DEMO BOARD QUICK START GUIDE DC398 1.2MHZ SINGLE CELL SYNCHRONOUS BOOST CONVERTER LTC3400 DESCRIPTION Demonstration Circuit DC398 is a micropower boost volts with current guaranteed up to 90mA from a single converter that guarantees to start up at 1V. Once it starts AA cell. When JP1 is closed, the IC is turned off, which up, the chip is powered from the output therefore the draws less than 1A current. input voltage can go lower. DC398 version A uses the On the bench test, an electrolytic capacitor is reco m- LTC3400ES6 version B uses the LTC3400BES6. The mended at the input posts to dump the voltage ove r- TM LTC3400 shifts automatically to low power Burst Mode shoot when first powered up. The spike is caused by the operation at light loads whereas the LTC3400B operates energy stored in the parasitic inductance of the connec- at a fixed frequency for all loads. Both LTC3400 and tion wire. In real applications, since the connection to LTC3400B switch at 1.2MHz to allow up to 95% eff i- the source is short and the battery internal impedance ciency with a tiny PCB footprint, which will fit nicely in also provides damping, the damping capacitor is usually many battery powered applications such as GPS receiv- not needed. The Vin pin is rated for 6V. ers, PDAs, pagers and toys. The converter produces 3.3 QUICK START PROCEDURE Refer to Figure 1 for proper equipment setup and follow 2. Attach a voltmeter or oscilloscope probe between the the procedure below. Vout and GND terminals of the circuit to monitor the output. 1. Apply a voltage source to the input of the circuit be- tween the Vin and GND terminals. The circuit is guar- 3. To start the circuit, open the jumper, JP1. anteed to start up at input voltages higher than 1V. Do 4. Attach a load to the output. The available output not apply more than 5 volts. The boost circuit will power depends on the input voltage. Please refer to only regulate the output voltage when the input volt- the performance summary for maximum current at age is less than the output. different input voltages. Figure 1. Proper Measurement Equipment Setup 1 DEMO BOARD QUICK START GUIDE DC398 1.2MHZ SINGLE CELL SYNCHRONOUS BOOST CONVERTER Table 1. Performance Summary PARAMETER CONDITION VALUE Maximum Load Current, Min V = 3.3V, V = 1.0V 90mA OUT IN Maximum Load Current, Min V = 3.3V, V = 2.0V 250mA OUT IN Switching Frequency, Typ 1.2MHz Efficiency, Typ V = 2.4V, V = 3.3V, I = 100mA 92% IN OUT OUT Output Ripple, Typ V = 1.2V, V = 3.3V, I = 90mA 20mV IN OUT OUT 2