DC1531A - Demo Manual

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DEMO CIRCUIT 1531
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LT3092EDD
Two-Terminal Current Source
DESCRIPTION
Demonstration circuit 1531A is a two-terminal current source featuring LT®3092. It requires only two
resistors to set an output current between 0.5mA
and 200mA. It is stable without input and output capacitors, offering high DC and AC impedance. It can
be used in many applications such as 2-terminal
floating current source, GND referred current source,
variable current source, in-line limiter and intrinsic
safety circuits.
A key feature of the LT3092 is the capability to supply a wide output current range. By using two external resistors, the output current can be programmed
to any level between 0.5mA and 200mA, while the
input-to-output difference voltage is limited to 40V
and the power dissipation is limited below the thermal limit.
Internal protection circuitry includes reverse-battery
and reverse-current protection, current limiting and
thermal limiting.
LT3092 regulator is offered in the thermally enhanced 8-lead TSOT-23, 3-lead SOT-223 and 8-lead
3mm× 3mm DFN packages.
The LT3092 datasheet gives a complete description
of the part, operation and application information.
The datasheet should be read in conjunction with this
quick start guide for working on or modifying the
demo circuit 1531A.
Design files for this circuit board are available.
Call the LTC factory.
, LTC, LTM, LT and uModule are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
Table 1. Performance Summary ( TA = 25oC )
PARAMETER
CONDITION
VALUE
Minimum Vin-Vout Voltage
IOUT=1mA
1.2V
Maximum Vin-Vout Voltage
Output Current
40V
JP1, IOUT=200mA
200mA ±3%
JP1, IOUT=100mA
100mA ±3%
JP1, IOUT=50mA
50mA ±3%
JP1, IOUT=ADJ
0.5mA~110mA
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DEMO CIRCUIT 1531
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QUICK START PROCEDURE
The DC1531A is easy to set up to evaluate the performance of the LT3092. Refer to Figure 1. for
proper measurement equipment setup and following the procedures below:
1.
Before proceeding to test, use jumper JP1
for the desired output current (200mA,
100mA or 50mA). If the output current is
different from the above values, use the ADJ
option.
2.
Assume 200mA is the desired output. Apply
2V across VIN (to VOUT). The measured IOUT
should be 200mA ± 3% (195mA to 207mA).
3.
Vary Vin-Vout from 2V to 40V. IOUT should
measure 200mA ± 3% (195mA to 207mA).
Note: Minimum Vin-Vout depends on IOUT.
datasheet for dropout curves.
See
Figure 1. Proper Measurement Equipment Setup
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DEMO CIRCUIT 1531
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ADDITIONAL NOTE
Although the LT3092’s design strives to be stable
without any capacitors over a wide variety of operating
conditions, it is not possible to test for all possible
combinations of input and output impedances that the
LT3092 will encounter. These impedances may include
resistive, capacitive and inductive components and
may be complex distributed networks. In addition, the
current source’s value will differ between applications
and its connection may be GND referenced, power
supply referenced or floating in a signal line path. Linear Technology strongly recommends that stability
be tested in circuits for any LT3092 application.
When operating with a capacitor across the SET pin
resistor, external compensation is usually required to
maintain stability and compensate for the introduced
pole. Optional input capacitor, output capacitor or RC
compensation can be installed on the back side of the
DC1531A if necessary. See datasheet for details.
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DEMO CIRCUIT 1531
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