AS1340 50V, Micropower, DC-DC Boost Converter 1 General Description 2 Key Features 2.7V to 50V Adjustable Output Voltage The AS1340 boost converter contains a 1.4A internal switch in a tiny TDFN-8 3x3mm package. The device operates from a 2.7 to 5.5V 2.7V to 50V Input Voltage Range supply, and can boost voltages up to 50V output. 2.7V to 5.5V Supply Voltage Range The output voltage can easily be adjusted by an external resistor divider. High Output Currents: The AS1340 uses a unique control scheme providing the highest - 100mA 12V from 3.3V VIN efficiency over a wide range of load conditions. An internal 1.4A - 50mA 24V from 3.3V VIN MOSFET reduces external component count, and a fixed high - 30mA 36V from 3.3V VIN switching frequency (1MHz) allows for tiny surface-mount components. Efficiency: Up to 93% The AS1340 also features power-OK circuitry which monitors the Switching Frequency: 1MHz output voltage. Output Disconnect Additionally the AS1340 features a low quiescent supply current and a shutdown mode to save power. During shutdown an output Power-OK Output disconnect switch separates the input from the output. Operating Supply Current: 30A The AS1340 is ideal for LCD or OLED panels with low current requirements and can also be used in a wide range of other Shutdown Current: 0.1A applications. TDFN-8 3x3mm Package The device is available in a low-profile TDFN-8 3x3mm package. 3 Applications The device is ideal for OLED display power supply, LED power supply, LCD bias generators, mobile/cordless phones, palmtop computers, PDAs and organizers, handy terminals or any other portable, battery-powered device. Figure 1. AS1340 - Typical Application Diagram L1 L1 4.7H 3 6 VIN = 2.7V to VOUT 3 6 5.5V SWVIN SWOUT VCC LX VIN = 2.7V VOUT = > VIN to 50V to 5.5V 5 2 LX VCC CIN COUT R1 VIN = 2.7V to L1 AS1340 4 8 ~VOUT POK FB 3 6 R2 VIN = 2.7V to VOUT 5.5V 7, 9 1 On VCC LX Off GND EN If not needed the output disconnect switch can be left unconnected which will also increase the efficiency. Additionally the supply of the chip can be split to allow higher supply voltages for the coil. In this case the output disconnect switch must not be used. www.ams.com/DC-DC Step-Up/AS1340 Revision 1.20 1 - 17AS1340 Datasheet - Pin Assignments 4 Pin Assignments Figure 2. Pin Assignments (Top View) EN 1 8 FB VCC 2 7GND AS1340 SWVIN 3 6SWOUT GND 9 POK 4 5 LX 4.1 Pin Descriptions Table 1. Pin Descriptions Pin Number Pin Name Description Active-High Enable Input. A logic low on this pin shuts down the device and reduces the supply current to 0.1A. 1EN Note: Connect to VCC for normal operation. +2.7V to +5.5V Supply Voltage. Bypass this pin to GND with a 1F capacitor. 2VCC Shutdown Disconnect Switch In 3SWVIN Power-OK. 4POK 0 = VOUT < 90% of VOUTNOM. 1 = VOUT > 90% of VOUTNOM. Inductor. The drain of the internal N-channel MOSFET. 5LX Note: This pin is high impedance in shutdown. Shutdown Disconnect Switch Out. Disconnects the input from the output during shutdown. 6SWOUT Ground. This pin and pin 9 must be connected to GND to ensure normal operation. 7GND Feedback Pin. Feedback input to the gm error amplifier. Connect a resistor divider tap to this pin. The 8FB output voltage can be adjusted from VIN to 50V by: VOUT = 1.25V 1 + (R1/R2) Ground. This pin and pin 7 must be connected to GND to ensure normal operation. 9GND www.ams.com/DC-DC Step-Up/AS1340 Revision 1.20 2 - 17