Demo Board DC409 Quick Start Guide
The LTC3402 is a high efficiency, step-up DC/DC converter that starts up from an input
voltage as low as 1V. Once it starts up, the LTC3402 is supplied from the output voltage
and the input voltage can go well below 1V. The device includes a 0.16Ω N-channel
MOSFET and a 0.18Ω P-channel synchronous rectifier, which give higher than 90%
efficiency in many applications. Switching frequencies are programmed with an external
resistor and can also be synchronized to an external clock.
Demonstration Circuit DC409 demonstrates a 600kHz converter that achieves a useful
balance of efficiency and size. The output voltage of this circuit is jumper selectable
between 3.3V and 5V. (This demo board ships with the output set to 5V. To change the
output to 3.3V, remove jumper JP2.)
Performance Summary
Available power for this circuit depends on input and output voltages. The following
table shows Maximum load current for several input-output conditions.
Parameter Condition Value
Maximum Load Current V
OUT
= 3.3V, V
IN
= 2.0V
V
OUT
= 5.0V, V
IN
= 2.0V
V
OUT
= 5.0V, V
IN
= 2.7V
850mA
550mA
800mA
Quick start guide
Refer to Figure 1 for proper measurement equipment setup and Figure 2 for the proper
ripple measurement technique. Then, follow this procedure:
1.
Apply a voltage source to the input of the circuit between the V
IN
and GND terminals.
The circuit will start up with an input voltage higher than 1V. Do not apply more than
5V to the input. Note that the boost circuit will regulate the output only when the
input voltage is less than the desired output voltage.
2.
Attach a voltmeter or oscilloscope probe between the V
OUT
and GND terminals of the
circuit to monitor the output.
3.
Attach a load to the output.
The available output power depends on the input and output voltages. Please refer to
the performance summary above for maximum current at different inputs and outputs.
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