DC870A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 870A-A
HIGH EFFICIENCY MONOLITHIC SYNCHRONOUS BUCK REGULATOR
LTC3410
DESCRIPTION
Demonstration circuit 870A-A is a high efficiency,
high frequency buck converter, incorporating the
LTC3410 monolithic synchronous regulator. The
DC870 has an input voltage range of 2.25V to 5.5V,
and is capable of delivering up to 300mA of output
current. It has an output voltage range from 0.8V to
5V, and an operating frequency of 2.25MHz (allowing
the exclusive use of low profile surface mount components). In Burst Mode operation, which is the
mode of low load current operation offered by the
LTC3410, the DC supply current is typically only 26uA
at no load, and less than 1uA in shutdown The
DC870 is a very efficient circuit: up to 96%. These
features, plus the LTC3410 coming in a tiny, lowprofile 6-pin SC70 package, make the DC870 demo
board an ideal circuit for use in battery-powered,
hand-held applications.
Design files for this circuit board are available. Call
the LTC factory.
LTC and Burst Mode are trademarks of Linear Technology Corporation
Table 1.
Performance Summary (TA = 25°C)
PARAMETER
Minimum Input Voltage
CONDITION
VALUE
2.25V
Maximum Input Voltage
Output Voltage VOUT
Typical Output Ripple VOUT
Output Regulation
5.5V
VIN = 2.25V to 5.5V, IOUT = 0A to 0.3A
1.8V ±4%
VIN = 5V, IOUT = 0.3A (20 MHz BW)
20mVP–P
Line
±1%
Load
±1%
Nominal Switching Frequency
2.25 MHz
QUICK START PROCEDURE
The DC870A-A is easy to set up to evaluate the performance of the LTC3410. For proper measurement
equipment configuration, set up the circuit according
to the diagram in Figure 1. Before proceeding to test,
insert shunt on jumper JP1 into the off position, connecting the RUN pin to ground (GND), which shuts
down the circuit.
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.
Connect the input power supply and the load to the
board. Do not hot-plug Vin or increase Vin over
the rated maximum supply voltage of 5.5V, or the
part may be damaged. Refer to figure 1 for proper
measurement equipment setup.
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 870A-A
HIGH EFFICIENCY MONOLITHIC SYNCHRONOUS BUCK REGULATOR
2.
3.
4.
Apply 3.3V at Vin. Measure Vout; it should read
0V. If desired, one can measure the shutdown
supply current at this point. The supply current
will be approximately 1uA in shutdown.
Turn on the circuit by inserting the shunt in jumper
JP1 into the ON position. The output voltage
should be regulating. Measure Vout; it should
measure 1.8V +/- 2%.
Vary the input voltage from 2.25V to 5.5V and adjust the load current from 0 to 0.3A. Vout should
read 1.8V +/- 3%.
5.
Measure the output ripple voltage at any output
current level; it should measure less than 20mVAC.
6.
Observe the voltage waveform at the switch node
(one pin of the inductor). Verify the switching frequency is between 1.8MHz and 2.7MHz (T =
0.56us and 0.37us), and that the switch node
waveform is rectangular in shape.
TM
The Burst-Mode capability of the LTC3410 can be
observed now by reducing load current.
When finished, turn off the circuit by inserting the
shunt in jumper JP1 into the OFF position.
Figure 1. Proper Measurement Equipment Setup
2
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 870A-A
HIGH EFFICIENCY MONOLITHIC SYNCHRONOUS BUCK REGULATOR
Figure 2. Measuring Input or Output Ripple
Figure 3. Load Step Response
Vin = 3.3V, Vout = 1.8V, Iout Step = 0.2A
Trace 1: Output Voltage (50 mV/div AC)
Trace 2: Output Current (0.1A/div)
3
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 870A-A
HIGH EFFICIENCY MONOLITHIC SYNCHRONOUS BUCK REGULATOR
4
Bill Of Material
Demo Bd. # 870A-A
Linear Technology Corporation
LTC3410ESC6
1/18/2006
2:59 PM
Qty
Reference
Part Description
Manufacture / Part #
REQUIRED CIRCUIT COMPONENTS:
1
2
3
4
5
6
7
1
1
1
1
1
1
1
C1
C2
C4
L1
R2
R3
U1
1
2
1
1
C3
R1
CAP., X5R, 2.2uF, 6.3V, 10% 0603
CAP., X5R, 4.7uF, 6.3V, 20% 0603
CAP., C0G, 10pF, 50V, 5% 0402
INDUCTOR, 4.7uH, LQH32CN
RES., CHIP, 374K, 1/16W, 1% 0402
RES., CHIP, 301K, 1/16W, 1% 0402
IC.,LTC3410ESC6, SC70
Taiyo Yuden, JMK107BJ225KA
Taiyo Yuden, JMK107BJ475MA
AVX, 04025A100JAT2A
MURATA, LQH32CN4R7M53L
AAC, CR05-3743FM
Vishay CRCW0402301KFKTD
LINEAR TECH., LTC3410ESC6
ADDITIONAL DEMO BOARD CIRCUIT COMPONENTS:
CAP., X5R, 0.1uF, 6.3V, 10% 0402
RES., CHIP, 4.7M, 1/16W, 5%, 0402
Page 1 - of - 1
AVX, 04026D104KAT2A
AAC, CR05-475JM
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