AS1346-49 Dual Step-Down Converter with Battery Monitoring 1 General Description 2 Key Features High Efficiency: Up to 95% The AS1346, AS1347, AS1348, AS1349 family is a high-efficiency, constant-frequency dual buck converter available with fixed voltage Output Current: see Table 1 versions. The device provides two independent DC/DC Converters with output currents between 0.5A and 1.2A. The wide input voltage Input Voltage Range: 2.7V to 5.5V range (2.7V to 5.5V), automatic powersave mode and minimal Output Voltage Range: 1.2V to 3.6V (available in 100mV steps) external component requirements make the AS134x family perfect for SSD and many other battery-powered applications. Constant Frequency Operation: 2.0MHz In shutdown mode the typical supply current decreases to 1 A. 180 Out of Phase Operation The highly efficient duty cycle (100%) provides low dropout Low Battery Detection operation, prolonging battery life in portable systems. An internal synchronous switching scheme increases efficiency and Low Dropout Operation: 100% Duty Cycle eliminates the need for an external Schottky diode. The fixed Shutdown Mode Supply Current: 1 A switching frequency (2.0MHz) allows the use of small surface mount inductors. No Schottky Diode Required The integrated monitoring function can be configured that either the Output Disconnect in Shutdown output voltage (Power Okay function ) or the input voltage (Battery Monitoring Function) can be supervised. Non standard variants available within two weeks Table 1. Available Products 12-Pin TDFN 3x3mm Package Devices IOUT1 IOUT2 AS1346 1.2A 0.5A 3 Applications AS1347 0.5A 0.5A The device is ideal for SSD applications, mobile communication AS1348 0.5A 0.95A devices, laptops and PDAs, ultra-low-power systems, threshold detectors/discriminators, telemetry and remote systems, medical AS1349 1.2A 1.2A instruments, or any other space-limited application with low power- consumption requirements. The AS1346-49 is available in a 12-Pin TDFN 3x3mm package. Figure 1. AS1346 - Typical Application Diagram with POK Function L1 = 3.3 H VIN VOUT1 2.7V to 5.5V 3.3V 1200mA PVIN SW1 CIN COUT1 PVIN FB1 AS1346 L2 = 3.3 H VOUT2 1.8V 500mA VDD SW2 COUT2 EN1 FB2 POK Function EN2 LBO LBI AGND PGND www.ams.com/DC-DC Step-Down Revision 1.10 1 - 16AS1346-49 Datasheet - Pin Assignments 4 Pin Assignments Figure 2. Pin Assignments (Top View) SW1 1 12 SW2 PVIN PVIN 2 11 EN1 3 10 VDD AS1346 FB1 4 9 FB2 AGND EN2 5 8 LBO 6 7 LBI 13 4.1 Pin Descriptions Table 2. Pin Descriptions Pin Number Pin Name Description Switch Node1 Connection to Inductor. This pin connects to the drains of the internal main and 1 SW1 synchronous power MOSFET switches. Power Supply Connector. This pin must be closely decoupled to PGND with a 4.7F ceramic 2, 11 PVIN capacitor. Enable1 Input. Driving this pin above 1.2V enables VOUT1. Driving this pin below 0.5V puts the device in shutdown mode. In shutdown mode all functions are disabled, drawing 1 A supply current. 3 EN1 This pin should not be left floating. Feedback Pin 1. Feedback input to the error amplifier, connect this pin to VOUT1. The output can be 4 FB1 factory set from 1.2V to 3.6V. For further information see Ordering Information on page 15. Enable2 Input. Driving this pin above 1.2V enables VOUT2. Driving this pin below 0.5V puts the device in shutdown mode. In shutdown mode all functions are disabled, drawing 1 A supply current. 5 EN2 This pin should not be left floating. Low Battery Comperator Output. This open-drain output is low when: 6 - the voltage on LBI is higher than 1.2V or LBO - LBI is connected to GND and VOUT1 is below 92.5% of its nominal value. Low Battery Comperator Input. 1.2V Threshold. May not be left floating. If connected to GND, LBO is 7 LBI working as Output Power Okay for VOUT1. 8 AGND Analog Ground. Feedback 2 Pin. Feedback input to the error amplifier, connect this pin to VOUT2. The output can be 9 FB2 factory set from 1.2V to 3.6V. For further information see Ordering Information on page 15. Supply Connector. Connect this pin to PVIN 10 VDD Switch Node2 Connection to Inductor. This pin connects to the drains of the internal main and 12 SW2 synchronous power MOSFET switches. Exposed Pad. The exposed pad must be connected to AGND. Ensure a good electrical connection to the 13 PGND PCB to achieve optimal thermal performance. www.ams.com/DC-DC Step-Down Revision 1.10 2 - 16