The LT 1308 is a micropower, fixed frequency step-up DC/DC converter that operates from an input voltage as low as 1V. The LT1308 is capable of outputting 5V at a load current of 1A from a single Li-Ion battery, and also features a power-saving burst mode at light loads. High efficiency is maintained over the 1mA to 1A load range. The device contains a low battery detector with a 200 mV reference and shuts down less than 5µA of quiescent current. The no-load quiescent current is 100μa, and the internal NPN type power switch handles the current and voltage drop of 300mv. High frequency 600kHz switching allows the use of small, surface mount components. The current mode architecture of the LT1308 provides fast response to load and line changes. The device is available in an 8-lead SO package. The LT1308 switches current at high speeds, requiring careful attention to layout for proper performance. You won't get advertised performance with careless layout. Figure 2 shows the recommended component locations. Pay close attention to this in your PC layout. Note the direct path of the switch loop. The input capacitor CIN must be close to the IC package (<5mm). As long as there is a 10mm trace of wire or PC from CIN to VIN, it will cause problems such as non-adjustment or oscillation. A 10µf ceramic bypass capacitor is the only input capacitor required to provide a low inductance path from the battery to the circuit. The battery itself provides the volumetric capacitance required for the device to function properly. If the battery is positioned some? The LT1308 is suitable for converting a single Li-Ion battery to 5V to power the GSM RF power stage. Figure 6 details a Li-Ion to 5V converter circuit using frequency compensation optimized for typical GSM pulsed loads. Figure 7 details the transient response of the circuit of Figure 6 under a 100mA to 1A pulsed load. A slower time sweep is used in Figure 8 to show several transmission pulses. At 2.7V, it is recommended to increase the output capacitor to help minimize voltage output drop. Figure 9 shows VOUT with an input voltage of 2.7V. Figure 10 Details of horizontal scan speed expansion to 500µs/sector showing a transmission pulse