Linear Technology DC1878A Quick setup guide

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dc1878af
DEMO MANUAL DC1878A
Description
LTC3789EGN
8V to 75VIN Buck/Boost
DC/DC Converter
Demonstration circuit 1878A features the LTC3789EGN,
a high efficiency switching step-up/down controller. The
input range has been extended to 75V by using a LTC4444-
5 MOSFET driver on the input side. The minimum input
voltage is 8V. The output voltage 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. L, LT, LTC, LTM, µModule, 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
An accurate output current limit provides support for bat-
tery charging. A wide input and output range with smooth
transfer function through all operating modes makes the
productidealforautomotive,telecomandbattery 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
(TA= 25°C)
PARAMETER CONDITIONS VALUE
Minimum Input Voltage 8V
Maximum Input Voltage 75V
Output Voltage VOUT Regulation VIN = 8V – 75V, IOUT = 0A – 5A 12V ± 2%
Maximum Continuous Output Current Some Airflow May Be Needed at High Input Voltage and
Continuous Full Load
5A
Default Operating Frequency R3 = 0Ω 200kHz
External Clock Synchronous Frequency Range 200kHz – 600kHz
Efficiency VIN = 8V to 75V, IOUT = 5A 90.5% to 97%. See Figures 3 and 6
Load Transient See Figure 5

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dc1878af
DEMO MANUAL DC1878A
Quick start proceDure
Demonstration circuit 1878A 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 8A
at 8V input voltage.
3. Place jumper in the following position:
JP1
RUN
ON
4. Turn on the power at the input. Increase VIN to between
8V and 75V. The circuit will start and the output voltage
will regulate at 12V ±2%. The current draw at no load is
typically 18mA to 37mA 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 high input voltage may
require some airflow.
Auxiliary Supply
The demo board DC1878A has a LTC3803 based flyback
converter to provide 8V/50mA bias voltage for LTC3789
and LTC4444-5. The snubber for the flyback primary wind-
ing provides a voltage that is above the input voltage. A
transistor Q9 is used to provide a small current source
to the top gate driver of LTC4444-5 so that 100% duty
cycle is possible.
If this current source is not used, for example if the flyback
auxiliary supply is replaced by an external 6V to 12Vsupply,
it is necessary to connect BOOST1 to 3.0V (add 3V Zener
diode D11, R11 = 1k, remove R16) and use a level shift
circuit (add D3 = BAS16, R12 = 1k, remove R6) between
TG1 and TINP (due to the 3.25V maximum threshold for
TINP). By setting BOOST1 to 3.0V, the LTC3789 will issue
narrow refresh pulses on BG1 which keeps the top gate
driver powered also in BOOST mode.
In addition, DC1878Ademoboard has layoutfor an optional
bias supply intended for a future monolithic high voltage
buck regulator. Additional information will be provided
when this part is released.

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dc1878af
DEMO MANUAL DC1878A
Figure 1. Proper Measurement Equipment Setup
Quick start proceDure

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dc1878af
DEMO MANUAL DC1878A
Quick start proceDure
Figure 2. Input Current at Full Load (12V at 5A Output)
Figure 3. Efficiency and Power Loss at Full Load. The Power Loss is Highest at High Input
Voltage Due to the Switching Losses and Drops as Input Voltage Decreases, Until the Inductor
Current Starts to Increase as the Circuit Enters Boost Mode Below 10V Input Voltage
INPUT VOLTAGE (V)
40302010 807060500
EFFICIENCY (%)
POWER LOSS (W)
100
98
94
96
92
90
86
88
84
8
7
5
6
4
3
1
2
0
PLOSS
η%
INPUT VOLTAGE (V)
40302010 807060500
CURRENT (A)
10
9
7
8
6
5
3
4
2
1
IOUT
0
IIN

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DEMO MANUAL DC1878A
Quick start proceDure
Figure 4. Output Ripple Voltage Measured Across COUT1
100mV

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DEMO MANUAL DC1878A
Quick start proceDure
Figure 5. Load Transient Response

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dc1878af
DEMO MANUAL DC1878A
Quick start proceDure
Figure 6. Efficiency at Various Input Voltages
LOAD (A)
4321 50
EFFICIENCY (%)
100
98
94
96
92
90
88
85
86
99
95
97
93
91
89
87
8V
12V
16V
24V
36V
48V
60V
72V
76V

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DEMO MANUAL DC1878A
Figure 7. Output Current Limit (The Easiest Way to
Do This Test Is with an Active Load in Voltage Mode)
Quick start proceDure
LOAD (A)
4321 650
VOUT (V)
14
12
8
10
6
4
2
0

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dc1878af
DEMO MANUAL DC1878A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
1 1 CC1 CAP, 0603 470pF 10% 50V NPO AVX 06035A471KAT
2 1 CC2 CAP, 0603 0.01µF 10% 50V X7R AVX 06035C103KAT2A
3 0 CF1, C31, C32, C37, CF CAP, 0603 OPTION OPTION
4 0 CIN1, COUT11, CIN11, COUT21, CIN21 CAP, OPTION OPTION
5 1 CIN2 CAP, 150µF 100V ELEC SUN ELEC. 100ME150AX
6 1 COUT1 CAP, 330µF 20% 16V OSCON SUN ELECT. 16SEP330M+T
7 0 COUT2 CAP, 330µF 20% 16V OSCON OPTION SUN ELECT. 16SEP330M+T OPTION
8 1 CSS CAP, 0603 4700pF 10% 50V X7R AVX 06035C472KAT2A
9 2 C1,C2 CAP, 1210 22µF 10% 25V X5R MURATA GRM32ER61E226KE15L
10 0 C3, C21, C23, C25, C27, C28 CAP, 1210 OPTION OPTION
11 1 C4 CAP, 0603 0.22µF 10% 25V X7R AVX 06033C224KAT2A
12 3 C5, C6, C9 CAP, 1210 2.2µF 10% 100V X7R MURATA GRM32ER72A225KA35L
13 0 C7, C8, C29, C30, C33 CAP, 1210 2.2µF 10% 100V X7R OPTION MURATA GRM32ER72A225KA35L OPTION
14 1 C10 CAP, 0603 4.7µF 20% 6.3V X5R TAIYO YUDEN JMK 107 BJ457MA-T
15 1 C11 CAP, 0603 33pF 10% 50V NPO AVX 06035A330KAT2A
16 0 C12, C13 CAP, 1206 OPTION OPTION
17 3 C14, C16, C26 CAP, 0603 0.1µF 10% 50V X7R AVX 06035C104KAT2A
18 1 C15 CAP, 0805 1µF 20% 16V X5R AVX 0805YD105MAT2A
19 1 C17 CAP, 0603 1nF 10% 50V COG AVX 06035A102KAT2A
20 2 C18, C20 CAP, 1206 10µF 20% 10V X7R AVX 1206ZC106MAT2A
21 2 C19, C24 CAP, 0603 1µF 20% 16V X7R AVX 0603YC105MAT2A
22 1 C22 CAP, 0603 0.22µF 20% 16V X7R TAIYO YUDEN EMK107BJ224MA
23 0 C34 CAP, 0603 0.1µF 10% 50V X7R OPTION AVX 06035C104KAT2A OPTION
24 0 C35 CAP, 0603 47nF 10% 25V X7R OPTION AVX 06033C473KAT2A OPTION
25 0 C36 CAP, 1210 47µF 10% 10V X7R OPTION MURATA GRM32ER71A476KE15L OPTION
26 3 D2, D9, D12 DIODE, SWITCHING, 200mW, SOT23 DIODES INC. BAS16
27 0 D3, D10, D11 DIODE, OPTION SOT-23 OPTION
28 2 D4, D14 DIODE, SWITCHING, 350mW, SOT23 DIODES INC. BAS21
29 1 D5 DIODE, SCHOTTKY DIODES INC. B1100
30 1 D6 DIODE, SCHOTTKY, SMA DIODES INC. B240A-13-F
31 1 D7 DIODE, SCHOTTKY DIODES INC. DFLS160
32 1 D8 DIODE, ZENER, 5.1V, SOT23 DIODES INC. BZX84C5V1-7-F
33 1 D13 DIODE, ZENER, 6.8V, SOT23 DIODES INC. BZX84C6V8
34 1 D15 DIODE, 1.0A HIGH VOLTAGE SCHOTTKY
BARRIER RECTIFIER
DIODES INC. DFLS1100
35 1 JP1 HEADER, SINGLE ROW, 3 PIN, 2mm SAMTEC TMM103-02-L-S
36 0 JP2 HEADER, SINGLE ROW, 3 PIN, 2mm
OPTION
SAMTEC TMM103-02-L-S OPTION
37 4 J1, J2, J3, J4 JACK, BANANA KEYSTONE 575-4
38 1 L1 IND, 19µH PULSE PA2050.193NL
39 0 L2 IND, 22µH OPTION TDK VLF10040T-220M2R5 OPTION
40 4 MH1, MH2, MH3, MH4 STANDOFF, SNAP ON KEYSTONE_8834

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dc1878af
DEMO MANUAL DC1878A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
41 1 Q1 XSTR, FDC2512 N-CHANNEL MOSFET FAIRCHILD FDC2512
42 1 Q2 XSTR, MOSFET N-CHANNEL 100V VISHAY SiR870DP
43 2 Q3, Q5 XSTR, MOSFET N-CHANNEL 20V VISHAY SiR496DP-T1-GE3
44 1 Q4 XSTR, MOSFET N-CHANNEL 100V VISHAY SiR882DP
45 1 Q6 XSTR, SMALL SIGNAL NPN SOT-23 DIODES INC. MMBTA42-7
46 0 Q8, Q13 XSTR, MOSFET N-CHANNEL 20V OPTION VISHAY SiR496DP-T1-GE3 OPTION
47 1 Q9 XSTR, SMALL SIGNAL PNP SOT-23 DIODES INC. MMBTA92-7
48 0 Q14, Q15 XSTR, MOSFET N-CHANNEL 100V OPTION VISHAY SiR882DP OPTION
49 1 RC RES, 0603 14.7kΩ 1% 1/10W VISHAY CRCW060314K7FKEA
50 1 RFB1 RES, 0603 113kΩ 1% 1/10W VISHAY CRCW0603113KFKEA
51 1 RFB2 RES, 0603 8.06kΩ 1% 1/10W VISHAY CRCW06038K06FKEA
52 1 R1 RES, 0805 5.6Ω 1% 1/10W VISHAY CRCW08055R60FKNEA
53 1 R2 RES, 3720 0.01Ω 2% 1W THIN FILM RECH. RL3720WT-R010-F
54 3 R3, R4, R44 RES, 0603 100Ω 5% 1/10W VISHAY CRCW0603100RJNEA
55 1 R5 RES, 0805 4.7Ω 1% 1/10W VISHAY CRCW08054R70FKNEA
56 8 R6, R11, R16, R21, R25, R27, R32, R50 RES, 0603 0Ω JUMPER VISHAY CRCW06030000Z0EA
57 3 R7, R15, R20 RES, 0603 100kΩ 1% 1/10W VISHAY CRCW0603100KFKEA
58 2 R8, R26 RES, 0603 10Ω 5% 1/10W VISHAY CRCW060310R0JNEA
59 2 R9, R10 RES, 0603 1kΩ 1% 1/10W VISHAY CRCW06031K00FKEA
60 0 R12, R19, R22, R23, R33-R36, R51 RES, 0603 OPTION OPTION
61 2 R13, R14 RES, 0603 154kΩ 1% 1/10W VISHAY CRCW0603154KFKEA
62 0 R17 RES, 0805 0Ω JUMPER OPTION VISHAY CRCW08050000Z0EA OPTION
63 1 R18 RES, 3720 0.012Ω 2% 1W THIN FILM TECH. RL3720WT-R012-F
64 1 R24 RES, 0603 10kΩ 1% 1/10W VISHAY CRCW060310K0FKEA
65 0 R28, R29 RES, 1206 OPTION OPTION
66 1 R30 RES, 1206 64.9kΩ 1% 1/10W VISHAY CRCW120664K9FKEA
67 1 R31 RES, 0603 12.1kΩ 1% 1/10W VISHAY CRCW060312K1FKEA
68 1 R37 RES, 0603 14kΩ 1% 1/10W VISHAY CRCW060314K0FKEA
69 1 R38 RES, 1206 220kΩ 5% 1/4W VISHAY CRCW1206220KJNEA
70 1 R39 RES, 1206 100kΩ 1% 1/10W VISHAY CRCW1206100KFKEA
71 1 R40 RES, 0603 22.1kΩ 1% 1/10W YAGEO RC0603FR-0722KIL
72 1 R41 RES, 0603 1.58kΩ 1% 1/10W VISHAY CRCW06031K58FKEA
73 1 R42 RES, 0603 10Ω 1% 1/8W VISHAY CRCW060310R0FKEA
74 1 R43 RES, 1206 0.30Ω 1% 1/8W IRC LR1206LF-01-R300-F
75 1 R45 RES, 0603 24.9kΩ 1% 1/10W NIC NRC06F2492TRF
76 2 R46, R47 RES, 0603 33.2kΩ 1% 1/10W VISHAY CRCW060333K2FKEA
77 1 R48 RES, 0603 5.6kΩ 1% 1/10W VISHAY CRCW06035K49FKEA
78 0 R49, R55, R56 RES, 0603 0Ω JUMPER OPTION VISHAY CRCW06030000Z0EA OPTION
79 0 R52 RES, 0603 2MΩ 1% 1/10W OPTION VISHAY CRCW06032M00FKEA OPTION
80 0 R53 RES, 0603 102kΩ 1% 1/10W OPTION VISHAY CRCW0603102KFKEA OPTION
81 0 R54 RES, 0603 11.3kΩ 1% 1/10W OPTION VISHAY CRCW060311K3FKEA OPTION
82 4 TP1, TP2, TP3, TP7 TURRET MILL-MAX 2308-2-00-80-00-00-07-0

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dc1878af
DEMO MANUAL DC1878A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
83 7 TP4, TP5, TP8, TP10, TP11-TP13 TURRET MILL-MAX 2501-2-00-80-00-00-07-0
84 1 T1 XFMR, LOW POWER FLYBACK TRANS PULSE PA0648NL
85 1 U1 IC, VOLT REG. LINEAR TECH. LTC3789EGN
86 1 U2 IC, HIGH VOLTAGE SYNCHRONOUS
N-CHANNEL MOSFET DRIVER
LINEAR TECH. LTC4444EMS8E-5
87 1 U3 IC, CONSTANT FREQ. CURRENT MODE
FLYBACK DC/DC CONTROLLER
LINEAR TECH. LTC3803ES6-5
88 0 U4 IC, STEP-DOWN CONVERTER, MSE16(12),
4mm ×3mm OPTION
LINEAR TECH. FUTURE PRODUCT
89 1 XJP1 SHUNT SAMTEC 2SN-BK-G
90 0 XJP2 SHUNT OPTION SAMTEC 2SN-BK-G OPTION

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dc1878af
DEMO MANUAL DC1878A
schematic Diagram
5 5
4 4
3 3
2 2
1 1
D D C C B B A A
CIRCUITRY ON THIS SIDE MUST CONNECT TO POWER GND GROUNDPLANE
CIRCUITRY ON THIS SIDE MUST CONNECT TO SIGNAL GND GROUNDPLANE
<------ ------>
8V
SHT 2
SHT 2
TG2 SW2
BG2 BG1
CS SW1
TG1
TG1 SW1 BG1 BG2 TG2 SW2 CS
VOS+
VOS+
VOUT
VIN
VOUT
INTVCC
VOUT
INTVCC
VOUT1
INTVCC
VIN
INTVCC
INTVCC
VAUX
VIN
VOUT1
B
BG2 TG2 SW2 TG1 SW1 BG1 CS
REVISION HISTORY
DESCRIPTIONDATEAPPROVEDECOREV
TAGE B.
PRODUTION
210/28/11
REVISION HISTORY
DESCRIPTIONDATEAPPROVEDECOREV
TAGE B.
PRODUTION
210/28/11
REVISION HISTORY
DESCRIPTIONDATEAPPROVEDECOREV
TAGE B.
PRODUTION
210/28/11
TECHNOLOGY
Tuesday, January 17, 2012
8V - 75V VIN BUCK-BOOST DC/DC
LTC3789EGN
DEMO CIRCUIT 1878A
CONVERTER
TECHNOLOGY
Tuesday, January 17, 2012
8V - 75V VIN BUCK-BOOST DC/DC
LTC3789EGN
DEMO CIRCUIT 1878A
CONVERTER
TECHNOLOGY
Tuesday, January 17, 2012
8V - 75V VIN BUCK-BOOST DC/DC
LTC3789EGN
DEMO CIRCUIT 1878A
CONVERTER
R33OPTR33OPT
R11
0
R11
0
D4
BAS21
D4
BAS21
31
U2
LTC4444EMS8E-5
U2
LTC4444EMS8E-5
BG
4
NC
5
TS
8
TINP
1
BINP
2
VCC
3
BOOST
6
TG
7
GND
9
TP7
GND
TP7
GND
R2610R2610
TP13
VAUX
TP13
VAUX
C10
4.7uF
C10
C6 2.2uF 100V 1210 C6 2.2uF 100V 1210
R50
0
R50
0
R29
OPT 1206
R29
OPT 1206
C22
0.22uF
16V
C22
0.22uF
16V
Q3
SiR496DP
Q3
SiR496DP
TP12
EXTVCC
TP12
EXTVCC
CC2
0.01uF
CC2
0.01uF
D9
BAS16
D9
BAS16
3 1
C7 OPT 1210 C7 OPT 1210
R9 1k 1% R9 1k 1%
R25
0
R25
0
R14
154k
1%
R14
154k
1%
R101k 1% R101k 1%
CF
OPT
CF
OPT
R8 10 R8 10
C13 OPT
1206
C13 OPT
1206
JP1
ON
OFF
RUN
JP1
ON
OFF
RUN
1 3 2
RC
14.7k 1%
RC
14.7k 1%
C1 22uF 25V 1210 C1 22uF 25V 1210
R28 OPT
1206
R28 OPT
1206
R1 5.6
0805
R1 5.6
0805
C23 OPT 1210 C23 OPT 1210
C18
10uF1206
C18
10uF1206
J3 VIN
8V - 75V
J3 VIN
8V - 75V
CSS 4700pF CSS 4700pF
R15 100k 1%R15 100k 1%
C3 OPT 1210 C3 OPT 1210
D7
DFLS160
D7
DFLS160
D6 B240A D6 B240A
R32
0
R32
0
+
COUT1 330uF 16V
+
COUT1 330uF 16V
C11
33pF
C11
33pF
+
CIN1 OPT
+
CIN1 OPT
C29 OPT 1210 C29 OPT 1210
D5
B1100
D5
B1100
C5 2.2uF 100V 1210 C5 2.2uF 100V 1210
D8
BZX84C5V1
D8
BZX84C5V1
RFB2
8.06K
RFB2
8.06K
R7
100k
R7
100k
TP8
INTVCC
TP8
INTVCC
R2
0.010
2%
R2
0.010
2%
TP3VIN+ TP3VIN+
C4
0.22uF
16V
C4
0.22uF
16V
R18 0.012 2% R18 0.012 2%
+
CIN2 150uF
100V
+
CIN2 150uF
100V
C21 OPT 1210 C21 OPT 1210
J4 GND J4 GND
C30 OPT 1210 C30 OPT 1210
Q5
SiR496DP
Q5
SiR496DP
Q4
SiR882DP
Q4
SiR882DP
TP5
SS
TP5
SS
L1
19uH
L1
19uH
D3
OPT
D3
OPT
3 1
R5
4.7
0805 R5
4.7
0805
C28 OPT 1210 C28 OPT 1210
R21
0
R21
0
C16
0.1uF
C16
0.1uF
R30
64.9k
1206
R30
64.9k
1206
J1
VOUT
12V / 5A MAX
J1
VOUT
12V / 5A MAX
C12 OPT 1206 C12 OPT 1206
R6 0R6 0
D11
OPT
D11
OPT
TP11
SGND
TP11
SGND
C25 OPT 1210 C25 OPT 1210
R3 100 R3 100
TP2
VOS+
TP2
VOS+
R35
OPT
R35
OPT
CC1 470pF CC1 470pF
R22
OPT
R22
OPT
CF1
OPT
CF1
OPT
C15
1uF
16V 0805
C15
1uF
16V 0805
TP4
PGOOD
TP4
PGOOD
C9 2.2uF 100V
1210
C9 2.2uF 100V
1210
R20 100k 1%R20 100k 1%
R36
OPT
R36
OPT
R19 OPT R19 OPT
R13
154k
1%
R13
154k
1%
U1
LTC3789EGN
U1
LTC3789EGN
VFB
1
SS
2
SENSE1+
3
SENSE1-
4
ITH
5
SGND
6
MODE/PLLIN
7
FREQ
8
RUN
9
VINSNS
10
VOUTSNS
11
ILIM
12
IOSENSE+
13
IOSENSE-
14
NC
15
SW2
16
TG2
17
BOOST2
18
BG2
19
EXTVCC
20
INTVCC
21
VIN
22
PGND1
24
BOOST1
25
SW1
27
PGOOD
28
TG1
26
BG1
23
C2
22uF
25V
1210
C2
22uF
25V
1210
R24
10K
R24
10K
D2
BAS16
D2
BAS16
3 1
+
COUT2 330uF 16V
OPT
+
COUT2 330uF 16V
OPT
D10
OPT
D10
OPT
RFB1
113K
RFB1
113K
C8 OPT 1210 C8 OPT 1210
C24
1uF
C24
1uF
J2 GND J2 GND
R4 100R4 100
TP1
VOS-
TP1
VOS-
R12
OPT
R12
OPT
R34 OPT R34 OPT
R31
12.1K
R31
12.1K
TP10
PLLIN
TP10
PLLIN
C27 OPT 1210 C27 OPT 1210
Q2
SiR870DP
Q2
SiR870DP
C14
0.1uF
C14
0.1uF

13
dc1878af
DEMO MANUAL DC1878A
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
schematic Diagram
5 5
4 4
3 3
2 2
1 1
D D C C B B A A
CLAMPING SNUBBER/ 400uA SUPPLY
1206
1206
1206
AUXILIARY SUPPLY
8V / 50mA
SHT 1
SHT 1
SHT 1
OPTIONAL PARTS
10V
1210
OPTIONAL BIAS SUPPY
TG1 BG1
SW2SW1 TG2 BG2
CS
VAUX1
VAUX1
VIN
VAUX
VIN
VIN
VIN
VOUT1
VINVIN
VAUX
B
CS TG1 SW1 BG1
TG2 SW2 BG2
TECHNOLOGY
Thursday, December 08, 2011
8V - 75V VIN BUCK-BOOST DC/DC
LTC3789EGN
DEMO CIRCUIT 1878A
CONVERTER
TECHNOLOGY
Thursday, December 08, 2011
8V - 75V VIN BUCK-BOOST DC/DC
LTC3789EGN
DEMO CIRCUIT 1878A
CONVERTER
TECHNOLOGY
Thursday, December 08, 2011
8V - 75V VIN BUCK-BOOST DC/DC
LTC3789EGN
DEMO CIRCUIT 1878A
CONVERTER
C35 47nF C35 47nF
R37
14k1%
R37
14k1%
L2
22uH
TDK VLF10040
L2
22uH
TDK VLF10040
R51
OPT
R51
OPT
Q1 FDC2512 Q1 FDC2512
2
1
3
4
5
6
Q8
SiR496DP
Q8
SiR496DP
T1
PA0648NL
T1
PA0648NL
8
57
1 2
4
R52 2M
1%
R52 2M
1%
D14 BAS21 D14 BAS21
3 1
Q13
SiR496DP
Q13
SiR496DP
U4
FUTURE LTCXXXX
U4
SW
1
NC
2
VIN
3
NC
4
FBO
5
VPRG1
7
VPRG2
6
GND
8
VFB
9
SS
10
ISET
11
OV
12
NC
13
RUN
14
NC
15
GND
16
GND
17
R45
24.9k 1%
R45
24.9k 1%
C26
0.1uF
C26
0.1uF
Q14
SiR870DP
Q14
SiR870DP C34
0.1uF
C34
0.1uF
Q6 MMBTA42-7 Q6 MMBTA42-7
R46
33.2k
1%
R46
33.2k
1%
R17
OPT
0805
R17
OPT
0805
R39
100k 1%
R39
100k 1%
Q15
SiR882DP
Q15
SiR882DP
R16
0
R16
0
R53 102k
1%
R53 102k
1%
R47
33.2k 1%
R47
33.2k 1%
R48
5.6k 1%
R48
5.6k 1%
R55
0
R55
0
C31
OPT
C31
OPT
R38 220k R38 220k
D13
BZX84C6V8
D13
BZX84C6V8
R49 0 R49 0
C37 OPT C37 OPT
Q9
MMBTA92-7
Q9
MMBTA92-7
U3
LTC3803ES6-5
U3
LTC3803ES6-5
GND
2
ITH/RUN
1
VFB=0.8V
3
VCC
5
G
6
SNS
4
C19
1uF 16V
C19
1uF 16V
D15
DFLS1100
D15
DFLS1100
R43 0.30
1%
R43 0.30
1%
C36 47uF C36 47uF
R40
22.1k1%
R40
22.1k1%
R42101%R42101%
C33 2.2uF 100V 1210 C33 2.2uF 100V 1210
D12 BAS16 D12 BAS16
3 1
R44 100 R44 100
R41
1.58k1%
R41
1.58k1%
JP2
ON OFF BIAS RUN
JP2
ON OFF BIAS RUN
1
3
2
R23
OPT
R23
OPT
C20 10uF 10V
1206
C20 10uF 10V
1206
R54
11.3k 1%
R54
11.3k 1%
R56
0
R56
0
C17
1000pF
C17
1000pF
R27
0
R27
0
C32 OPT C32 OPT

14
dc1878af
DEMO MANUAL DC1878A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2012
LT 0312 • PRINTED IN USA
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 applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation

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