DC886A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 886
300mA VERY LOW DROPOUT LINEAR REGULATOR
LTC3035
DESCRIPTION
Demonstration circuit 886 is an ultra-low input voltage
and dropout voltage supply using the LTC3035 linear
regulator, which comes in a very small 8-pin DFN package. The DC886 has an input voltage range from 1.7V to
5.5V, an output voltage range between 0.4V and 3.6V,
and is capable of delivering 300mA of output current.
Due to the 0.4V reference of the LTC3035, the DC886 is
capable of supplying power to very low voltage applications, such as a (relatively) high current voltage refer-
ences. The DC886 comes assembled with small ceramic
capacitors – 1uF – to demonstrate the LTC3035 maintaining stability with ceramic output capacitors.
Design files for this circuit board are available. Call
the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Table 1.
Performance Summary (TA = 25°C)
PARAMETER
Minimum Input Voltage
CONDITION
VALUE
1.7V
Maximum Input Voltage
Output Voltage VOUT
Typical Dropout Voltage
Output Regulation
5.5V
VIN = 1.7V to 5.5V, IOUT = 0A to 300mA
1.8V ±3%
VIN = 1.7V, IOUT = 300mA
45mV
Line
±0.5%
Load
±0.5%
QUICK START PROCEDURE
The DC886 demonstration board is easy to set up to
evaluate the performance of the LTC3035. For proper
measurement equipment configuration, set up the
circuit according to the diagram in Figure 1. Before
proceeding to test, insert jumper JP5 shunt into the
off (lower) position, connecting the RUN pin to
ground (GND), which shuts down the circuit.
NOTE: When measuring the input or output ripple or
noise voltage, care must be taken to avoid a long
ground lead on the oscilloscope probe. Measure the
voltages 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 the
proper measurement equipment setup.
2.
Select any of the output voltages by inserting a
shunt into that output voltage jumper position.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 886
300mA VERY LOW DROPOUT LINEAR REGULATOR
3.
Apply 5V 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.
4.
Turn on the circuit by inserting the shunt on
jumper JP5 into the ON (upper) position. The output voltage should be regulating to +/-2% of its selected value (see the table below).
No Load
5.
Vary the input voltage from VOUT plus the dropout
voltage (45mV typically at 300mA of output current) to 5.5V and adjust the load current from 0 to
300mA. VOUT should read +/-3% of its selected
value (see the table below).
When finished, turn off the circuit by inserting the
shunt on jumper JP5 into the OFF (lower) position.
Max Load or
Max Load and
Line Variation
Line Variation
2%
2.5%
3%
VOUT = 1.8V
1.764V – 1.836V
1.755V – 1.845V
1.746V – 1.854V
VOUT = 2.5V
2.45V – 2.55V
2.437V – 2.563V
2.425V – 2.575V
VOUT = 3.3V
3.234V – 3.366V
3.217V – 3.383V
3.201V – 3.399V
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 886
300mA VERY LOW DROPOUT LINEAR REGULATOR
Figure 1. Proper Measurement Equipment Setup
Figure 2. Measuring Input or Output Ripple
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 886
300mA VERY LOW DROPOUT LINEAR REGULATOR
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