DC878A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 878
1MHZ SYNCHRONOUS STEP-UP DC/DC CONVERTER
LTC3458LEDE
DESCRIPTION
Demonstration circuit 878 is a 1MHZ Synchronous
Step-Up
DC/DC
Converter
featuring
the
LTC®3458LEDE. The demo board demonstrates a
DC/DC boost converter, with a 1.7A switch, providing
5V at 300mA to 900mA depending on input voltage.
The circuit demonstrates the advantages of output
disconnect and inrush current limiting. Small circuit
size and low component count make the LTC3458L
suitable for use in many space-conscious applications such as handheld instruments, point-of-load
converters, USB VBUS Power and OLED displays.
Other integrated features include externally programmable burst mode threshold, peak current limit,
soft-start, antiringing control and thermal shutdown.
Design files for this circuit board are available. Call
the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Table 1. Performance Summary (TA = 25°C)
PARAMETERS
CONDITION
VALUE
Minimum Input Voltage
2.0V
Maximum Input Voltage
5V
Output Voltage VOUT
VIN = 2V, IOUT =300mA
5V ±3%
Output Voltage VOUT
VIN = 2.7V, IOUT =450mA
5V ±3%
Output Voltage VOUT
VIN = 3.3V, IOUT =650mA
5V ±3%
Output Voltage VOUT
VIN = 4.2V, IOUT =900mA
5V ±3%
Typical Output Ripple VOUT
VIN = 3.3V, IOUT = 650mA
30mVP–P
Typical efficiency
VIN =4.2V , IOUT = 900mA
86%
C9 used only when operating supply with long inductive input leads.
QUICK START PROCEDURE
Demonstration circuit 878 is easy to set up to evaluate the performance of the LTC3458LEDE. Refer to
Figure 1 for proper measurement equipment setup
and follow the procedure below:
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 Vin or Vout and GND terminals. See
Figure 2 for proper scope probe technique.
1.
Place jumpers in the following positions:
JP1 Run, JP2 Auto on.
2.
With power off, connect the input power supply to
Vin and GND.
3.
Turn on the power at the input.
NOTE: Make
sure that the input voltage does not ex-
ceed 6V.
4.
Check for the proper output voltages.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 878
1MHZ SYNCHRONOUS STEP-UP DC/DC CONVERTER
NOTE: If there is no output, temporarily disconnect
the load to make sure that the load is not set too
high.
and observe the output voltage regulation, ripple
voltage, efficiency and other parameters.
NOTE: Once
the proper output voltages are established, adjust the loads within the operating range
Figure 1. Proper Measurement Equipment Setup
Figure 2. Measuring Input or Output Ripple
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 878
1MHZ SYNCHRONOUS STEP-UP DC/DC CONVERTER
3
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