DC1106A - Demo Manual

DEMO CIRCUIT 1106
QUICK STARTLT3570
GUIDE
LT3570
1.5A Buck Converter, 1.5A Boost Converter, and LDO
Controller
DESCRIPTION
Demonstration circuit 1106 is a 1.5A Buck Converter,
1.5A Boost Converter, and LDO Controller featuring the
LT3570. The Buck is designed to convert a 4V to 36V
source to 3.3V at 1A. The LDO is powered from the output of the Buck and converts it to 2.5V at 100mA. The
Boost converts a 3.3V-10V source to 12V at 275mA.
DC1106 was designed to switch at 500KHz.
In the DC1106 default setting, the Buck and Boost converters run from separate sources to allow for full input
variation for the Buck. To facilitate other input options,
there are two placeholders on the back of the board, R1
and R2. Installing a jumper at R1, allows the Boost output to power the Buck. Installing a jumper at R2, allows
both, the Boost and the Buck to be powered from the
same source.
The LT3570 features programmable switching frequency,
synchronization, external compensation, independent
soft-start for each converter. This circuit is intended for
space-conscious applications such as Cable Satellite Settop Boxes, Automotive Systems, Telecom Systems “Dying Gasp” Systems and TFT LCD Displays.
The LT3570 datasheet gives a complete description of
the part, operation and application information. The datasheet must be read in conjunction with this quick start
guide for working on or modifying the demo circuit
1106.
Design files for this circuit board are available. Call
the LTC factory.
L, LTC, LTM, LT are registered trademarks of Linear Technology Corporation.
Since the input to the Buck powers the internal oscillator,
it needs to be on for the Boost to switch.
PERFORMANCE SUMMARY FOR DC1106A Specifications are at TA = 25°C
SYMBOL
VIN BUCK
VIN BOOST
VOUT BUCK
VOUT BOOST
VOUT LDO
3.3V RIPPLE
12V RIPPLE
2.5V RIPPLE
EFFICIENCY
PARAMETER
Input Supply Range
Input Supply Range
Output Voltage Range
Output Voltage Range
Output Voltage Range
CONDITIONS
VIN = 4V-36V, ILOAD = 1A
VIN = 3.3V-10V, ILOAD = 275mA
ILOAD = 100mA
VIN =4V, ILOAD = 1A
VIN = 12V, ILOAD = 275mA
ILOAD = 100mA
Both input sources at 5V, Loads: 3.3V = 1A, 12V
= 275mA, 2.5V = 100mA
MIN
4
3.3
3.2
11.64
2.425
TYP
3.3
12
2.5
20
150
10
87
MAX
36
10
3.4
12.36
2.575
UNITS
V
V
V
V
V
mV
mV
mV
%
1
LT3570
QUICK START PROCEDURE
Demonstration circuit 1106 is easy to set up to evaluate
the performance of the LT3570. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
NOTE. When measuring the input or output voltage ripple, care must be
taken to avoid a long ground lead on the oscilloscope probe. Measure the
input or output voltage ripple by touching the probe tip directly across the
Vin or Vout and GND terminals. See Figure 2 for proper scope probe
technique.
1. Place jumpers in the following positions:
JP1, JP2, JP3 On
2. With power off, connect the input power supplies to
Vin and GND.
3. Turn on the power at the input.
Check for the proper output voltages. 3.3V = 3.2 to 3.4, 12Vout = 11.64V to
12.36V, and 2.5V = 2.425V to 2.575V.
NOTE. If there is no output, temporarily disconnect the load to make sure
that the load is not set too high.
4. Once the proper output voltages are established,
adjust the loads within the operating range and observe the output voltage regulation, ripple voltage,
efficiency and other parameters.
2
LT3570
Figure 1. Proper Measurement Equipment Setup
GND
VIN
Figure 2. Measuring Input or Output Ripple
3
C1
2.2uF
X7R
50V
C4
10uF
16V
[1] DO NOT STUFF.
ON
2.5V
1
ON
3.3V
1
ON
12V
1
R3 143K 1%
NOTES: UNLESS OTHERWISE SPECIFIED,
1uF
C12
C2
4.7uF
16V
VIN_BOOST
VIN_BUCK
TP11
TP5
TP3
TP1
TP4
TP8
SYNC
GND
[email protected]
GND
3.3V - 10V
VIN BOOST
GND
4V - 36V
OFF
3
JP3
OFF
R11 100K
OPT
C14
100K
R9 100K
JP2
3
R12
R7 100K
DFLS120
2
R15
22K
R2 OPT [1]
R1 OPT [1]
100nF
C9
SYNC
SHDN3
SHDN2
SHDN1
FB1
SW1
1nF
C8
14
13
12
11
10
4
U1
LT3570EUF
OFF
3
JP1
R4
10K
1%
1
D2
CDRH6D28NP-100
10uH
L1
7
IN1
VC1
9
TP2
2
FB2
SW2
BOOST
18
20
21
19
3
24
CHECKED
05/10/06
DATE
OPT
DFLS140
1
D3
2
TP6
GND
SCALE: NONE
DWG NO
SHEET
DC1106A
1
OF
1
REV
2
APPROVED
[email protected]
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
Fax: (408)434-0507
1uF TP9
2.2uF
TP7
C15
TECHNOLOGY
[email protected]
1uF TP10
GND
C11
DATE
05/14/08
C6
Q1
FMMT618
FILENAME: 1106A-2.DSN
SIZE CAGE CODE
Custom
1
PROTO
C5
22uF
6.3V
REVISION HISTORY
DESCRIPTION
SCH, LT3570EUF, DC/DC BOOST, BUCK AND
LDO CONVERTER
10.2K 1%
R10
R8 22.1K 1%
TITLE
R6 10.2K 1%
C13
L2 10uH
2
REV
CDRH6D28NP-100
ECO
R5 32.4K 1%
100nF
Monday, August 04, 2008
DESIGNER
ENGINEER
APPROVED
APPROVALS
DRAWN MEI
DO NOT SCALE DRAWING
R14
22K
1nF
C7
C3
CMDSH-3
D1
CONTRACT NO.
R13
44.2K
1%
VC2
FB3
NP_DRIVE
R16
0
VIN_BUCK
THIRD ANGLE PROJECTION
100nF
C10
22
UNLESS OTHERWISE SPECIFIED
DIMENSIONS ARE IN INCHES
TOLERANCE ON ANGLE - - 2 PLACES - - - 3 PLACES - - INTERPRET DIM AND TOL
PER ASME Y 14.5M -1994
SS1
8
1
IN2
SS2
17
IN2
GND
5
2
1
VIN BUCK
GND
6
23
BIAS
RT
IN3
GND
16
2
2
2
GND
25
Figure 3. Schematic
15
3
4
2
This circuit is proprietary to Linear Technology and s upplied
for use with Linear Technology parts .
Customer Notice:Linear Technology has m ade a bes t effort to
design a circuit that m eets custom er-s upplied s pecifications;
however, it rem ains the cus tom er's respons ibility to verify proper
and reliable operation in the actual application, Com ponent
s ubs titution and printed circuit board layout m ay s ignificantly
affect circuit perform ance or reliability. Contact Linear
Applications Engineering for ass is tance.
LT3570
Similar pages