Hold-up Cap Charge Time TYP 330 ms vertically and facing another printed circuit board 1/2
inch away.
Maximum User Capacitance MAX 50,000 µF
(9) Torque fasteners into threaded mounting inserts at 12
Response Time (4) TYP 5 µs in. oz. or less. Greater torque may result in damage to
VCAP to VOUT Voltage Drop MIN 0.6 VDC unit and void the warranty.
(10) Calex CBAMTM modules are designed to withstand
Hold-up Output Power MAX 200 W most solder/wash processes. Careful attention
Hold-up capacitor aging Contact the Factory should be used when assessing the applicability in
your specic manufacturing process. The CBAMTM
VOUT Voltage MIN 9.0 modules are not hermetically sealed.
VDC
MAX 45.5 (11) MTBF is calculated based on MIL-HDBK-217F under
Output Capacitance (5) TC 80ºC MAX 350 the following conditions:
µF Reliability prediction method = Part Stress Analysis
TC 100ºC MAX 170
Baseplate temperature = 40ºC
Control Parameters Environment = Ground, Benign
(12) Available with RoHS and Non-RoHS construction,
Trip Voltage VPROG = 0V MIN 21.4
contact factory for details.
TYP 22 VDC
RoHS Compliance means conformity to EU Directive
MAX 22.5
2002/95/EC of 27 January 2003, on the restriction of
VPROG MIN 17.5 VDC the use of certain hazardous substances in electrical
Open TYP 18 and electronic equipment, lead, cadmium, mercury,
MAX 18.5 hexavalent chromium, polybrominated biphenyls,
VPROG = 5V MIN 13 and polybrominated diphenyl ethers are not present
TYP 13.5 VDC in quantities exceeding the following maximum
MAX 14 concentrations in any homogeneous material, except
for applicable exemptions.
Trip Voltage Hysteresis TYP 2.1 VDC 0.1% (by weight of homogeneous material) lead,
VPROG Voltage MIN 0 mercury, hexavalent chromium, polybrominated
VDC biphenyls, polybrominated diphenyl ethers, or 0.01%
MAX 5
(by weight of homogeneous material) cadmium.
Input Impedance TYP 24 kOhm The RoHS marking is as follows.
Status Pin Voltage MAX 50 VDC
Status Pin Current MAX 2 mA
CompuMess Elektronik GmbH · Lise-Meitner-Str. 1 · D-85716 Unterschleißheim
Telefon (089) 32 15 01 - 0 · Telefax (089) 32 15 01 - 11
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CBAMTM HU-28
Isolation
Baseplate to Input (6) MIN 700 VDC
Enviromental
Baseplate Operating Temp Range MIN -40 ºC
MAX 100
Storage Temperature Range MIN -40 ºC
MAX 120
Case Thermal Impedance (7), (8) TYP 7 ºC/Watt
MTBF MIL-STD-217F (11) Contact the Factory
General
Unit Weight TYP 125 g
Case Dimension 2.40" x 2.28" x 0.50"
Torque on Mounting Inserts (9) MAX 12 in. oz
Pin Diameter Name Mechanical tolerances unless otherwise noted:
X.XX dimensions: ±0.020 inches
1 0.080" +INPUT X.XXX dimensions: ± 0.005 inches
2 0.040" GND
3 0.040" STATUS
4 0.080" VPROG
5 0.080" GND
6 0.040" VCAP
7 0.040" VCAP
8 0.040" VOUT
9 0.080" VOUT
CompuMess Elektronik GmbH · Lise-Meitner-Str. 1 · D-85716 Unterschleißheim
Telefon (089) 32 15 01 - 0 · Telefax (089) 32 15 01 - 11
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4 6/16/08
CBAMTM HU-28
HU-28 Application Section
Hold-up Time Note that this hold-up time can only be achieved after the
hold-up capacitor has been fully charged. Therefore the
Hold-up time, as dened earlier, depends on downstream hold-up time is reduced or non-existent whenever the
circuitry power draw, power loss in the HU-28, the amount hold-up capacitor is not charged to 45V. This condition
of external hold-up capacitance, and the initial voltage of is present immediately after start-up and immediately
the hold-up capacitor. after recovering from a brown-out. Power loss due to
Generally, for a C farad capacitor charged to V volts, the the voltage drop from VCAP to VOUT will slightly reduce
amount of energy available to provide hold-up is: this theoretical hold-up time.
1 2 1 2
E= · C ·V · C·10
2 2
Trip Voltage Set-point
Therefore, a load drawing P watts will be supplied for t
seconds: There are three ways to set the trip voltage for the
HU-28.
t = E = 1 · C · (V2-102)
P 2 P
I. Connect a voltage source (0 to 5V) to VPROG to obtain
Assuming full 45V charge in the hold-up capacitor, any trip voltage between 13.5V and 22V. The trip
constant power draw, and no loss in the HU-28, the voltage may be computed as:
hold-up time can be estimated by:
VTRIP = 21.9 - 1.69VPROG
th = 1 · C · (452-102)
2 P
Alternately it can be estimated from gure A2.
where th is the hold-up time in seconds. The HU-28 has
a 0.85mF internal hold-up capacitor. An external hold-up
capacitor will increase hold-up time as shown in gure
A1. In general, for a given power draw, the HU-28 can
provide a hold-up time th,0 as shown in gure 3. If more
hold-up time is desired, external capacitance Ch (mF)
Trip Voltage (V)
may be added. For a desired hold-up time, th,e, compute
required capacitance as:
t
Ch = 0.85 ( th, -1 )
h,e
0
For example, a 100W load requires 20ms hold-up time.
VPROG (V)
According to gure 3, the HU-28 can only provide 8ms
hold-up time. Therefore 0.85 · (20/8 -1) = 1.28mF of Figure A2. Trip voltage as a function of VPROG
external capacitance is required.
II. For 18V trip voltage, leave VPROG open. Hysteresis
is reduced to 1.6V.
III. External resistor method. This method allows the trip
voltage to be set to any value between 13.5V and 22V,
without using a separate voltage source. However,
Hold-up time (ms)
using this method, the hysteresis is reduced to as
low as 1V, therefore stand-by mode may be entered
whenever the line voltage rises as low as 1V above
the trip voltage.
a. For a trip voltage smaller than 18V, connect a resistor
between VPROG and +INPUT as shown in gure A3.
The trip voltage can be estimated from gure A4.
b. For a trip voltage greater than 18V, connect a resistor
Power Draw (W) between VPROG and GND as shown in gure A5. The
Figure A1. Hold-up time as a function of external trip voltage can be estimated from gure A6.
capacitance (Ch) and power draw
CompuMess Elektronik GmbH · Lise-Meitner-Str. 1 · D-85716 Unterschleißheim
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CBAMTM HU-28
Follow these steps to pick a trip voltage:
1. Decide on the lowest acceptable voltage for the
downstream circuitry.
2. Compute or measure the change in voltage on the
positive input of the downstream circuitry during
the 5µs HU-28 response time. This depends on
downstream circuitry input capacitance (both internal
Figure A3. External resistor method for obtaining a trip and external), power draw, and trip voltage.
voltage smaller than 18V 3. To obtain the trip voltage, add the two values above
and the forward voltage drop of the input diode DI.
Status Pin
Pin 2, STATUS, allows external circuitry to monitor the
state of the HU-28 as shown in the table below. This
Trip Voltage (V)
pin is connected to the open drain of a FET, therefore a
pull-up resistor to the logic high voltage is required for
normal operation.
Status Pin HU-28 Status
logic low Tripped
logic high Stand-by
Resistance (k)
Figure A4. Trip voltage as a function or resistance Figure A7 shows an arrangement where a TTL compatible
connected between VPROG and +INPUT signal is generated at the STATUS pin. VPROG is open,
therefore the trip voltage is 18V. The voltage on +INPUT
is ramped down then up. Figure A8 shows the behavior
of the STATUS pin. Note that the HU-28 returns to stand-
by mode only after +INPUT rises about 2V above the trip
voltage.
Figure A5. External resistor method for obtaining a trip
voltage greater than 18V
Figure A7. STATUS pin congured for TTL operation
Trip Voltage (V)
Resistance (k)
Figure A6. Trip voltage as a function of resistance
connected between VPROG and GND
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CBAMTM HU-28
Figure A10b. Incorrect conguration: Converter current
through HU-28
Hysteresis and Lack of Brown-out
Protection
Figure A8. STATUS pin operation. ch1: +INPUT voltage,
ch2: STATUS voltage Once the HU-28 trips, the hold-up capacitor will not
be recharged until the input voltage rises 2.1V above
the trip voltage. If, after the HU-28 is tripped, the input
voltage recovers but does not rise at least 2.1V over the
Ground Connection trip voltage, the HU-28 will not provide any protection
from any subsequent brown-out.
There are two GND pins (2 and 5) on the HU-28. Avoid Consider the following scenario: The trip voltage is
running current through the module from one pin to the 18V. The line voltage (28V) drops out for 500ms.
other. The correct conguration is shown in gure A9. Uninterrupted power is provided by the HU-28. The
Some incorrect congurations are presented in gures line recovers, but only to 19V. The HU-28 remains in
A10a and A10b. tripped mode, as the line voltage does not rise above
20V. Another 400ms brown-out occurs after which the
line voltage fully recovers to 28V. Since the hold-up
capacitor is only partially charged the HU-28 can not
keep the load running. This is illustrated in gure A11.
The same experiment is repeated after setting VPROG to
3.5V for a trip voltage of 16V. The results are shown in
gure A12.
To avoid this problem, set the trip voltage 2.1V lower
Figure A9. HU-28 properly congured to avoid high than the lowest permissible value for the line voltage.
currents through the module
Figure A10a. Incorrect conguration: Hold-up current
through HU-28
CompuMess Elektronik GmbH · Lise-Meitner-Str. 1 · D-85716 Unterschleißheim
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CBAMTM HU-28
HU-28 Input Capacitance
Ci and Co shown in gure 1 are optional and are not
required for proper operation of the HU-28. Co may
be used if downstream circuitry requires external
capacitance. If the required input capacitance is greater
than the limit set by the HU-28 output capacitance, Ci
may be used in parallel with Co to attain the desired
capacitance. When the HU-28 is used with Calex HEW
series converters, 220µF for Ci and 40µF for Co are
recommended. Depending on operating conditions and
converter model, other values may be required.
Measurements
Figure A11. HU-28 does not provide protection due to
high trip voltage.
Figure A13. Brown-out event
Figure A12. Lower trip voltage allows the HU-28 to
provide protection.
Layout Issues
+INPUT connection.
Connect +INPUT directly to the anode of the input diode,
DI. This will provide the best measurement of the input
voltage.
Stray Inductance on Output.
Care must be taken to reduce stray inductance that may
be present between any external hold-up capacitors, the
HU-28, and the downstream circuitry. When HU-28 trips,
the voltage on VOUT will suffer a step rise as large as
35V. This will be accompanied by a 35A inrush current
into the output capacitance. Inductance present in the
Figure A14. Start of brown-out event in gure A15
path of this current will cause a large voltage spike and/
or ringing on VOUT.
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CBAMTM HU-28
Figure A18. HU-28 input current (ch4) with respect to
Figure A15. End of brown-out event in gure A13 hold-up capacitor voltage (ch1) at +INPUT = 36V
Figure A16. HU-28 input current (ch4) with respect to Figure A19. Typical input current ripple (ch4) while
hold-up capacitor voltage (ch1) at +INPUT = 15.5V hold-up capacitor is charging (ch1)
Figure A17. HU-28 input current (ch4) with respect to Figure A20. Typical input ripple when HU-28 is in stand-by
hold-up capacitor voltage (ch1) at +INPUT = 28V mode
CompuMess Elektronik GmbH · Lise-Meitner-Str. 1 · D-85716 Unterschleißheim
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