Linear Technology 968A-D Bedienungsanleitung

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 968A-D

ISOLATED DC/DC POWER CONVERTER

LT1952

DESCRIPTION

Demonstration circuit 968A-D is isolated input to high

current output 1/8th Brick footprint converter featur-

ing the LT®1952 switching controller. The DC968-D

converts isolated 36V to 75V input to 28V output and

provides over 4A of output current. The converter op-

erates at 300kHz with efficiency up to 95%. With

proper amount of airflow, the DC968-D converter can

generate up to 5A of output current. The DC968 can

be easily modified to generate output voltages in the

range from 0.6V to 48V. The output currents are lim-

ited by total output power of up to 200W. The other

available versions of DC968A are:

DC968A-A 36-75Vin to 3.3V@30A

DC968A-B 18-36Vin to 5V@20A

DC968A-C 36-75Vin to 12V@12A

Also, the DC968 can be modified for other input volt-

ages like 8V-36V, 18V-75V, 44V-52V, and so on. The

wider input voltage range will decrease the converter

efficiency. Therefore, narrow input voltage range will

be more desirable.

The DC968 circuit features soft-start which prevents

output voltage overshoot on startup or when recover-

ing from overload condition.

The DC968 has precise over-current protection circuit

that allows for continuous operation under short cir-

cuit conditions. The low power dissipation under

short circuit conditions insures high reliability even

during short circuits.

The LT1952 can be synchronized to an external clock

of up to 400kHz. Please refer to LT1952 data sheet for

design details and applications information.

Design files for this circuit board are available. Call

the LTC factory.

LT is a trademark of Linear Technology Corporation

Table 1.

Performance Summary

PARAMETER CONDITION VALUE

Minimum Input Voltage IOUT = 0A to 4A 36V

Maximum Input Voltage IOUT = 0A to 4A 72V

VOUT VIN = 36V to 72V, IOUT = 0A to 4A 28V ±3%

Typical Output Ripple VOUT VIN = 36V to 72V, IOUT = 0A to 4A 100mVP–P

Nominal Switching Frequency 300kHz

QUICK START PROCEDURE

Demonstration circuit 968 is easy to set up to evalu-

ate the performance of LT1952 circuit. Refer to Fig-

ure 1 for proper measurement equipment setup and

follow the procedure below:

NOTE:

When measuring the input or output voltage

ripple, care must be taken to avoid a long ground lead

on the oscilloscope probe. Measure the input or out-

put voltage ripple by touching the probe tip directly

across the Vin or Vout and GND terminals. See Figure

2. for proper scope probe technique.

With power off, connect the input power supply to

Vin and GND. Make sure that the input power sup-

Downloaded from Arrow.com.

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 968A-D

ISOLATED DC/DC POWER CONVERTER

ply has sufficient current rating at minimum input

voltage for the required output load.

Turn on the power at the input.

NOTE:

Make sure that the input voltage does not

exceed 75V.

Check for the proper output voltage.

Vout = 28V, +/-3%.

If there is no output, temporarily disconnect the

load to make sure that the load is not set too high.

Once the proper output voltage is established, ad-

just the load within the operating range and ob-

serve the output voltage regulation, ripple voltage,

efficiency and other parameters.

The DC968 is equipped with an output capacitor

CSYS (330uF) that approximates typical system

rail capacitance. If system board already has ca-

pacitance of similar value CSYS can be removed.

Figure 1. Proper Measurement Equipment Setup

Downloaded from Arrow.com.Downloaded from Arrow.com.

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 968A-D

ISOLATED DC/DC POWER CONVERTER

Figure 2. Scope Probe Placement for Measuring Input or Output Ripple

CHANGING THE OUTPUT VOLTAGE

To set the output voltage lower than 28V, change

the bottom voltage divider resistor connected to

LT4430 FB pin (see the simplified schematic on

page 5). For example, to get 24V output, change

R38 resistor value to 7.15k. However, keep in mind

that changing the transformer as well may increase

the efficiency. The schematic on page 6 shows all of

the components on the PCB. The schematic on

page 6 can be used as a reference if optional cir-

cuits need to be implemented.

To get higher than 28V output voltages transformer

with higher turns ratio may be required. Also, out-

put MOSFETs with higher voltage ratings may be

required. Please contact LTC factory for details.

PRIMARY MOSFET DRIVER LTC4440

The DC968 has an LTC4440 MOSFET driver U2. The

LTC4440 can be disabled if the efficiency is not im-

portant. If U2 is disabled, the DELAY pin of LT1952

should be readjusted to optimize the efficiency.

Please contact LT factory for assistance.

RESET CIRCUIT

The DC968 is equipped with an active reset circuit.

The active reset circuit is used in order to improve

the efficiency by 1% to 2%.

If the efficiency is not important, active reset circuit

can be disabled. In that case, MOSFET Q2 will need

to be replaced with a MOSFET with higher voltage

rating. Please contact LTC factory for help in select-

ing appropriate MOSFET. The active reset circuit

does not always help with the efficiency and is dis-

abled on DC968-A, -B and -C demo boards.

LT1952 DC968-D 28V @4A Output Efficiency

90%

91%

92%

93%

94%

95%

96%

12345

Iout [A]

Figure 3. High efficiency of DC968A-D allows the

board to be used in thermally critical applications

with outputs up to 5A.

OUTPUT LOAD STEP RESPONSE

The load step response of DC968A-D is very fast

even though relatively small amount of output ca-

pacitance is present (6.8uF ceramic and 330uF elec-

trolytic). This is thanks to fast error amplifier of

LT4430, optimal amount of current slope compen-

sation of LT1952, fast opto coupler and fast error

amplifier of LT1952. If higher load steps need to be

handled more output capacitance can be added in

order to keep the voltage transients at the desired

level. The load step transients are shown in Figure

Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 968A-D

ISOLATED DC/DC POWER CONVERTER

Figure 4. Fast transient response of DC968 is su-

perior to many competing power modules without

the additional output capacitors.

SOFT START FUNCTION

The DC968 features LT4430 opto coupler driver that

has soft start function which produces monotonic

startup ramp shown if Figure 5. The rise time of

output voltage is controlled by capacitor C19 that is

connected to OC (overshoot control) pin of LT4430.

Figure 5. The LT4430 opto coupler driver pro-

duces monotonic output voltage rise at startup

without output voltage overshoot.

DEBUGGING AND TESTING

The DC968 can easily be tested and debugged by

powering the bias circuit with a separate power

source. To place DC968 into debug mode remove

the resistor R1 and connect 48V, 100mA power

source to +Vb node (right side of R1). By doing

this, the primary PWM controller LT1952 can be

activated without the main primary power being

applied to +Vin.

To activate the secondary side MOSFET driver

(LTC3900) connect a 10V, 100mA power source to

collector of Q9 via 1A, 40V diode. That way the cur-

rent coming from DC968 bias supply will not be

able to flow back to 10V supply once the converter

is running.

Once the primary and secondary controllers are

running the MOSFET gate timing can be checked.

If the MOSFET gate timing is correct the main

power input can be applied to +Vin. The correct de-

lay from turn on of FG and gate of Q1 is usually in

the range from -100ns to +100ns. By slowly in-

creasing the +Vin from 0V to 48V the output voltage

and input current can be monitored. The input cur-

rent should not exceed 100mA without the output

load. If one of the MOSFETs is damaged, the input

current will exceed 100mA.

Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 968A-D

ISOLATED DC/DC POWER CONVERTER

Rcs1

0.010R

Cin1

3x2.2uF

+Vin

47R

R29

22K

Cu1

4.7uF

R23 1.5k

R24

82K

Vu1

R15 115k

R20

43.2k

C10

0.1u

Vu1

D10

BAT760

R3 41.2

C15

2.2nF, 2kV

C11

opt.

R28

442k

R22

13.3k

PHM21NQ15

PA0856.003

GND

MaxDC

FB=1.23V

Comp

Rosc

Vr=2.5V

Blank 9

Delay 12

OC 11

Sync

Isense 10

PGND 13

Out 14

Vin 15

Sout 16

LT1952-1

Sout

R33

158k C13

.47u

R26

220R

R30

1.2k

R14

33K

C23

1uF

Vfb

R13

22K

R42 0R

Co1

6.8uF, X7R

+Vo1

R17

560R PE-68386

Vaux

C14

C12

470p

R19

38.3K

CS-

CS+

Vcc

4FG 5

GND 6

Timer 7

Sync 8

LTC3900

R21

10k

R27

270R

R38

6.19k

R35

280k

R34

16.9k

C19

1uF, X5R

C16

.22u, 10V

C17

15n

+Vo1

Vaux

R31

10R

Vcc

FB 4

Opto 6

GND

2Comp 5

LT4430

C18

opt.

R18

10k

+Vin

PDZ9.1B

Vu1

BAS516

R11

82k

-Vin

+Vin

2.2R

R32

383k

PA2050.393

HAT2174

R16

56k

0.22u

BAS21H

PDZ9.1B

2.2R

10R

Q12

BC857BF

BAS516

Q10

PZTA42

+Vb

1.5mH

PS2801-1

Inp

Vcc

TS 4

Boost 6

GND

2TG 5

LTC4440-5

C21

220p

BAS516

Vu1

Out

D11

BAS516

GND

+Vout

220p

Sout

100p

680pF

BAS21H

Csys

330uF, 35V

C24

opt.

100p

C25

47n

R43

D12

BAS516

R4710k

C26

220p

R46

2.2k

R44

11.3k

Q13

IRF6217

Inp

Vcc

TS 4

Boost 6

GND

2TG 5

LTC4440

C28

0.1u C29

0.1u

Vu1

D14

BAS516

R45

10k

2A1

-Q1

RC2

Vcc 16

GND

B2 10

A2 9

-Q2 12

Q1 13

C1 14

RC1 15

R2 11

HC123

+5V

Out

D13

PDZ5.1B

C27

0.1u

R48

150R

C30

100p

+Vr2

+5V Sw0

Sw0

Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 968A-D

ISOLATED DC/DC POWER CONVERTER

Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.

Dieses Handbuch passt für folgende Modelle

Inhaltsverzeichnis

Andere Linear Technology Computerhardware Handbücher

Linear Technology

Linear Technology LTC4227-1 Kurzanleitung zur Einrichtung

Linear Technology

Linear Technology DC1599A Bedienungsanleitung

Linear Technology

Linear Technology DC2169A Kurzanleitung zur Einrichtung

Linear Technology

Linear Technology DC1500A Kurzanleitung zur Einrichtung

Linear Technology

Linear Technology DC2005A Bedienungsanleitung

Linear Technology

Linear Technology LTM9004 Bedienungsanleitung

Linear Technology

Linear Technology DC2355A Bedienungsanleitung

Linear Technology

Linear Technology DC2460A Kurzanleitung zur Einrichtung

Linear Technology

Linear Technology DEMO CIRCUIT 1324A Bedienungsanleitung

Linear Technology

Linear Technology DC2041A Bedienungsanleitung

Linear Technology

Linear Technology LTC2430 Bedienungsanleitung

Linear Technology

Linear Technology LTC6417 Bedienungsanleitung

Linear Technology

Linear Technology LTC3214 Bedienungsanleitung

Linear Technology

Linear Technology 1446 Bedienungsanleitung

Linear Technology

Linear Technology LTC3718 Bedienungsanleitung

Linear Technology

Linear Technology LT3669-2 Bedienungsanleitung

Linear Technology

Linear Technology DC1304A-A Bedienungsanleitung

Linear Technology

Linear Technology LTC2933 Bedienungsanleitung

Linear Technology

Linear Technology DC1920A Kurzanleitung zur Einrichtung

Linear Technology

Linear Technology LTC3126UFD Bedienungsanleitung

Linear Technology

Linear Technology 1791A Bedienungsanleitung

Linear Technology

Linear Technology DC2455A-C Kurzanleitung zur Einrichtung

Linear Technology

Linear Technology DC1007C Bedienungsanleitung

Linear Technology

Linear Technology CIRCUIT 630 Bedienungsanleitung

Beliebte Computerhardware Handbücher anderer Marken

EMC2

EMC2 VNX Series Betriebsanleitung

Panasonic

Panasonic DV0PM20105 Bedienungsanleitung

Mitsubishi Electric

Mitsubishi Electric Q81BD-J61BT11 Bedienungsanleitung

Gigabyte

Gigabyte B660M DS3H AX DDR4 Bedienungsanleitung

Raidon

Raidon iT2300 Bedienungsanleitung

National Instruments

National Instruments PXI-8186 Bedienungsanleitung

Hauppauge

Hauppauge WinTV-HVR-2250 Bedienungsanleitung

Kontron

Kontron CP6002 Bedienungsanleitung

Manhattan

Manhattan 702843 Bedienungsanleitung

Aphex

Aphex 230 Bedienungsanleitung

AMD

AMD Phenom II Betriebshandbuch

Intel

Intel NUC 12 Pro Bedienungsanleitung

dbx

dbx Zone Pro 1260 Bedienungsanleitung

Galaxy

Galaxy GHDX2-2430S-24F4D Bedienungsanleitung

Intel

Intel AXXRMFBU4 Bedienungsanleitung

Kontron

Kontron DIMM-PC/MD Bedienungsanleitung

ST X-NUCLEO-SAFEA1B Betriebsanleitung

STEINWAY LYNGDORF

STEINWAY LYNGDORF SP-1 Bedienungsanleitung