QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1507A
HIGH EFFICIENCY 20MA MONOLITHIC SYNCHRONOUS BUCK REGULATOR
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LTC3632EDD
DESCRIPTION
Demonstration circuit 1507A is a high efficiency step-
down DC/DC converter featuring LTC3632EDD with
internal high side and synchronous power switches
that draws only 12µA quiescent current. It has a wide
4.5V to 50V input range and internal over voltage
monitor capable of protecting the part through 60V
surges. The jumper selectable output is up to 5V.
LTC3632EDD can supply up to 20mA load current
with a programmable peak current limit that provides
a simple method for optimizing efficiency in lower
current applications. With no compensation required,
LTC3632EDD is easily configured with minimal com-
ponents.
Design files for this circuit are available. Call the
LTC Factory
.
LTC is a trademark of Linear Technology Corporation
Table 1. Performance Summary (TA = 25°C)
PARAMETER CONDITION VALUE
Input Voltage Range VIN 4.5V to 50V
Output Voltage VOUT IOUT=1mA to 20mA, VIN=10V VOUT ± 2.7% (LTC3632 Output adjustable version)
Maximum Output Current 20mA
DC Supply Current Active Mode, VIN=10V, IO=0A 125µA
Nominal Switching Frequency Inductance=1000µH, VIN=30V 60kHz
QUICK START PROCEDURE
The DC1507A is easy to set up to evaluate the per-
formance of the LTC3632EDD. For a proper meas-
urement equipment configuration, set up the circuit
according to the diagram in Figure 2.
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 out-
put voltage ripple by touching the probe tip directly
across the VIN or VOUT and GND terminals. See the
Measurement Equipment Set-up diagram in Figure 1
for proper scope probe technique. To reduce the out-
put voltage ripple further additional capacitor of
100µF can be added in parallel.
Please follow the procedure outlined below for proper
operation.
1. Connect the input power supply to the VIN and
GND terminals. Connect the load between the VOUT
and GND terminals. Refer to Figure 2 for the proper
measurement equipment setup.
2. Before proceeding to operation, insert jumper
shunt XJP1 into the OFF position and insert jumper
shunt into JP2 for voltages of 1.8V, 3.3V or 5V re-
spectively. Set the load output current to 20mA.
3. Apply 6V 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 about
5 µA in shutdown. Set the load output current back to
0mA.
4. Turn on VOUT by changing shunt XJP1 from the
OFF position to the ON position. The output voltage
should measure according to the voltage set by the
shunt jumper in JP2.
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1507A
HIGH EFFICIENCY 20MA MONOLITHIC SYNCHRONOUS BUCK REGULATOR
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5. Set the load output current to 1mA. Vary the input
voltage from 6V to 50V and VOUT should be within a
tolerance of ± 2.7%.
6. Set the input voltage to 10V. Vary the VOUT load
current from 1mA to 20mA, and the output voltage
should be within a tolerance of ± 2.7%.
Warning - If the power for the demo board is carried in long leads, the input voltage at the part could “ring”,
which could affect the operation of the circuit or even exceed the maximum voltage rating of the IC. To elimi-
nate the ringing, insert an electrolytic capacitor (for instance, Panasonic part # EEU-FC2A680L, 68µF/100V) on
the pads between the input power and return terminals on the bottom of the demo board. The (greater) ESR of
the electrolytic will dampen the (possible) ringing voltage due to the use of long input leads. On a normal, typi-
cal PCB, with short traces, the capacitor is not needed.
Figure 1. Measuring Input or Output Ripple
Figure 2.
Proper Equipment
Measurement
setup
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1507A
HIGH EFFICIENCY 20MA MONOLITHIC SYNCHRONOUS BUCK REGULATOR
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