DC801A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 801
INVERTING DC/DC CONVERTER
LT3483ES6
DESCRIPTION
Demonstration circuit 801 is a general purpose positive to negative converter featuring the LT®3483ES6.
The demo board demonstrates two separate DC/DC
converters. One converter generates a -8V at 20mA to
30mA from a 2.7V-4.2V input using a step up inverting charge pump topology. The other uses a dual
coupled inductor in an inverting flyback topology to
generate a -15V at 8mA to 40mA from a 2.7-12V input. This topology is useful to generate output voltages of lower, equal or higher magnitude than the
input. For example, for a -12V supply just change the
value of R2 to 1.21M and for a -5V, change R2 to
511K. Both circuits demonstrate low component
count and are intended for space-conscious applications such as LCD bias, Handheld Computers, Battery
Backup, Digital Cameras and OLED Bias.
Design files for this circuit board are available. Call
the LTC factory.
LTC is a registered trademark of Linear Technology Corporation
Table 1. Performance Summary (TA = 25°C)
PARAMETERS FOR -8V INVERTER
CONDITION
VALUE
Minimum Input Voltage
2.7V
Maximum Input Voltage
4.2V
Output Voltage VOUT
Vin = 2.5V to 4.2V, Iout = 20mA to 30mA
-8V ±3%
Typical efficiency
VIN =3.3V, Iout =25mA
67%
Typical Output Ripple
VIN = 3.3V, IOUT = 25mA
60mVP–P
PARAMETERS FOR -15V INVERTER
VALUE
Minimum Input Voltage
2.7V
Maximum Input Voltage
12V
Output Voltage VOUT
VIN = 2.7V to 12V, IOUT = 8mA to 40mA
-15V ±3%
Typical efficiency
VIN = 6V, IOUT = 20mA
75%
Typical Output Ripple VOUT
VIN = 6V, IOUT = 20mA
80mVP–P
QUICK START PROCEDURE
Demonstration circuit 801 is easy to set up to evaluate the performance of the LT3483ES6. Refer to Figure 1 for proper measurement equipment setup and
follow the procedure below:
on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly
across the Vin or Vout and GND terminals. See Figure
2 for proper scope probe technique.
NOTE: When
1.
measuring the input or output voltage
ripple, care must be taken to avoid a long ground lead
Place jumper in the following positions for testing
of -15V inverter:
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 801
INVERTING DC/DC CONVERTER
JP1 On
2.
With power off, connect the input power supply to
Vin and GND.
3.
Turn on the power at the input.
4.
Check for the proper output voltages.
5.
Once the proper output voltages are established,
adjust the loads within the operating range and observe the output voltage regulation, ripple voltage,
efficiency and other parameters.
6.
For testing of -8V Inverter repeat steps 1-5 placing
JP2 in the ON position.
NOTE: If
there is no output, temporarily disconnect
the load to make sure that the load is not set too
high.
Figure 1. Proper Measurement Equipment Setup
2
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 801
INVERTING DC/DC CONVERTER
Figure 2. Measuring Input or Output Ripple
3
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 801
INVERTING DC/DC CONVERTER
4
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