Linear Technology LT3790, DC2123B Demo Manual

DESCRIPTION

DEMO MANUAL DC2123B

LT3790

60V Four-Switch Synchronous

Buck-Boost Controller

The DC2123B is a 60V four-switch synchronous buck-boost
controller that demonstrates the high power capability
of the LT
output current is 5A. The switching frequency is 200kHz
and efficiency is as high as 98% for a 24V input.

The LT3790 is capable of high power operation. DC2123B
can be altered for increased output power with higher
minimum input voltage. If V
20V, I
changing RS2 to 4mΩ.

The operating input voltage range of DC2123B is from 8V
to 56V. The output voltage, EN/UVLO, and OVLO are all
programmed by resistor dividers. EN/UVLO is set so the
circuit will turn off when the input voltage falls below 8V
and will turn on when the input voltage rises above 9.6V.
OVLO is set to engage for input voltages above 57V.

Current sense resistors program input and output current
limits and also determine the monitoring voltages that
indicate input and output current. IVINMON provides a
30mV/1A voltage that is used to monitor the input cur
rent. Input current limit occurs at 33.3A and is set by
RIN1. ISMON provides a 160mV/1A voltage that is used
to monitor the output current. The output current limit is

7.5A and is set by RS2.

The demo circuit features MOSFETs that compliment the
5V gate drive of the LT3790 to achieve high efficiency. 60V
MOSFETs are used on the input side of the four-switch
topology while 40V MOSFETs are used on the output side.
Ceramic capacitors are used at both the circuit input and
output because of their small size and high ripple current
capability. In addition to ceramic capacitors, there is an
aluminum polymer capacitor on the output that assures
feedback loop stability, even at low temperatures. The
input has an aluminum electrolytic capacitor in addition
to ceramic capacitors. A two-stage L-C input filter can
easily be added for electro-magnetic compatibility. The

®

3790. The output is 24V and the maximum

remains always above

IN

can be increased to 12A+ (for 290W output) by

OUT

pcb has large copper planes and extensive vias for thermal
performance.

The CLKOUT output and the SYNC input can be used to
synchronize switching between two or more DC2123B
circuits. A resistor from SYNC to ground must be removed
prior to using the SYNC input.

SHORT and C/10 are open-collector status flag outputs and
are pulled up to the INTV
the CCM pin to C/10 and causes the circuit to change to
discontinuous conduction mode (DCM) when C/10 is active
at light load currents. CCM can also be connected with a
resistor to INTV
tion mode (CCM) operation over the entire load range.

The CTRL input is pulled up to the V
resistor to set the output current limit to its maximum,
and an external voltage on CTRL can be used to lower the
current limit if the resistor is removed. A capacitor at the
SS pin programs soft-start and additionally SS is pulled
up to the V

-

frequency is adjustable with a resistor.

The demo circuit is designed to
many other applications, including the example schemat
ics in the data sheet. Consult the factory for assistance.

High power operation, four-switch buck-boost topology,
fault protection and full monitoring make the LT3790
attractive for high power voltage regulator circuits and
also circuits that require output current regulation such
as battery chargers. The LT3790EFE is available in a
thermally enhanced 38-lead TSSOP package. The LT3790
data sheet must be read in conjunction with this demo
manual to properly use or modify demo circuit DC2123B.

Design files for this circuit board are available at

http://www.linear.com/demo/DC2123B

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.

REF

instead of C/10 for continuous conduc-

CC

pin through a 100k resistor. The switching

pin voltage. A resistor shorts

CC

pin through a 0Ω

REF

be easily reconfigured to

-

dc2123bfa

1

DEMO MANUAL DC2123B

PERFORMANCE SUMMARY

PARAMETER CONDITIONS MIN TYP MAX UNITS

Minimum Input Voltage, V

Maximum Input Voltage, V

Maximum Output Current 8V < V

Input EN Voltage, V

Input UVLO Voltage, V

Input OVLO Turn-Off Voltage, V

Input OVLO Turn-On Voltage, V

Output Voltage V

Efficiency V

Switching Frequency R18 = 147k 200 kHz

Input Current Limit RIN1 = 0.0015Ω 33 A

Output Current Limit RS2 = 0.008Ω 7.5 A

OUT

PVIN

PVIN

PVIN(EN)

PVIN(UVLO)

PVIN(OVLO turn-off)

PVIN(OVLO turn-on)

Specifications are at TA = 25°C

V

= 24V I

OUT

V

= 24V I

OUT

PVIN

R3 = 88.7k, R4 = 499k, V

R3 = 88.7k, R4 = 499k, V

R11 = 27.4k, R1 = 499k, V

R11 = 27.4k, R1 = 499k, V

R19 = 71.5k, R34 = 1.37k, R20 = 3.83k 23.5 24.5 V

= 24V, I

PVIN

≤ 5A 8 V

OUT

≤ 5A 56 V

OUT

< 56V, CTRL = V

= 5A 98 %

OUT

REF

Rising 9.6 V

PVIN

Falling 8.0 V

PVIN

Rising 57.6 V

PVIN

Falling 56.2 V

PVIN

5 A

QUICK START PROCEDURE

It is easy to set up demonstration circuit DC2123B to
evaluate the performance of the LT3790. Refer to Figure1
for the proper measurement equipment setup and follow
the procedure below:

NOTE: Make sure that the voltage applied to PV

does

IN

not exceed the absolute maximum voltage rating of 60V
for the LT3790.

1. Connect the EN/UVLO terminal to ground with a clip-on
lead. Connect the power supply (with power off), load,
and meters as shown.

2. After all connections are made, turn on the input power
and verify that the input voltage is between 8V and56V.

3. Remove the clip-on lead from EN/UVLO. Verify that the
output voltage is 24V.

NOTE: If the output voltage is low, temporarily disconnect
the load to make sure that it is not set too high.

4. Once the proper output voltage is established, adjust
the input voltage and load within the operating ranges
and observe the output voltage regulation, ripple volt
age, efficiency and other parameters.

-

2

dc2123bfa

QUICK START PROCEDURE

VIN = 12V

VIN = 24V

LOAD CURRENT (A)

01234

5

80

85

90

95

100

EFFICIENCY (%)

dc2123 F02

DEMO MANUAL DC2123B

Figure 1. Proper Measurement Equipment Setup for DC2123B

Figure 2. Efficiency

dc2123bfa

3

DEMO MANUAL DC2123B

QUICK START PROCEDURE

VIN = 14V

VIN = 24V

VIN = 54V

Figure 3. Output Voltage Ripple at 5A Output Current, V

VIN = 14V

VIN = 24V

VIN = 54V

Figure 4. Output Voltage Load Transient Response, V

OUT

= 24V, I

= 24V, 25MHz Bandwidth

OUT

= 2.5A to 5A to 2.5A, 25MHz Bandwidth

OUT

4

dc2123bfa

QUICK START PROCEDURE

(V)

V

OUT

DEMO MANUAL DC2123B

30

25

20

15

10

5

0

0

1 2

3 4 5 6 87

I

(A)

OUT

dc2009a F05

Figure 5. V

in Current Limit, VIN = 24V

OUT

DIFFERENCES BETWEEN LT3790 AND LT3791-1

The LT3790 is an improved version of the LT3791-1 and
is recommended for use in new designs. Some external
component values may change, but otherwise, the LT3790
is functionally equivalent to the LT3791-1. The differences
between the two products are:

1. The LT3790 has a 60mV (typical) full-scale V

(ISP-ISN)

current sense voltage, compared to 100mV (typical) for
the LT3791-1. This change allows lower power current
sense resistors to be used for most applications.

2. The LT3790 CTRL pin linear range is from 0V to 1.1V,
and has a turn-off threshold of 50mV(typical), compared
to a 200mV to 1.1V linear range and 175mV (typical)

turn-off threshold for the LT3791-1. These changes
make it easier to parallel two or more LT3790 ICs for
higher power levels.

3. The LT3790 C/10 pin pulls low when the V

is less than 1/10 full scale, compared to the LT3791-1,
where C/10 pulls low when both V
1/10 full scale and V
Since the C/10 pin is used to allow DCM mode for some
applications, this change ensures that negative current

not occur at light loads for a broader range of

does
applications.

(ISP-ISN)

(ISP-ISN)

is greater than 1.15V(typical).

FB

voltage

is less than

dc2123bfa

5

DEMO MANUAL DC2123B

PARTS LIST

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 2 CC1, CSS1 CAP., X7R 33nF 25V 10% 0603 AVX 06033C333K AT1A

2 1 C1 CAP., X5R 0.47µF 16V 20% 0402 TDK C1005X5R1C474MT

3 3 C2, C12, C13 CAP., X5R 0.1µF 16V 10% 0402 TDK C1005X5R1C104KT

4 1 C3 CAP., X5R 1µF 100V 10% 1206 TAIYO YUDEN HMK316BJ105KL-T

5 1 C4 CAP., X5R 4.7µF 10V 10% 0603 TAIYO YUDEN LMK107BJ475KA

6 2 C6, C7 CAP., X7S 4.7µF 100V 10% 1210 TDK C3225X7S2A475K200AB

7 2 C10, C11 CAP., ALUM. ELECT. 47µF 80V ± 20% UNITED CHEMI-CON EMZA800ADA470MJA0G

8 2 C14, C15 CAP., X5R 4.7µF 50V 20% 1210 TAIYO YUDEN UMK325BJ475MM-T

9 2 C20, C30 CAP., HYBRID COND. POLYMER 220µF 35V 20% SUN ELECTRONIC INDUSTRIES 35HVP220M

10 1 C29 CAP., X7R 0.033µF 16V 10% 0402 TDK C1005X7R1C333K

11 2 D1, D2 SCHOTTKY BARRIER 100V SOD323(SC-90) NXP SEMI. BAT46WJ

12 1 L1 INDUCTOR, 10µH SER2900 COILCRAFT, SER2918H-103KL

13 2 M1, M2 MOSFET-N CHANNEL, 60V, TDSON-8 INFINEON, BSC100N06LS3 G

14 2 M3, M4 MOSFET-N CHANNEL, 40V, TDSON-8 INFINEON, BSC032N04LS

15 1 RC1 RES., CHIP 7.5k 0.06W 5% 0402 VISHAY CRCW04027K50JNED

16 1 RIN1 RES., 0.0015Ω 1W 1% 2512 PANASONIC, ERJ-M1WTF

17 1 RS1 RES., 0.002Ω 1W 1% 2512 PANASONIC, ERJ-M1WTF2M0U

18 1 RS2 RES., 0.008Ω 1W 1% 2512 PANASONIC, ERJ-M1WSF8M0U

19 2 R1, R4 RES., CHIP 499k 0.06W 1% 0603 VISHAY CRCW0603499KFKEA

20 1 R3 RES., CHIP 88.7k 0.06W 1% 0402 VISHAY CRCW040288K7FKED

21 1 R5 RES., CHIP 51Ω 0.06W 5% 0402 NIC, NRC04F51R0TRF

22 2 R6, R10 RES., CHIP 200k 0.06W 5% 0603 VISHAY CRCW0603200KJNEA

23 1 R11 RES., CHIP 27.4k 0.06W 1% 0402 VISHAY CRCW040227K4FKED

24 1 R16 RES., CHIP 200k 0.06W 5% 0402 VISHAY CRCW0402200KJNED

25 1 R17 RES., CHIP 100k 0.06W 5% 0402 VISHAY CRCW0402100KJNED

26 1 R18 RES., CHIP 147k 0.06W 1% 0402 VISHAY CRCW0402147KFKED

27 1 R19 RES., CHIP 71.5k 0.06W 1% 0603 VISHAY CRCW060371K5FKEA

28 1 R20 RES., CHIP 3.83k 0.06W 1% 0402 VISHAY CRCW04023K83FKED

29 1 U1 I.C., 60V BUCK-BOOST VOLT. REG. LINEAR TECH. CORP. LT3790EFE#PBF

1M5U

6

dc2123bfa

DEMO MANUAL DC2123B

PARTS LIST

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Additional Demo Board Circuit Components

1 0 C5, C8, C9, C16, C17, C18 (Opt) CAP., 1210

2 0 C19 (Opt) OPTIONAL

3 0 C21, C22, C28, CC2 CAP., 0603

4 0 C23 OPTIONAL

5 0 C24, C25, C26, C27 (Opt) OPTIONAL

6 0 D3, D4 (Opt) SCHOTTKY DIODE, SMB

7 0 D5, D6 (Opt) DIODE, SOD-123

8 0 D7 (Opt) DIODE, SOD-523

9 0 L2, L3 (Opt) OPTIONAL

10 0 M5, M6, M7, M8, M12 (Opt) OPTIONAL

11 0 M9, M10, M11 (Opt) OPTIONAL

12 0 R2, R23, R24, R26-R32 RES., 0603 OPTIONAL

13 1 R7 RES., CHIP 0Ω 1206 YAGEO, RC1206FR-070RL

14 0 R8, R9, R25 Res., 0402 OPTIONAL

15 3 R12, R14, R22 RES., CHIP 0Ω 0402 VISHAY CRCW04020000Z0ED

16 2 R13, R21 RES., CHIP 0Ω 0603 VISHAY CRCW06030000Z0EA

17 1 R34 RES., CHIP 1.37k 0.06W 1% 0603 PANASONIC ERJ-3EKF1371V

Hardware: For Demo Board Only

1 4 E1, E2, E19, E20 CONNECTOR, BANANA JACK KEYSTONE 575-4

2 13 E3, E5, E6, E7, E8, E9, E10, E11, E12,

E13, E14, E21, E22

3 5 E4, E15, E16, E17, E24 TURRET, TESTPOINT MILL MAX 2501-2-00-80-00-00-07-0

4 0 E18 (Opt) OPTIONAL

5 0 E23 (Opt) OPTIONAL

6 4 MH1-MH4 STANDOFF, NYLON 0.50" KEYSTONE, 8833 (SNAP-ON)

TURRET, TESTPOINT MILL MAX 2308-2-00-80-00-00-07-0

dc2123bfa

7

DEMO MANUAL DC2123B

SCHEMATIC DIAGRAM

IVINN

PVIN

RIN1

C11

C10

C9

C8

C7

C6

C5

1%

0.0015

47µF

+

47µF

+

(Opt)

(Opt)

4.7uF

4.7uF

(Opt)

R7

R5515%

2512

80V

80V

1210

1210

100V

100V

1210

1210

1210

0 Ohm

1206

INTVCC

R20

3.83k

M3

BSC032N04LS

3

D3

SMB

(Opt)

BG1

M2

BSC100N06LS3

18

BG1

LT3790EFE

VREF

6

VREF

R12

0 Ohm

C2

0.1µF

0402

R8

(Opt)

R10

200k

5%

R6

200k

5%

INTVCC

SNSP

27

SHORT5C/10

*SHORT

0603

0603

SNSP

RS1

4

*C/10

0.0021%2512

BG2

28

19

SNSN

IVINMON8ISMON

7

TP6

D1

BAT46WJ

10V

4.7µF

VIN

D2

IVINN

IVINP

VOUT

BAT46WJ

13

INTVCC

EN/UVLO

9

PVIN

VOUT

E19

RS2

BST115BST2

R9

R3

88.7k

ISP

22

(Opt)

R1

24V 5A

0.008

499k

E20

1.37k

0603

R34

R22

0 Ohm

2512

M4

BSC032N04LS

D4

C13

0.1µF

0402

C12

0.1µF

0402

TG1

M1

BSC100N06LS3

14

OVLO

38

R11

0603

GND

R19

C21

SMB

(Opt)

L1

10µH

SER2918H-103KL

TG1

1

27.4k

TP5

71.5k

12

SW1

16

CTRL

0603

(Opt)

SW1

U1

OUT

E18

(Opt)

C30

220µF

35V

+

C20

220µF

35V

+

C19

(Opt)

12.5mmDia.

Thru‐Hole

+

C18

(Opt)

1210

C17

(Opt)

1210

C16

(Opt)

1210

C15

4.7µF

50V

1210

C14

4.7µF

50V

1210

C4

INTVCC

C3

1µF

100V

1206

12

11

C1

0402

0.47µF

10

499K

0603

R4

R2

(Opt)

0603

VIN

SNSP

BG1

SW1

TG1

ISP

PWM

FB

TG2

SW2

BG2

*C/10

VREFSS*SHORT

PWMOUT

INTVCC

R21

0603

0 Ohm

SW2

FB

TG2

PWMOUT

PWMSS

3

25

31

26

37

24

21

FB

ISP

R14

R13

0 Ohm

INTVCC

0 Ohm

0603

ISN

PWM

PWMOUT

SS

CCM

2

32

C29

0.033µF

0402

CSS1

33nF

R16

R17

5%

VREF

100k

5%

200k

PGND
PGND

SGND
SGND

TEST1

VC

RT

TP3

TP4

17
20

39
30

29

36

CC2

OPT

CC1

33nF

RC1

5%

7.5k

35

R18

147k

200kHz

TG2

BG2

SW2

SYNC

CLKOUT

34

33

TP2

TP1

E1

PVIN

E2

8V - 56V

GND

E3

VIN

8V - 56V

E5

E4

GND

8

EN/UVLO

E7

E6

CTRL

OVLO

E8

E9

E10

C/10

SHORT

E11

IVINMON

ISMON

E12

E13

CLKOUT

SYNC

GND

E16

E17

GND

GND

NOTE: UNLESS OTHERWISE SPECIFIED.

ALL CAPACITORS 0603.

ALL RESISTORS 0402 1%.

E15

E14

GND

dc2123bfa

SCHEMATIC DIAGRAM

DEMO MANUAL DC2123B

INTVCC

ISP

PWM

TG2

ISP

M8

(Opt)

PG-TDSON-8

R29

TG1

(Opt)

SW1

0603

BG1

SNSP

TG2

BG2

M7

SW2

(Opt)

R30

FB

BG2

PWMOUT

PG-TDSON-8

0603

(Opt)

*C/10

VREF

VREF

R31

SS

(Opt)

0603

*SHORT

M10

SOT-23

(Opt)

INTVCC

E22

INTVCC

LED-

E23

(Opt)

M12

(Opt)

M11

(Opt)

SS

R32

(Opt)

0603

E24

LFPAK

SOT-23

PWMOUT

C28

(Opt)

GND

SW1 SW2

D6

M6

BG1

ISP

(Opt)

IVINN

TG1

M5

(Opt)

PG-TDSON-8

R24

VIN IVINN

D5

(Opt)

SW1 SW2

0603

(Opt)

SOD-123

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa­tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

(Opt)

PG-TDSON-8

R23

(Opt)

SOD-123

SNSP SNSP

0603

ISP

E21

PWM

PWM

R27

(Opt)

VREF

0603

R28

R26

*SHORT

(Opt)

0603

C22

(Opt)

(Opt)

0603

D7

FB

SOD-523

(Opt)

R25

(Opt)

L3

4.7µH
(Opt)

7443551470

Wurth Electronik

C27

4.7µF

100V

1210

(Opt)

C26

4.7µF

100V

1210

(Opt)

*C/10

L2

4.7µH
(Opt)

7443551470

M9

(Opt)

SOT-23

PVIN PVINPVIN

Wurth Electronik

C25

4.7µF

100V

1210

(Opt)

C24

4.7µF

100V

1210

(Opt)

C23

47µF

80V

(Opt)

+

10mm Dia. Surface Mount

dc2123bfa

9

DEMO MANUAL DC2123B

DEMONSTRATION BOARD IMPORTANT NOTICE

Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:

This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.

If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.

The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).

No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,

customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.

LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.

Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and

observe good laboratory practice standards. Common sense is encouraged.

This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application
engineer.

Mailing Address:

Linear Technology

1630 McCarthy Blvd.

Milpitas, CA 95035

Copyright © 2004, Linear Technology Corporation

Linear Technology Corporation

10

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone] ● www.linear.com

dc2123bfa

LT 0117 REV A • PRINTED IN USA

 LINEAR TECHNOLOGY CORPORATION 2014