DEMO MANUAL DC1737A
LTC3863
Low I
Q
Inverting
DC/DC Converter
DESCRIPTION
Demonstration circuit 1737A is a current-mode inverting
DC/DC converter featuring the
LTC
®
3863.
The board operates from an input range of 4.5V to 16V,
and provides a –5.2V, 1.7A output or a –12V, 1A output
(jumper selectable). It operates at 400kHz and may be
synchronized to an external clock. A soft-start feature
controls output voltage slew rate at start-up, reducing
current surge and voltage overshoot. Burst Mode
®
opera-
tion that improves efficiency at light loads can be enabled
with a jumper. A power good output signal is provided.
The demonstration board has options for larger MOSFET
and diode packages on the back of the board for higher
output current requirements.
This board is suitable for a wide range of automotive,
telecom, industrial, and other applications. The LTC3863
is available in small 12-pin thermally enhanced MSOP and
DFN Packages. For other output requirements, see the
LTC3863 data sheet or contact the LTC factory.
Design files for this circuit board are available at
http://www.linear.com/demo
L,
LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
PERFORMANCE SUMMARY
SYMBOL
V
IN
V
OUT
I
OUT
f
SW
V
OUT P-P
V
REG
P
OUT
/P
IN
PARAMETER
Input Supply Range
Output Voltage
Output Current Range, Continuous
Switching (Clock) Frequency
Output Ripple
Output Regulation
Efficiency (See Figure 3)
Approximate Size
Free Air
Specifications are at T
A
= 25°C
MIN
4.5
–5.2V/–12V
0
400
30
±0.1
89.3
0.9
×
0.8
×
0.18
–1.7/1.0
TYP
MAX
16
UNITS
V
V
A
kHz
mV
P-P
%
%
Inches
CONDITIONS
V
IN
= 12V, V
OUT
= –12V, I
OUT
= 1A (20MHz BW)
Line and Load (4.5V
IN
to 16V
IN
, –12V
OUT
, 0A to 1A Out)
V
IN
= 12V, V
OUT
= –12V, I
OUT
= 1A
Component Area
×
Top Component Height
dc1737af
1
DEMO MANUAL DC1737A
QUICK START PROCEDURE
Demonstration circuit 1737 is easy to set up to evaluate
the performance of the LTC3863. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
Note:
When measuring the output voltage ripple, care must
be taken to avoid a long ground lead on the oscilloscope
probe. Measure the output voltage ripple by touching the
probe tip and ground ring directly across the last output
capacitor as shown in Figure 1.
1. Set an input power supply that is capable of 4.5V to
16V to 5V. Then turn off the supply.
2. With power off, connect the supply to the input terminals
+VIN and –VIN.
a. Input voltages lower than 4.5V can keep the converter
from turning on due to the undervoltage lockout
feature of the LTC3863.
b. If efficiency measurements are desired, an ammeter
capable of measuring 2A DC or a resistor shunt can
be put in series with the input supply in order to
measure the DC1737A’s input current.
c. A voltmeter with a capability of measuring at least
16V can be placed across the input terminals in order
to get an accurate input voltage measurement.
3. Turn on the power at the input.
Note:
Make sure that the input voltage never exceeds 16V.
4. Check for the proper output voltage of –5.2V. Turn off
the power at the input.
2
+
+
V
IN
–
V
IN
–
V
+
–
+
V
V
OUT
LOAD
+
A
I
IN
–
–
A
I
OUT
+
Figure 1. Proper Measurement Equipment Setup
dc1737af
DEMO MANUAL DC1737A
QUICK START PROCEDURE
5. Once the proper output voltage is established, connect
a variable load capable of sinking 1.7A at 5.2V to the
output terminals +VOUT and –VOUT. Set the current
for 0A.
a. If efficiency measurements are desired, an ammeter
or a resistor shunt that is capable of handling 1.7A
DC can be put in series with the output load in order
to measure the DC1737A’s output current.
b. A voltmeter with a capability of measuring at least 12V
can be placed across the output terminals in order
to get an accurate output voltage measurement.
90
85
EFFICIENCY (%)
80
V
IN
= 12V
75
V
IN
= 5V
6. Turn on the power at the input.
Note:
If there is no output, temporarily disconnect the load
to make sure that the load is not set too high.
7. Once the proper output voltage is again established,
adjust the load and/or input within the operating range
and observe the output voltage regulation, ripple volt-
age, efficiency and other desired parameters.
8. Remove the VOUT jumper to observe operation at
–12V
OUT
up to 1A.
90
85
V
IN
= 5V
EFFICIENCY (%)
80
V
IN
= 12V
75
70
70
65
0.01
0.1
I
OUT
(A)
1
65
0.01
0.1
I
OUT
(A)
1
Figure 2. –12V
OUT
Efficiency with Burst Mode Operation
at Light Loads
Figure 3. –5.2V
OUT
Efficiency with Burst Mode Operation
at Light Loads
Figure 4. Output Ripple at 12V
IN
, –12V
OUT
and 1A Out
(50mV, 2µs/Div, 20MHz)
Figure 5. Transient Response Waveform at 12V
IN
, –12V
OUT
and 0.5A to 1A to 0.5A Out (0.5A, 100mV, 10µs/Div)
dc1737af
3
DEMO MANUAL DC1737A
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
QTY
1
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
1
2
7
2
1
4
3
4
REFERENCE
CIN1
CIN2, CIN3
COUT1, COUT2
COUT3, COUT5
COUT4
C1
C2
C3
C5
C6
C7
C8
D1
L1
Q1
R1
R2
R3
R5
R7
R8
R9
R11
U1
COUT6
C4
R4
R6, R10
E1, E2, E3, E4, E5, E6, E7
JP1, JP3
JP2
J1, J2, J3, J4
XJP1, XJP2, XJP3
MTGS AT 4 CORNERS
PART DESCRIPTION
Cap., SMT, 100µF, 20V, SVP OSCON
CAP.,X7R, 10µF, 25V, 20%, 1210
CAP.,X7R, 33µF, 16V, 20%, 1812
CAP.,POSCAP, 150µF, 16V 7343
CAP.,X7R, 1µF, 16V, 10%, 0603
Cap., NPO, 100pF, 50V, 10%, 0603
Cap., X7R, 27nF 25V, 10%, 0603
Cap., NPO, 390pF, 25V, 1%, 0603
Cap., X7R, 0.47µF, 16V, 20%, 0603
Cap., X7R, 0.1µF, 16V, 20%, 0603
Cap., X7R, 0.1µF, 100V, 20%, 0805
CAP., NPO, 68pF, 50V, 5%, 0603
DIODE, PDS540, POWERDI5-2PIN
IND, 10uH, 20%, D104C
TRANSISTOR, SI7129DN, PWRPAK1212-8
RES., CHIP, 61.9k, 1/16W, 1% , 0603
RES., CHIP, 14.7k, 1/16W, 1% , 0603
RES., CHIP, 80.6k, 1/16W, 1% , 0603
RES., CHIP, 523k, 1/16W, 1% , 0603
RES., 0.016 1/2W 1% 2010
RES., CHIP, 100k, 1/16W, 1% , 0603
RES., CHIP, 698k, 1/10W, 1% , 0603
RES., CHIP, 45.3k, 1/16W, 1% , 0603
IC, LTC3863EMSE, MSE12
CAP., OPT KE0
CAP., OPT 0603
RES., OPT 0603
RES., CHIP, 0Ω, 1/16W, 0603
TESTPOINT, TURRET, .090” pbf
JMP, 0.079 SINGLE ROW HEADER, 3-PIN
JMP, 0.079 DOUBLE ROW HEADER, 6-PIN
CONN, BANANA JACK
SHUNT, 0.079" CENTER
STAND-OFF, SNAP ON NYLON 0.50" tall
MANUFACTURER/PART NUMBER
SANYO, 20SVP100M
TDK, C3225X7R1E106M
TDK, C4532X7R1C336M
PANASONIC, 16TQC150MYF
AVX, 0603YC105KAT2A
AVX, 06035A101kAT1A
AVX, 06033C273KAT
AVX, 06033A391FAT2A
AVX, 0603YC474MAT2A
AVX, 0603YC104MAT2A
TDK, C2012X7R2A104M
AVX, 06035A680JAT2A
DIODES INC, PDS540-13
TOKO, 919AS-100M=P3
VISHAY, Si7129DN-T1-GE3
VISHAY, CRCW060361K9FKED
VISHAY, CRCW060314K7FKED
VISHAY, CRCW060380K6FKED
VISHAY, CRCW0603523KFKED
VISHAY, WSL2010R0160FEA
VISHAY, CRCW0603100KFKED
VISHAY, CRCW0603698KFKED
VISHAY, CRCW060345K3FKED
LINEAR TECH.CORP. LTC3863EMSE
OPT
OPT
OPT
VISHAY, CRCW06030000Z0ED
MILL-MAX, 2501-2-00-80-00-00-07-0
SULLINS, NRPN031PAEN-RC
SULLINS, NRPN062PAEN-RC
KEYSTONE 575-4
SAMTEC, 2SN-BK-G
KEYSTONE, 8833(SNAP ON)
Required Circuit Components
Additional Demo Board Circuit Components
Hardware For Demo Board Only
dc1737af
4
DEMO MANUAL DC1737A
SCHEMATIC DIAGRAM
dc1737af
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.
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