DC683A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC683
1.2MHZ BOOST DC/DC CONVERTER IN THINSOT WITH 2A SWITCH
LT1935ES5
DESCRIPTION
Demonstration circuit DC683 features LT1935
1.2MHz boost dc/dc converter with 2A switch. The
circuit in DC683 is designed to generate 12V output from a 3.3V to 5.5V input voltage range. The
maximum output current is listed on the DC683
silkscreen along with the input voltage range.
The boost converter circuit is enabled using JP1.
Placing the jumper to “OFF” activates the SHDN
pin of the boost converter. Jumper to “ON” en-
ables the boost converter and will bring the output
up to 12V. The SHDN pin is also accessible via
J5 (turret).
Design files for this circuit board are available.
Call the LTC factory.
________________________________________________
LT is a trademark of Linear Technology Corporation
Table 1. Performance Summary (TA = 25°C unless otherwise noted)
PARAMETER FOR BOOST CONVERTER
CONDITION
VALUE
Minimum Input Voltage
For DC683 (IC datasheet spec. 2.3V)
3.3V
Maximum Input Voltage
For DC683 (IC datasheet spec. 16V)
5V
Maximum Output Current
12V output with 5V input
600mA
Typical Efficiency
5V input to 12V output with
200mA~600mA load
86%
Output voltage ripple
5V input to 12V output with 600mA load
75mV
Switching frequency
5V input to 12V output with 600mA load
1.2MHz
QUICK START PROCEDURE
Demonstration circuit 683 is easy to set up to
evaluate the performance of the LT1935. Refer
to Figure 1 for proper measurement equipment
setup and follow the procedure below:
1. With power off, connect the input power
supply to Vin and GND. Make sure JP1
is set to “ON”.
2. Set the input supply between 3.3V to 5V.
Turn on the power at the input and observe the output voltage across VOUT
and GND. The output voltage should
read ≅ 12V.
3. Turn on the load (follow the chart on the
demo board silkscreen for input voltage
and output current, 400mA maximum current with 3.3V input and 600mA maximum current with 5V input voltage). The
output voltage should be regulating to
≅ 12V under varying load conditions.
4. Test the SHDN function by placing the
jumper JP1 to “OFF”. The LT1935 should
stop switching and the output voltage
should read ≅ 0.3V below the input voltage. Enable the boost converter by placing the jumper (J1) back to “ON.” The
output should now read ≅ 12V.
5. Check the output ripple using the oscilloscope (refer to figure 2). The output ripple should not be greater than 100mV.
Also check the switching frequency, it
should be ≅ 1.2MHz.
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC683
1.2MHZ BOOST DC/DC CONVERTER IN THINSOT WITH 2A SWITCH
Figure 1. Proper Measurement Equipment Setup
Figure2. Measuring Input or Output Ripple
2
5
D
4
3
2
This circuit is proprietary to Linear Technology and supplied
for use with Linear Technology parts.
Customer Notice:Linear Technology has made a best effort to
design a circuit that meets customer-supplied specifications;
however, it remains the customers responsibility to verify proper
and reliable operation in the actual application, Component
substitution and printed circuit board layout may significantly
affect circuit performance or reliability. Contact Linear
Applications Engineering for assistance.
ECO
2
OFF
1
R3
SHDN
J5
4 SHDN
C3
10K
12V [1]
VOUT
UPS120
0.1uF
LT1935ES5
SW 1
2 JP1
U1
GND
0805
ON
VOUT
APPROVED
01/26/04
D1 1A
1
C2
POWERMITE
J3
10uF
R2
C4
86.6K
10pF
0603
0603
1206
C
FB 3
R1
10K
2
10V
C
3
VIN 5
4.7uF
DATE
PROTO
3.3uH
TDK SLF7028T-3R3M1R6
C1
DESCRIPTION
D
VIN
J1
REV
2
L1
3.3V-5V
1
REVISION HISTORY
0603
GND
GND
J4
J2
B
B
[1]
VIN
VOUT
3.3V
12V @ 400mA
5V
12V @ 600mA
CONTRACT NO.
APPROVALS
DRAWN
MEI
CHECKED
A
DATE
05/01/03
TECHNOLOGY
TITLE
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
Fax: (408)434-0507
SCH, LT1935ES5 BOOST CONVERTER
A
APPROVED
ENGINEER
DESIGNER
Friday, February 06, 2004
5
4
3
SIZE CAGE CODE
SCALE:
DWG NO
FILENAME: 683A-2.DSN
2
REV
DC683A
SHEET
2
1
1
OF
1
Linear Technology Corporation
LT1935ES5
Item
1
2
3
4
5
6
7
8
9
10
11
12
Qty
1
1
1
1
1
1
5
1
1
1
1
1
Ref
C1
C2
C3
C4
D1
JP1
J1,J2,J3,J4,J5
L1
R1
R2
R3
U1
DC683A Rev 2
6/20/2005
Parts List
Desc
CAP, X7R 4.7uF 10V 20% 0805
CAP, X7R 10uF 16V 20% 1206
CAP, X7R 0.1uF 10V 20% 0603
CAP, COG 10pF 50V 5% 0603
DIODE,SCHOTTKY 20V 1A
HEADER,3PIN, 2mm
TURRET
IND, 3.3uH
RES, 10K OHMS 1% 1/16W 0603
RES, 86.6KK OHMS 1% 1/16W 0603
RES, 10K OHMS 5% 1/16W 0603
IC, LT1935ES5
1 of 1
Manufacturer / Part #
TDK C2012X7R1A475M
TDK C3216X7R1C106M
AVX 0603ZC104MAT
AVX 06035A100JAT2A
MICROSEMI UPS120
COMM CON 2802S-03G2
MILL-MAX 2501-2
TDK SLF7028T-3R3M1R6
AAC CR16-1002FM
AAC CR16-8662FM
AAC CR16-103JM
LINEAR TECH. LT1935ES5
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