48S12.1250TC - Calex Electronics Limited

15 Watt TC Single Series DC/DC Converters

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

1eco# 041007-1

+ INPUT 3

-INPUT

ON/OFF

+ OUTPUT

CMN

TRIM

SHIELDED

ISOLATION TRANSFORMER

LOW TC

BANDGAP REFERENCE

ISOLATED

FEEDBACK

CURRENT

MODE

PWM

FIVE-SIDED SHIELDED COPPER CASE

Features

-40° to +90°C Case Operating

Range Standard

Dual Stage Output Filter for Low Noise Operation

Very Low OFF Current, 1 mA Typically

Water Washable Design

Five Year Warranty

Description

These single output DC/DC converters are designed to provide

a wide range of PCB mount power solutions. The extra wide

3:1 input voltage range covers the common American and

European telecom standards along with 24 volt industrial

control applications.

For flexibility, a trim pin is included to adjust the output

voltage. Use it to compensate for voltage drops in your

system’s wiring or to achieve non standard voltages. Use the

remote ON/OFF function to maximize battery life.

The TC Single Series continues the CALEX tradition of

reliable design by including transient overvoltage suppressor

diode protection at the input and output terminals. Also

provided as standard are overcurrent protection circuits.

These features assure zero failure rate operation when using

the TC Single Series.

15 Watt TC Single Series Block Diagram

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15 Watt TC Single Series DC/DC Converters

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

2eco# 041007-1

NOTES

*All Parameters measured at Tc=25°C, nominal input voltage

and full rated load unless otherwise noted. Refer to the

CALEX Application Notes for the definition of terms,

measurement circuits and other information.

(1) See our application note for picking the correct fuse size.

(2) Noise is measured per CALEX Application Notes. Measurement

bandwidth is 0-20 MHz. RMS noise is measured over a 0.01-1

MHz bandwidth. To simulate standard PCB decoupling practices,

output noise is measured with a 0.1µF, ceramic capacitor

located 1 inch away from the converter.

(3) Minimum load required for rated regulation only. Dynamic

response may degrade if run at less than 25% full load.

(4) Short term stability is specified after a 30 minute warm-up at full

load, and with constant line, load and ambient conditions.

(5) The transient response is specified as the time required to settle

from a 50 to 75% step load change (rise time of step = 2µSec)

to a 1% error band.

(6) Dynamic response is the peak overshoot voltage during the

transient response time defined in note 5.

(7) The input ripple rejection is specified for DC to 120Hz ripple with

a modulation amplitude of 1% Vin.

(8) The ON/OFF pin is Open Collector TTL, CMOS, and relay

compatible. The input to this pin is referenced to Pin 2 (-Input)

and is protected to +75VDC.

(9) Case is tied to Pin 3, +Input.

(10) The case thermal impedance is specified as the case temperature

rise over ambient per package watt dissipated.

(11) Specifications subject to change without notice.

(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.

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15 Watt TC Single Series DC/DC Converters

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

3eco# 041007-1

SIZE TRACES FOR 1 AMP DC MAXIMUM

FUSE

TO INPUT

SOURCE LOAD

SIZE TRACES

APPROPRIATELY FOR

LOAD REQUIREMENTS

PINS 1 AND 6 MAY BE LEFT

FLOATING IF NOT USED

+ INPUT

- INPUT

ON/OFF

+ OUTPUT

CMN

TRIM

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FIGURE 1.

Recommended application circuit for TC Single Series

Mechanical tolerances unless otherwise noted:

X.XX dimensions: ±0.020 inches

X.XXX dimensions: ±0.005 inches

Seal around terminals is not hermetic. Do not immerse units in any

liquid.

15 Watt TC Single Typical Application

Figure 1 shows the recommended connections for the 15 Watt

TC Singles. Capacitor C1 is required for proper operation (see

below). The trim and ON/OFF pins can be safely left floating

if they are not used. The input fuse should not be omitted.

The fuse serves two purposes:

1) It prevents unlimited current from flowing in the case of a

catastrophic system failure

2) UL regulations for telecom equipment require the use of a

fuse. See CALEX Application Notes for more info on sizing

the input fuse.

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15 Watt TC Single Series DC/DC Converters

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

4eco# 041007-1

Solution

According to the 15 Watt TC Single Series “Reflected Input

Ripple vs. Line Input” curve at 40 VDC input and 2.25 Amps

output (75% of rated load), the reflected input ripple can be

read as 650 mA RMS. From the derating guidelines the

capacitor’s rated voltage and ripple current can be determined.

Capacitor voltage rating is calculated as:

A capacitor selection can now be made. Look only at

controlled low ESR types (where the ESR is specified as a

maximum) because these usually have the highest ripple

current capability per unit volume.

Be careful to compare apples to apples. Some

manufacturers specify their capacitors at 85°C and others

specify at 105°C. The manufacturers give temperature derating

guidelines, so all capacitors should be normalized to your

maximum ambient (plus 5°C to account for self heating)

before making a selection. Since the 15 Watt TC Single Series

operates at 120 kHz the frequency usually does not have to

be derated since most modern low ESR capacitors are rated

at 100 kHz.

One note: The temperature derating multipliers are based

on the capacitor’s expected life at 105°C. The life of a

capacitor operating at a significantly lower temperature will

not be greater if the ripple current in the part is increased over

the 105°C rating. This means that a capacitor rated for 1 A

RMS current at 105°C and 2 A RMS at 50°C will have the same

life if used at either point while the same capacitor used at 1

A RMS and 50°C will have a longer life.

Suggested Capacitor Sources

Suitable capacitors can be acquired from the following sources:

United Chemi-Con SXE, RXC, RZ and RZA Series

Suggested Part: SXE100VB221M12.5X35LL

220µF, 100V, 105°C Rated

ESR=0.087 ohms

Allowable Ripple=1.45 A @ 105°C

Nichicon PR and PF

Suggested Part: UPR2A102MPH

1000µF, 100V, 105°C Rated

ESR=0.047 ohms

Allowable Ripple=1.32 A @ 105°C

Sizing The Input Capacitor

For maximum reliability the TC Single Series must use a

capacitor of sufficient ripple handling capability connected

across the input pins. The probable result of undersizing (over

stressing) this capacitor is increased self heating, shortening

of the capacitors and hence shortening of your systems’ life.

Oversizing the capacitor can have a negative effect on your

product’s cost and size, although this kind of overdesign does

not result in shorter life of any components. There is no one

optimum value for this capacitor. The size and capacity are

dependent on the following factors:

1) expected ambient temperature and your temperature

derating guidelines

2) your ripple current derating guidelines

3) the maximum load expected on the converter

4) the minimum input voltage expected on the converter

5) the statistical probability that your system will spend a

significant amount of time at any worst case extreme

Factors 1 and 2 are determined by your system design

guidelines. These can range from 50% to 100% of the

manufacturer’s rated maximum, although a usual derating

factor is 70% of manufacturer’s maximum limit. 70% derating

means that if the capacitor manufacturer says their capacitor

can do 1 A RMS and 100 VDC you would not use the part over

700 mA RMS and 70 VDC. Surge voltage rating should also

be evaluated against any expected voltage surges when

selecting a capacitor working voltage.

Factors 3 and 4 realistically determine the worst case ripple

current. The reflected ripple current increases with output

load and increases as the input voltage decreases. So if you

are running with a solid 48 VDC input and at 50% load your

capacitors required ripple current rating would decrease by

more than 2:1 from what would be required for operation at 20

VDC with full load (see the “Input Reflected Ripple” curve).

Factor 5 is not easy to quantify. At CALEX, we can make

no assumptions about a customer’s system so we design for

continuous operation at worst case extremes.

Example Of Capacitor Sizing

Given the following conditions, select the minimum size

capacitor needed to provide reliable performance:

Converter ......................................... 48S5.3000TC

Minimum Input Voltage .................... 40 VDC

Maximum Input Voltage ................... 52 VDC

Maximum Load ................................ 2.25 Amps

Maximum Ambient Temperature ..... 40°C

Your Capacitor Voltage

Derating Guideline ........................... 70% of Maximum

Specification

Your Capacitor Current

Derating Guideline ........................... 70% of Maximum

Specification

V = 1 x

Maximum Expected Input

Voltage Derating Factor

V = 1 x 52 = 74

Volts or greater

0.7

I = 1 x

Reflected Ripple

Current Derating Factor

= 1 x 650

= 0.93

A RMS or greater at 45°C

0.7

(40°C ambient + 5°C for self heating)

15 Watt TC Single Series DC/DC Converters

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

5eco# 041007-1

USING TRIMPOT

USING FIXED RESISTORS

10 K LOAD

LOAD

TRIM

DOWN

TRIM

+ OUT

TRIM

CMN

+ OUT

TRIM

CMN

Panasonic HFE Series

Suggested Part: ECEA2AFE221L

220µF, 100V, 105°C Rated

ESR=0.089 ohms

Allowable Ripple=1.04 A @ 105°C

The suggested capacitors will work for any line and load

condition, however, they may be oversized for your application.

Low Noise Input Filtering Circuit

To reduce the input reflected ripple to less than 50 mA peak

to peak the circuit shown in Figure 2 may be used. Toroid core

inductors have theoretically lower radiated noise than a rod

core. Use reasonable caution when selecting an inductor

other than the one specified. Nearly any 105°C rated capacitor

can be used for the 10µF / 100V part. To prevent input filter

peaking the ESR should be in the range of 0.5 to 2 ohms. Do

not use the lowest ESR capacitor available for this part. This

will render the filter ineffective.

FIGURE 2. Low noise input filter circuit

Remote ON/OFF Circuit Operation

The remote ON/OFF pin is best applied as follows:

To turn the unit off, the ON/OFF pin should be tied to the -

Input pin. This is best done by an open collector arrangement

or contact closure.

To turn the unit on, let the ON/OFF pin float.

If the remote ON/OFF pin is not used, it may be safely left

floating. There is a 100K internal pull-up resistor inside the

unit to +9 volts DC.

Other applications of the ON/OFF function can be found in

the application note, “Understanding the Remote ON/OFF

Function”.

Proper Application Of The Trim Pin

The trim pin is used to adjust the output voltage slightly to

compensate for voltage drops in the system’s wiring. Figure

3 shows the proper application of the trim pin. Either a 10K

trimpot or fixed resistors may be used.

Other applications for the TRIM function can be found in the

CALEX application note: “Applying the Remote Sense and

Trim Functions on DC/DC Converters.”

THIS CAPACITOR IS REQUIRED

FOR PROPER OPERATION

FUSE 50 µH, 1000 mA

TO INPUT

SOURCE

10 µF

100 V

+ INPUT

- INPUT

Use one resistor for either trim up or trim down. The values

can range from infinity to zero ohms with zero ohms providing

the most trim.

Temperature Derating Guidelines

Care must be taken in the application of all power devices. Be

sure to account for the self heating in your instrument due to

the power converter and the loads. For minimum temperature

gradient, the hottest components should be mounted at the

bottom of your system (bottom of a vertical PCB) and the

coolest components at the top of the system. This will help to

even the temperature of the entire system and prevent

temperature gradients.

The 15 Watt TC Single Series has a thermal impedance of

10°C per package watt dissipated. During normal operation

the 15 Watt TC Single Series can be expected to run at 80%

efficiency at 48 VDC and full load. This means that the 15 Watt

TC Single Series is dissipating nearly 4 Watts internally at full

load. This, therefore, translates to a package temperature rise

of about 40°C (10°C/watt x 4 watts dissipated).

The maximum rated case temperature for the 15 Watt TC

Series is 90°C. This means that, in the absence of other heat

sources (including the load that the converter is powering)

and with at least 3 inches of clearance, the 15 Watt TC Single

Series can be expected to operate at an ambient of 50°C.

Additional heat sinks or cooling air flow can extend the

ambient temperature of operation significantly.

Figure 3. Output trim methods

15 Watt TC Single Series DC/DC Converters

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

6eco# 041007-1

20 25 30 35 40 45 50 55 60

LINE INPUT(VOLTS)

EFFICIENCY(%)

EFFICIENCY Vs. LINE INPUT VOLTAGE

100% FULL LOAD

50% FULL LOAD

0 102030405060708090100

LOAD (%)

EFFICIENCY (%)

EFFICIENCY Vs. LOAD

LINE = 20VDC

LINE = 48VDC

LINE = 60VDC

20 25 30 35 40 45 50 55 60

LINE INPUT (VOLTS)

0.20

0.40

0.60

0.80

1.00

REFLECTED RMS RIPPLE (AMPS)

INPUT RIPPLE Vs. LINE INPUT

100%

FULL LOAD

75%

FULL LOAD

50%

FULL LOAD

0 102030405060

LINE INPUT (VOLTS)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

INPUT CURRENT (AMPS)

INPUT CURRENT Vs. LINE INPUT VOLTAGE

100% LOAD

50% LOAD

0 20 40 60 80 100 120 140 160 180

OUTPUT LOAD (%)

100

120

OUTPUT VOLTAGE (%)

OUTPUT VOLTAGE Vs. OUTPUT LOAD

10 100 1000 10000 100000 1000000

FREQUENCY (Hz)

.01

OUTPUT IMPEDANCE (OHMS)

OUTPUT IMPEDANCE Vs. FREQUENCY

48S5.3000TC

48S15.1000TC

-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90

CASE TEMPERATURE (Deg C)

-0.5

-0.4

-0.3

-0.2

-0.1

-0.0

0.1

0.2

NORMALIZED OUTPUT (%)

OUTPUT VOLTAGE Vs CASE TEMPERATURE

Typical Performance (Tc=25°C, Vin=Nom VDC, Rated Load, 48S12.1250TC)