DEMO MANUAL DC1523A
LTC3789EGN:
High Efficiency Synchronous
4-Switch Step-Up/Step-Down
DC/DC Converter
DESCRIPTION
Demonstration circuit 1523A features the LTC
®
3789EGN,
a high efficiency switching step-up/down controller. The
DC1523A input range is from 5V to 36V. The output volt-
age is 12V. The board is capable of delivering up to 5A of
output current over the input voltage range.
The LTC3789EGN is a high performance switching regula-
tor controller designed to regulate the output using input
voltages above, below or equal to the output voltage.
Synchronous operation provides very high efficiency, up
to 97%. Constant frequency current mode architecture
allows phase-lockable frequency from 200kHz to 600kHz.
An accurate output current limit provides support for
battery charging. A wide input and output range with
smooth transfer function through all operating modes
makes the product ideal for automotive, telecom and
battery systems.
The MODE/PLLIN pin can select between pulse skipping
mode and forced continuous mode operation and allows
the IC to be synchronized to an external clock. A Power
Good output pin indicates when the output is within 7.5%
of its set point.
Design files for this circuit board are available at
http://www.linear.com/demo
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.
PERFORMANCE SUMMARY
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
Output Voltage V
OUT
Regulation
Maximum Continuous Output Current
Default Operating Frequency
External Clock Synchronous Frequency Range
Efficiency
Load Transient
V
IN
= 5V to 36V, I
OUT
= 5A
V
IN
= 5V to 36V, I
OUT
= 0A to 5A
Some Airflow May be Needed at Low Input
Voltage and Continuous Full Load
R3 = 121k
CONDITIONS/ NOTES
VALUE
5V
36V
12V ±2%
5A DC
400kHz
200kHz to 600kHz
88% to 97%. See Figures 3 and 6
See Figure 5
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DEMO MANUAL DC1523A
QUICK START PROCEDURE
Demonstration circuit 1523A is easy to set up to evalu-
ate the performance of the LTC3789EGN. Please refer to
Figure 1 for proper measurement equipment setup and
follow the procedure below.
1. With power off, connect the input supply, load and
meters as shown in Figure 1. Preset the load to 0A and
VIN supply to 0V.
2. Set the current limit of the input supply high enough
so that the bench supply does not go into current limit
mode. Figure 2 shows input current as a function of
input voltage, at full load. Input current can reach 13A
at 5V input voltage.
3. Place jumpers in the following positions:
JP1
RUN
ON
JP2
MODE
CCM
4. Turn on the power at the input. Increase V
IN
to between
5V and 36V. The circuit will start and the output voltage
will regulate at 12V ±2%. The current draw at no load
is 20mA to 60mA depending on the input voltage.
5. Apply load and observe output voltage regulation, ripple
voltage, efficiency and other parameters. Efficiency and
power loss at full load is shown in Figure 3. Continuous
operation with full power and low input voltage may
require some airflow.
+
POWER
SUPPLY
A
A
+
V
V
LOAD
–
–
DC1523A F01
Figure 1. Proper Measurement Equipment Setup
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DEMO MANUAL DC1523A
QUICK START PROCEDURE
14
12
10
CURRENT (A)
8
6
4
2
0
5
10
15
25
20
V
IN
(V)
30
35
40
I
IN
I
OUT
100
98
96
EFFICIENCY (%)
EFFICIENCY
94
92
90
88
86
84
0
5
10
15
20
V
IN
(V)
DC1523A F02
DC1523A F03
8
7
6
POWER LOSS (W)
5
4
POWER LOSS
3
2
1
25
30
35
40
0
Figure 2. Input Current at Full Load (12V at 5A Out)
Figure 3. Efficiency and Power Loss at Full Load. The Power
Loss is Highest in Boost Mode Due to the High Inductor Current,
and Drops as Input Voltage Increases. Switching Losses Again
Increase when V
IN
> V
OUT
. All Four MOSFETs are Switching in
Buck-Boost Mode and This Shows Up as a Small Increase in
Losses When V
IN
= 11V to 15.5V
Figure 4. Output Ripple Voltage at 24V
IN
(Top), 12V
IN
(Middle),
6V
IN
(Bottom). Measured Across C
OUT1
, BW = 20MHz, 100mV/Div
98
Figure 5. Load Transient Response
96
14
EFFICIENCY (%)
94
12
10
V
OUT
(V)
5
DC1523 F06
92
6V
9V
12V
18V
0
1
3
2
LOAD (A)
4
24V
30V
36V
8
6
4
2
0
0
1
2
4
3
LOAD (A)
5
6
90
88
Figure 6. Efficiency at Various Input Voltages
DC1523A F07
Figure 7. Output Current Limit. (V
IN
= 12V. The Easiest Way to Do
This Test is with an Active Load in Voltage Mode)
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DEMO MANUAL DC1523A
PARTS LIST
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
QTY
1
2
1
1
4
2
4
1
1
1
1
1
1
1
1
2
2
1
1
1
1
2
1
1
1
1
2
4
1
1
3
2
1
1
1
1
1
1
1
1
1
REFERENCE
CC1
CC2, CSS
CIN1
COUT1
C1, C2, C16, C17
C4, C22
C5, C6, C9, C25
C10
C12
C13
C14
C15
C18
C24
D2
D7, D4
D5, D6
D8
L1
Q2
Q4
Q3, Q5
RC
RFB1
RFB2
R1
R2, R18
R3, R4, R13, R14
R5
R7
R8, R11, R26
R10, R9
R20
R21
R24
R25
R28
R29
R30
R31
U1
PART DESCRIPTION
CAP C0G, 1000pF 50V, 10% 0603
.,
,
CAP X7R, 0.01μF 50V, 10% 0603
.,
,
CAP Alum, 270μF 50V, 20%
.,
,
CAP OS-CON, 330μF 16V, 20%
.,
,
CAP X7R, 22μF 16V, 20% 1210
.,
,
CAP X7R, 0.22μF 16V, 20% 0603
.,
,
CAP X7R, 3.3μF 50V, 20% 1210
.,
,
CAP X7R, 2.2μF 10V, 10% 0603
.,
,
CAP NPO, 390pF 100V, 10% 1206
.,
,
CAP NPO, 1800pF 100V, 10% 1206
.,
,
CAP X7R, 0.1μF 50V, 10% 0603
.,
,
CAP X7R, 1μF 50V, 20% 1206-1210
.,
,
CAP X7R, 10μF 10V, 20% 1206
.,
,
CAP X7R, 1μF 16V, 20% 0603
.,
,
DIODE, BAS16, SOT23
SCHOTTKY REC., DFLS160, PowerDI-123
SCHOTTKY RECT., B240A SMA
ZENER DIODE, 5.1V, BZX84C5V1, SOT23
INDUCTOR, 4.7μH
MOSFET N-CHAN., 40V
MOSFET N-CHAN., 40V
MOSFET N-CHAN., SiR496DP 20V
,
RES., CHIP 14.7k, 0.1W, 1% 0603
.,
RES., CHIP 113k, 0.1W, 1% 0603
.,
RES., CHIP 8.06k, 0.1W, 1% 0603
.,
RES., CHIP 5.6Ω, 0.1W, 1% 0603
.,
Sensor Res., 0.01Ω, 1W, 2%, RL3720W
RES., CHIP 100Ω, 0.1W, 5%, 0603
.,
RES., CHIP 15Ω, 0.125W, 1% 0603
.,
RES., CHIP 100k, 0.1W, 1% 0603
.,
RES., CHIP 10Ω, 0.1W, 5% 0603
.,
RES., CHIP 1.24k, 0.1W, 1% 0603
.,
Sensor Res., 0.004Ω, 1W, 2%, RL3720W
RES., CHIP 121k, 0.1W, 1% 0603
.,
RES., CHIP 10k, 0.1W, 1% 0603
.,
RES., CHIP 0Ω, 0.125W, 0805
.,
RES., CHIP 5.6Ω, 1% 1206
.,
RES., CHIP 3.6Ω, 1% 1206
.,
RES., CHIP 33.2k, 0.1W, 1% 0603
.,
RES., CHIP 12.1k, 0.1W, 1% 0603
.,
I.C.,VOLT. REG.
MANUFACTURER/PART NUMBER
AVX, 06035A102KAT2A
AVX, 06035C103KAT2A
SANYO, 50ME270WX+T
SANYO, 16SEP330M+T
AVX, 1210YC226MAT2A
TAIYO YUDEN, EMK107BJ224MA
AVX, 12105C335MAT2A
MURATA, GRM188R71A225K
AVX, 12061A391KAT2A
AVX, 12061A182KAT2A
AVX, 06035C104KAT2A
AVX, 12065C105MAT2A
AVX, 1206ZC106MAT2A
AVX, 0603YC105MAT2A
DIODES, BAS16
DIODES INC., DFLS160
DIODES INC. B240A-13-F
DIODES INC. BZX84C5V1-7-F
TOKO, FDA1254-4R7M
VISHAY, Si7884BDP-T1-E3
VISHAY, Si4840BDY-T1-E3
VISHAY, SiR496DP-T1-GE3
VISHAY, CRCW060314K7FKEA
VISHAY, CRCW0603113KFKEA
VISHAY, CRCW06038K06FKEA
VISHAY, CRCW06035R60FKEA
Thin Film Tech., RL3720WT-R010-G-C
VISHAY, CRCW0603100RJNEA
VISHAY, CRCW060315R0FKEA
VISHAY, CRCW0603100KFKEA
VISHAY, CRCW060310R0JNEA
VISHAY, CRCW06031K24FKEA
Thin Film Tech., RL3720WT-R004-G-C
VISHAY, CRCW0603121K0FKEA
VISHAY, CRCW060310K0FKEA
VISHAY, CRCW08050000Z0EA
VISHAY, CRCW12065R60FNEA
VISHAY, CRCW12063R60FNEA
VISHAY, CRCW060333K2FKEA
VISHAY, CRCW060312K1FKEA
Linear Tech. Corp.LTC3789EGN
dc1523af
Required Circuit Components
4
DEMO MANUAL DC1523A
PARTS LIST
ITEM
42
43
44
45
46
47
48
49
50
51
52
53
54
55
QTY
0
1
0
0
0
0
0
4
7
1
2
2
4
4
REFERENCE
C3, C23, C26, C27 OPT
CIN2
CF1, C11, CF C7, C8 OPT
,
COUT2 OPT
Q6 OPT
Q7 OPT
R6, R12, R22, R27 OPT
TP1, TP2, TP3, TP7
TP4-TP6, TP8, TP10-TP12
JP1
JP2C, JP2B
XJP1, XJP2B
J1, J2, J3, J4
(STAND-OFF)
Dual N-CHAN., Si7948DP 60V
,
Dual N-CHAN., Si7958DP 40V
,
RES., OPT
TESTPOINT, TURRET, 0.061" PBF
TESTPOINT, TURRET, 0.094" PBF
3-PIN 0.079 SINGLE ROW HEADER
2-PIN 0.079 SINGLE ROW HEADER
SHUNT, 0.079" CENTER
CONNECTOR, BANANA JACK
STAND-OFF NYLON 0.25"
,
MILL-MAX, 2308-2-00-80-00-00-07-0
MILL-MAX, 2501-2-00-80-00-00-07-0
SAMTEC, TMM103-02-L-S
SAMTEC, TMM102-02-L-S
SAMTEC, 2SN-BK-G
KEYSTONE, 575-4
KEYSTONE, 8831(SNAP ON)
PART DESCRIPTION
CAP 1210
.,
CAP Alum, OPT
.,
CAP 0603
.,
MANUFACTURER/PART NUMBER
Additional Demo Board Circuit Components
Hardware for Demo Board Only
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