QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 534
LOW VOLTAGE LDO LINEAR REGULATOR
1
LT3150
DESCRIPTION
Demonstration circuit 534 is a fast transient response,
very low dropout linear regulator featuring the LT3150
linear regulator. The DC534 generates fixed output volt-
ages of 1.2V, 1.5V, and 1.8V, and is capable of delivering
4A (max.) of output current. With the LT3150 driving
external N-channel MOSFETs as source followers, the
DC534 can produce very fast transient response. The
proper selection of the Rds(on) of the MOSFETs allows
dropout voltages below 300 mV. These capabilities, plus
its ability of maintaining stable operation with ceramic
output capacitors, make the DC534 voltage regulator
ideally suited for low Vin to Vout applications, such as
microprocessor power supplies.
Design files for this circuit board are available. Call
the LTC factory.
Table 1. Performance Summary
PARAMETER CONDITION VALUE
Minimum Input Voltage 1.1V
Maximum Input Voltage 10V
V
OUT1
V
IN
= 1.5V, I
OUT1
= 0A to 4A 1.2V ±2%
V
OUT2
V
IN
= 1.8V, I
OUT2
= 0A to 4A 1.5V ±2%
V
OUT3
V
IN
= 2.5V, I
OUT3
= 0A to 1.7A 1.8V ±2%
Typical Output Ripple I
OUT(MAX)
10mV
P–P
QUICK START PROCEDURE
Demonstration circuit 534 is easy to set up to evaluate
the performance of the LT3150. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
NOTE:
When measuring the input or output voltage rip-
ple, 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 VIN1 or VOUT and GND terminals. See Figure 2 for
proper scope probe technique.
1.
Connect the input power supply and voltmeter to the
VIN1 and GND terminals on the right side of the
board.
2.
Connect the load and voltmeter between the VOUT
and GND terminals on the right side of the board.
3.
For oscilloscope observations, connect a BNC cable
from the oscilloscope to connector J1, located on the
right side of the board.
4.
Before proceeding to test, set the output voltage to
1.2V, using the Output Voltage Table on the sche-
matic.
5.
Apply 1.5V across VIN (to GND) with 100mA of load
current. Measure V
OUT
; it should be 1.23V ±1%
(1.218V to –1.242V).
6.
Increase the load current to 4A. Measure V
OUT
again;
it should be 1.22V ±2% (1.205V to 1.255V). When
finished, return I
OUT
to 100mA.
7.
Increase the input voltage to 1.8V. Change the jump-
ers for an output voltage of 1.5V (again see the Out-
put Voltage Table below). Measure V
OUT
; it should be
1.5 ±1% (1.485V to 1.515V).
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 534
LOW VOLTAGE LDO LINEAR REGULATOR
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8.
Increase the load current to 4A. Measure V
OUT
again;
it should be 1.5V ±2% (1.470V to 1.530V). When fin-
ished, return I
OUT
to 100mA.
9.
Increase the input voltage to 2.5V. Change the jump-
ers for an output voltage of 1.8V (again see the Out-
put Voltage Table below). Measure V
OUT
; it should be
1.8 ±1% (1.782V to 1.818V).
10.
Increase the load current to 1.7A. Measure V
OUT
again; it should be 1.8V ±2% (1.764V to 1.836V).
When finished, return I
OUT
to 100mA.
Figure 1. Proper Measurement Equipment Setup
VIN
GND
Figure 2. Measuring Input or Output Ripple
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 534
LOW VOLTAGE LDO LINEAR REGULATOR
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