FBA48T25280-PCBM-G - Power-One

FBA48T25280 DC-DC Converter

36-75 VDC Input; 28VDC @ 25A Output

Preliminary Data Sheet

Applications

• RF Power Amplifiers

• Wireless communications

Benefits

• High efficiency

• Low cost

• Integrated metal baseplate design

• Higher power output at elevated temperatures and

low airflow

Features

• RoHS lead-free solder and lead-solder-exempted

products are available

• 28V regulated output at 700W

• Efficiency up to 92%

• Fixed-frequency operation

• Start-up into pre-biased load

• No minimum load required

• Fully protected: UVLO, OCP, OTP, and OVP

• Current share

• Output Good signal

• Auxiliary Output of 7 to 9V at up to 20 mA

• Output voltage trim range: +15%/−40% with

industry-standard trim equations

• Remote differential output voltage sense

• Isolated two-pin ON/OFF

• On-board input differential LC-filter

• Industry-standard fullbrick size and pinout

• Low height of 0.50” (12.7mm)

• Wide operating temperature range from -40 to 100°C

• High reliability: MTBF = TBD million hours

• UL60950 recognized in US and Canada and

DEMKO certified per IEC/EN60950 (pending)

• All materials meet UL94, V-0 flammability rating

Description

The new high performance 700W FBA48T25280 DC-DC converter provides a high efficiency single 28V output in

the fullbrick package. Specifically designed for operation in wireless systems that have limited airflow and

increased ambient temperatures, the FBA48T25280 converter utilizes the same pinout and functionality as the

industry-standard power amplifier bricks.

Operating from a 36-75V input, the FBA48T25280 converter provides a full regulated 28V output voltage that can

be trimmed from –40% to +15% of the nominal output voltage, thus providing outstanding design flexibility. The

open frame module is constructed with a dual board approach using the metal baseplate and discrete magnetics.

The standard feature set includes remote ON/OFF, differential output voltage sensing, input undervoltage lockout,

overtemperature, output overvoltage and overcurrent protections, current sharing, auxiliary voltage output, and the

Output Good signal.

With standard pinout and trim equations, the FBA48T25280 converter is a perfect solution for existing and new

designs. Inclusion of this converter in a design can result in significant power and cost savings. The designer can

expect reliability improvement over other available converters because of the FBA48T25280’s optimized thermal

efficiency.

ZD-02015 Rev 1.3 www.power-one.com Page 1 of 10

FBA48T25280 DC-DC Converter

36-75 VDC Input; 28VDC @ 25A Output

Preliminary Data Sheet

Electrical Specifications

Conditions: TA = 25 ºC, Vin = 48 VDC, Cin=2x220µF, Cout=220µF unless otherwise specified.

Parameter Notes Min Typ Max Units

Absolute Maximum Ratings

Input Voltage Continuous 0 75 VDC

Input Voltage Transient 100 ms 100 VDC

Operating Ambient Temperature Limited by baseplate temperature -40 85 °C

Operating Baseplate Temperature -40 100 °C

Storage Temperature -55 125 °C

Isolation Characteristics

Input to Output Isolation 1500 VDC

Isolation Capacitance 2600 pF

Isolation Resistance 10 MΩ

Input to Baseplate Isolation 1500 VDC

Output to Baseplate Isolation 500 VDC

Feature Characteristics

Switching Frequency 300 kHz

Output Voltage Trim Range1Industry-standard equations -40 +15 %

Remote Sense Compensation1Percent of VOUT(NOM) +10 %

Output Overvoltage Protection Latching 120 128 135 %

Overtemperature Protection (baseplate) Non-latching 120 125 130 °C

Overtemperature Protection Hysteresis 10 °C

ON/OFF Control Controlled by current between ON/OFF+ and ON/OFF- pins

Converter OFF (current is low) -10 0.1 mADC

Converter ON (current is high) 1 5 mADC

Auxiliary Output Voltage 7 9 VDC

Auxiliary Output Current No protected from overcurrent 20 mADC

Output Good Signal (open collector) Output is in regulation – Low, Output is out of regulation - High

Output Good Current Sink 5 mADC

Output Good External Pull-up Voltage 35 VDC

Current Share Accuracy Two units connected in parallel ±10%

Parallel Pin Voltage 156 mV/A

Additional Notes:

1 Vout can be increased up to 10% via the sense leads or 15% via the trim function. However, the total output voltage trim from all sources

should not exceed 15% of VOUT(NOM).

ZD-02015 Rev 1.3 www.power-one.com Page 2 of 10

FBA48T25280 DC-DC Converter

36-75 VDC Input; 28VDC @ 25A Output

Preliminary Data Sheet

Electrical Specifications (continued)

Conditions: TA = 25 ºC, Vin = 48 VDC, Cin=2x220µF, Cout=220µF unless otherwise specified..

Parameter Notes Min Typ Max Units

ut Characteristics

Operating Input Voltage Range 36 48 75 VDC

Input Undervoltage Lockout

Turn-on Threshold 33 36 VDC

Turn-off Threshold 31.5 34.5 VDC

UVLO Hysteresis 1.5 VDC

Maximum Input Current Full Load at 36VDC In

25 ADC

Input Standby Current Vin = 48V, converter disabled 25 mA

Input No Load Current (0A load on the output) Vin = 48V, converter enabled 30 mA

Input Reflected-Ripple Current, icVin = 48V, 25 MHz bandwidth

(Figure 13)

mAPK-PK

Input Ripple Current, isVin = 48V, 25 MHz bandwidth

(Figure 13)

2000

500

mAPK-PK

Input Voltage Ripple Rejection 120 Hz TBD dB

Out

ut Characteristics

External Load Capacitance Plus full load (resistive) 220 10,000 µF

Turn-On Time from Vin Time from UVLO to Vo=90%VOUT(NOM) 30 ms

Turn-On Time from ON/OFF Time from Enable to Vo=90%VOUT(NOM) 15 ms

Output Current Range 0 25 ADC

Current Limit Inception Non-latching 27.5 30 33 ADC

Peak Short-Circuit Current Non-latching, Short = 10 mΩ

65 A

RMS Short-Circuit Current Non-latching

35 Arms

Output Voltage Set Point (no load) 27.72 28.28 VDC

Output Regulation

Over Line

±28 ±56 mV

Over Load ±28 ±56 mV

Over Temperature 200 DPPM

Output Voltage Range Over line, load and temperature 27.25 28.50 VDC

Output Ripple and Noise – 25 MHz bandwidth Full load + 10µF tantalum + 1µF ceramic

+220uF electrolytic 190 280 mVPK-PK

namic Res

onse

Load Change 50%-75%-50% of Iout Max,

di/dt = 0.1 A/µs

450 mV

di/dt = 1A/µs Co =10,000µF

450 mV

Settling Time to 1% of Vout

500 µs

Mechanical

Weight TBD g

Operating Humidity RH (non-condensing) 95 %

Storage Humidity RH (non-condensing) 95 %

Vibration (Sinusoidal) GR-63-CORE, Section 5.4.2

Shock Half Sinewave, 3-axis 50 g

Reliability

MTBF Telcordia SR-332, Method I Case 1

50% electrical stress, 40°C ambient TBD MHrs

ZD-02015 Rev 1.3 www.power-one.com Page 3 of 10

FBA48T25280 DC-DC Converter

36-75 VDC Input; 28VDC @ 25A Output

Preliminary Data Sheet

Operations

Input and Output Impedance

These power converters have been designed to be

stable with a minimum external output capacitor of

220µF when used in low inductance input and output

circuits. If the ambient temperature is lower than

-20°C, then use 4 x 220uF to reduce ESR. Nichicon

UPW1H221MPD or equivalent is recommended.

In many applications, the inductance associated with

the distribution from the power source to the input of

the converter can affect the stability of the converter.

It is recommended that 2 x 220µF with a voltage

rating of 100VDC be used on the input of the

FBA48T25280.

In applications where the user has to use decoupling

capacitance at the load, the power converter will

exhibit stable operation with the external load

capacitance up to 10,000 µF.

ON/OFF Control (Pins 1 and 2)

The ON/OFF pins are used to turn the power

converter on or off remotely via a system signal. The

on/off control is a current driven control. It is isolated

from both the primary and the secondary by

1500VDC. The ON/OFF control turns the converter

on when 1 to 5 mA of current flows from the

ON/OFF+ pin to the ON/OFF- pin. The converter is

off when no current or a small reverse current flows

between the pins. Maximum reverse voltage shall

not exceed 6VDC.

The ON/OFF control current can be generated from

the primary or from the secondary as shown in the

application schematics in Figure 1 and Figure 2.

Vin +

Vin -

On/Off -

On/Off +

Figure 1. ON/OFF Control Using Vin

Figure 2. ON/OFF Control Using Auxiliary Voltage

Remote Sense (Pins 16 and 17)

The remote sense feature of the converter

compensates for voltage drops occurring between

the output pins of the converter and the load. The

SENSE(-) (Pin 16) and SENSE(+) (Pin 17) pins

should be connected at the load or at the point

where regulation is required.

Figure 3. Remote sense circuit configuration.

CAUTION

If remote sensing is not utilized, the SENSE(-) pin must be

connected to the Vout(-) pin, and the SENSE(+) pin must be

connected to the Vout(+) pin to ensure the converter will

regulate at the specified output voltage. If these connections

are not made, the converter will deliver an output voltage that

is higher than the specified data sheet value.

Because the sense leads carry minimal current,

large traces on the end-user board are not required.

However, sense traces should be run side by side

and located close to a ground plane to minimize

system noise and ensure optimum performance.

The converter’s output overvoltage protection (OVP)

senses the voltage across VOUT+ and VOUT-, and

not across the sense lines, so the resistance (and

resulting voltage drop) between the output pins of

the converter and the load should be minimized to

prevent unwanted triggering of the OVP.

When utilizing the remote sense feature, care must

be taken not to exceed the maximum allowable

output power capability of the converter, which is

equal to the product of the nominal output voltage

Rload

Vin

Vin (+)

Vin (-)

VOUT+

VOUT-

TRIM

SENSE (+)

SENSE (-)

FBA48T25280

ZD-02015 Rev 1.3 www.power-one.com Page 4 of 10

FBA48T25280 DC-DC Converter

36-75 VDC Input; 28VDC @ 25A Output

Preliminary Data Sheet

and the allowable output current for the given

conditions.

When using remote sense, the output voltage at the

Output Voltage Adjust /TRIM (Pin 15)

5% or down

ming is not

he output voltage, refer to Figure 4. A

converter can be increased by as much as 10%

above the nominal rating in order to maintain the

required voltage across the load. Therefore, the

designer must, if necessary, decrease the maximum

current (originally obtained from the derating curves)

by the same percentage to ensure the converter’s

actual output power remains at or below the

maximum allowable output power.

The output voltage can be adjusted up 1

40%, relative to the rated output voltage by the

addition of an externally connected resistor. Trim up

to 15% is guaranteed only at Vin ≥ 40V.

The TRIM pin should be left open if trim

being used.

To increase t

trim resistor, RT-INCR, should be connected between

the TRIM pin and SENSE+ pin, with a value of:

1.225∆

22.51∆)V(100

RNOMO

INCRT −

−+

=−

−,[kΩ]

where,

Required value of trim-up resistor kΩ]

=−INCRTR

=−NOMOVNominal value of output voltage [V]

100X

)V(V

∆

NOM- O

NOM-OREQ-O −

= [%]

Desired (trimmed) output voltage [V].

When trim ceed

=−REQOV

ming up, care must be taken not to ex

the converter‘s maximum allowable output power.

See the previous section for a complete discussion

of this requirement.

Figure 4. Configuration for increasing output voltage.

To decrease the output voltage (Figure 5), a trim

resistor RT-DECR should be connected between the

TRIM pin and the SENSE- pin, with a value of:

|∆|

100

RDECRT −=−,[kΩ]

where,

=−DECRTRRequired value of trim-down resistor [kΩ]

and

∆

is defined above.

Figure 5. Configuration for decreasing output voltage.

Trimming/sensing beyond 115% of the rated output

voltage is not an acceptable design practice, as this

condition could cause unwanted triggering of the

output overvoltage protection (OVP) circuit. The

designer should ensure that the difference between

the voltages across the converter’s output pins and its

sense pins does not exceed 15% of VOUT(NOM), or:

X NOM-O SENSESENSEOUTOUT 15%V)](V)([V)](V)([V

≤

−−+

−

[V]

This equation is applicable for any condition of output

sensing and/or output trim.

Parallel Applications

The FBA48T25280 features the active current share

circuit to ensure that the two converters connected in

parallel will share current within ±10% of the total

output current.

Rload

Vin

Vin (+)

Vin (-)

VOUT+

VOUT-

TRIM

SENSE (+)

SENSE (-)

RT-INCR

FBA48T25280

Rload

Vin

Vin (+)

Vin (-)

VOUT+

VOUT-

TRIM

SENSE (+)

SENSE (-)

RT-DECR

FBA48T25280

ZD-02015 Rev 1.3 www.power-one.com Page 5 of 10

FBA48T25280 DC-DC Converter

36-75 VDC Input; 28VDC @ 25A Output

Preliminary Data Sheet

Auxiliary Voltage Output (Pin 12)

The FBA48T25280 has the auxiliary voltage output

voltage connected to pin 12. The voltage on this pin

is not precisely regulated and will vary from 7V to 9V

depending on line and load conditions. This output

is not internally protected and shorting this pin to

ground or to any of the other converter terminals

may cause permanent damage to the converter.

Output Voltage Good signal (IOG) (Pin13)

The signal on pin 13 is active low (open collector).

Whenever the output voltage is out of regulation the

pin is in the high impedance state. The IOG pin can

sink the maximum of 5mADC and it can be externally

pulled up to the maximum of 35VDC.

Protection Features

Input Undervoltage Lockout

Input undervoltage lockout is standard with this

converter. The converter will shut down when the

input voltage drops below a pre-determined voltage.

The input voltage must be typically 34 V for the

converter to turn on. Once the converter has been

turned on, it will shut off when the input voltage

drops typically below 32 V. This feature is beneficial

in preventing deep discharging of batteries used in

telecom applications.

Output Overcurrent Protection (OCP)

The converter is protected against overcurrent or

short circuit conditions. Upon sensing an overcurrent

condition, the converter will switch to constant

current operation and thereby begin to reduce its

output voltage.

When the output voltage drops below 10% of the

nominal value of output voltage, the converter will

shut down.

Once the converter has shut down, it will attempt to

restart nominally every 20 ms with a typical 20% duty

cycle. The attempted restart will continue indefinitely

until the overload or short circuit condition is

removed or the output voltage rises above 90% of its

nominal value.

Once the output current is brought back into its

specified range, the converter automatically exits the

hiccup mode and continues normal operation.

Output Overvoltage Protection (OVP)

The converter will shut down if the output voltage

across VOUT+ and VOUT- exceeds the threshold of

the OVP circuitry. The OVP circuitry contains its own

reference, independent of the output voltage

regulation loop. Once the converter has shut down it

will latch off. The latch can be reset by toggling the

ON/OFF inputs or by recycling the input voltage..

Overtemperature Protection (OTP)

The converter will shut down under an

overtemperature condition to protect itself from

overheating caused by operation outside the thermal

derating curves, or operation in abnormal conditions

such as system fan failure. Ince the converter has

shut down, it will automatically restart after it has

cooled to a safe operating temperature.

Safety Requirements

The converters meet North American and

International safety regulatory requirements per

UL60950 and EN60950. Basic Insulation is provided

between input and output.

The converters have no internal fuse. If required, the

external fuse needs to be provided to protect the

converter from catastrophic failure. Refer to the

“Input Fuse Selection for DC/DC converters”

application note on www.power-one-com for proper

selection of the input fuse. Both input traces and the

chassis ground trace (if applicable) must be capable

of conducting a current of 1.5 times the value of the

fuse without opening. The fuse must not be placed

in the grounded input line.

Abnormal and component failure tests were

conducted with the input protected by a 30A fuse. If

a fuse rated greater than 30A is used, additional

testing may be required. To protect a group of

converters with a single fuse, the rating can be

increased from the recommended value above.

Electromagnetic Compatibility (EMC)

EMC requirements must be met at the end-product

system level, as no specific standards dedicated to

EMC characteristics of board mounted component

dc-dc converters exist. However, Power-One tests its

converters to several system level standards,

primary of which is the more stringent EN55022,

Information technology equipment - Radio

disturbance characteristics-Limits and methods of

measurement.

An effective internal LC differential filter significantly

reduces input reflected ripple current, and improves

EMC.

With the addition of a simple external filter, the

FBA48T25280 converter passes the requirements of

Class A conducted emissions per EN55022 and FCC

ZD-02015 Rev 1.3 www.power-one.com Page 6 of 10

FBA48T25280 DC-DC Converter

36-75 VDC Input; 28VDC @ 25A Output

Preliminary Data Sheet

requirements. Refer to Figure 6 for the

recommended configuration of the input filter.

Figure 6. Input Filter Configuration Required to Meet CISPR 22

Class A for Conducted Emissions.

Startup Information

Scenario #1: Initial Startup From Bulk Supply

ON/OFF function enabled, converter started via application

of VIN. See Figure E.

Time Comments

t0ON/OFF pin is ON; system front-end power is

toggled on, VIN to converter begins to rise.

t1VIN crosses undervoltage Lockout protection

circuit threshold; converter enabled.

t2Converter begins to respond to turn-on

command (converter turn-on delay).

t3Converter VOUT reaches 90% of nominal value.

For this example, the total converter startup time (t3- t1) is

typically 30 ms.

Scenario #2: Initial Startup Using ON/OFF Pin

With VIN previously powered, converter started via

ON/OFF pin. See Figure F.

Time Comments

t0VINPUT at nominal value.

t1Arbitrary time when ON/OFF pin is enabled

(converter enabled).

t2End of converter turn-on delay.

t3Converter VOUT reaches 90% of nominal value.

For this example, the total converter startup time (t3- t1) is

typically 15 ms.

Figure 7. Startup scenario #1.

Figure 8. Startup scenario #2.

ON/OFF

STATE

VOUT

t0t

1t 2t

OFF

VIN

ON/OFF

STATE

VOUT

t0t1t2t3

OFF

ZD-02015 Rev 1.3 www.power-one.com Page 7 of 10

FBA48T25280 DC-DC Converter

36-75 VDC Input; 28VDC @ 25A Output

Preliminary Data Sheet

Characterization

General Information

The converter has been characterized for many

operational aspects, to include thermal derating

(maximum load current as a function of baseplate

temperature), efficiency, startup and shutdown

parameters, output ripple and noise, transient

response to load step-change, overload, and short

circuit.

The following pages contain specific plots or

waveforms associated with the converter. Additional

comments for specific data are provided below.

Test Conditions

All thermal data presented was taken with the

converter mounted to a 6”x12”x1” finned heatsink.

The FBA is designed to operate in an enclosed

environment with the dissipated power being

extracted though the baseplate into the heatsink.

Thermocouples were used to ensure that the internal

components were operating with in their SOA with

the baseplate at 100°C. Refer to Figure 9 for the

optimum thermocouple location.

Thermal Derating

For each set of conditions, the maximum load

current was defined as the lowest of:

(i) The output current at which the base plate

temperature does not exceed a maximum specified

temperature of 100°C as indicated by thermocouple

measure, or

(ii) The nominal rating of the converter.

Temperature at the thermocouple location shown in

Figure 9 should not exceed 100°C in order to operate

inside the derating curves.

Figure 9. Location of the thermocouple for thermal testing.

The derating curve showing available output power as

a function of the baseplate temperature is shown in

Figure 12.

Efficiency

Figure 10 shows the efficiency vs. load current plot for

ambient temperature of 25°C and input voltages of

36V, 48V, 60V, and 75 V.

Power Dissipation

Figure 11 shows the power dissipation vs. load current

plot for Ta = 25°C and input voltages of 36V, 48V,

60V, and 75V.

Vin

On/Of

+Vout

-Vout

+Vout

2.30"

1.2"

ZD-02015 Rev 1.3 www.power-one.com Page 8 of 10

FBA48T25280 DC-DC Converter

36-75 VDC Input; 28VDC @ 25A Output

Preliminary Data Sheet

Characterization Data

Efficiency Curves

86%

87%

88%

89%

90%

91%

92%

51015202

Load Current, A

Efficiency

36V

48V

60V

75V

Figure 12. Available Power Vs. Baseplate Temperature

Test Setup

Figure 10. Efficiency vs. load current and input voltage for

FBA48T25280 converter at Ta=25°C.

5 1015202

Load Current, A

Power Dissipation, W

36V

48V

60V

75V

Figure 13. Test setup for measuring input reflected ripple

currents, ic and is.

Figure 11. Power dissipation vs. load current and input

voltage for FBA48T25280 converter at Ta = 25°C.

ZD-02015 Rev 1.3 www.power-one.com Page 9 of 10

FBA48T25280 DC-DC Converter

36-75 VDC Input; 28VDC @ 25A Output

Preliminary Data Sheet

Physical Information

Pad/Pin # Function

1 ON/OFF+

2 ON/OFF-

3 +VIN

4 -VIN

5 -VOUT

6 -VOUT

7 -VOUT

8 +VOUT

9 +VOUT

10 +VOUT

11 Not used

12 AUX

13 IOG

14 Parallel

15 TRIM

16 -SENSE

17 +SENSE

FBA48T Platform Notes

• All dimensions are in inches [mm]

• Pins 1-2 and 12-17 are Ø 0.040”

[1.02] without a shoulder

• Pins 3-10 are Ø 0.080” [2.04]

without a shoulder

• Pin Material: Brass Alloy 360

• Pin Finish: Tin over Nickel

Tolerances: [Unless otherwise indicated]

x.xxx in. +/- .010 [x.xx mm +/- 0.25]

x.xx in. +/- .020 [x.x mm +/- 0.5]

Converter Part Numbering/Ordering Information

Product

Series

Input

Voltage

Mounting

Scheme

Rated

Current

Output

Voltage ON/OF

F Logic

Maximum

Height [HT]

Pin Length

[PL] Special Features RoHS

FBA 48 T 25 280 - P C A P G

FullBrick

Format 36-75 V

T ⇒

Through-

hole

25 ⇒

25ADC

280 ⇒

28V P ⇒

Positive C ⇒ 0.52”

Through

hole

A ⇒ 0.188”

B ⇒ 0.145”

P ⇒ Parallellable

Q ⇒ Parallellable

with M3 threaded

standoffs

N ⇒ Not

parallellable

M ⇒ Not

parallellable with

M3 threaded

standoffs

No Suffix ⇒

RoHS

lead-solder-

exemption

compliant

G ⇒ RoHS

compliant for

all six

substances

The example above describes P/N FBA48T25280-PCAPG: 36-75 V input, through-hole, 25A @ 28V output, positive ON/OFF logic,

maximum height of 0.52”, 0.188” pins, parallelable with non-threaded standoffs, and RoHS compliant for all 6 substances.

Notes:

1. NUCLEAR AND MEDICAL APPLICATIONS - Power-One products are not designed, intended for use in, or authorized for use as critical

components in life support systems, equipment used in hazardous environments, or nuclear control systems without the express written

consent of the respective divisional president of Power-One, Inc.

2. TECHNICAL REVISIONS - The appearance of products, including safety agency certifications pictured on labels, may change depending

on the date manufactured. Specifications are subject to change without notice.

ZD-02015 Rev 1.3 www.power-one.com Page 10 of 10