DC932A - Demo Manual

1A, Low Voltage, Very Low Dropout
Linear Regulator
Demonstration circuit 932A is an adjustable 1A linear
regulator featuring LT3022. The LT3022 is a very low
dropout voltage (VLDOTM) linear regulator that operates
from input supplies down to 0.9V. The device supplies
1A output current with 145mV typical dropout voltage.
The LT3022 is ideal for low input voltage to low output
voltage applications, providing comparable electrical efficiency to a switching regulator. The regulator optimizes
stability and transient response with low ESR ceramic
output capacitors as small as 10μF. Other LT3022 features include 0.05% typical line regulation and 0.05%
typical load regulation. In shutdown, the quiescent current typically drops to 7.5μA. Internal protection circuitry
includes reverse-battery protection, current limiting,
thermal limiting with hysteresis and reverse-current protection.
Minimum input voltage is the voltage required by the
LT3022 to regulate the output voltage and supply the
rated 1A output current. This specification is tested at
VOUT = 0.2V. For higher output voltages, the minimum
input voltage required for regulation equals the regulated
output voltage VOUT plus the dropout voltage or 1.1V,
whichever is greater.
The LT3022 is available as an adjustable device with an
output voltage range down to the 200mV reference. The
LT3022 regulator is available in the thermally enhanced
low profile (0.75mm) 16-lead (5mm × 3mm) DFN and
MSOP packages.
The LT3022 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 demo circuit 932A.
Design files for this circuit board are available. Call
the LTC factory.
L, LTC and LT are registered trademarks of Linear Technology Corporation. VLDO is a trade
mark of Linear Technology Corporation. Other product names may be trademarks of the
companies that manufacture the products.
Performance Summary ( TA = 25oC )
Minimum Input Voltage
Maximum Input Voltage
Output Voltage VOUT
VOUT = 1.2V, IOUT = 1A
Shunt at 1, 2 for JP2
Shunt at 3, 4 for JP2
Shunt at 5, 6 for JP2
Shunt at 7, 8 for JP2
Shunt at 9, 10 for JP2
Shunt at 11, 12 for JP2
0.9V ± 3%
1.0V ± 3%
1.2V ± 3%
1.5V ± 3%
1.8V ± 3%
User Select
Demonstration circuit 932A is easy to set up to evaluate
the performance of the LT3022. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
4. Turn on the power at the input.
NOTE. Make sure that the input voltage does not exceed 10V.
5. Check for the proper output voltages.
NOTE. If there is no output, temporarily disconnect the load to make
sure that the load is not set too high or is shorted.
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
terminals of the input or output capacitors. See Figure 2 for proper scope
probe technique.
6. Once the proper output voltage is established, adjust
the loads within the operating range and observe the
output voltage regulation, efficiency and other parameters.
1. Place JP1 on the ON position.
2. Use JP2 to set the desired output voltage.
3. With power off, connect the input power supply to
VIN and GND.
NOTE. Make sure that the power dissipation is limited below the
thermal limit.
Figure 1. Measurement Equipment Setup
Figure 2. Measuring Input or Output Ripple