LTC4420 18V Dual Input Micropower PowerPath Prioritizer with Backup Supply Monitoring FEATURES DESCRIPTION n Selects Highest Priority Valid Supply from Two The LTC 4420 is a dual input monolithic PowerPath prioritizer, with low operating current, that provides Inputs n backup switchover for keeping critical circuitry alive dur- Wide 1.8V to 18V Operating Range n ing brownout and power loss conditions. Unlike diode-OR Internal Dual 2, 0.5A Switches n products, little current is drawn from the inactive supply Low 3.6A Operating Current n even if its voltage is greater than the active supply. Low 320nA V2 Current When V1 Connected to OUT n Blocks Reverse and Cross Conduction Currents Internal 2, current limited PMOS switches provide n Reverse Supply Protection to 15V power path selection from a primary input (V1) or a backup n Built-In V2 Test with Optional V2 Disconnect input (V2) to the output. Two adjustable voltage monitors n V2 Freshness Seal/Ship Mode set via external resistive dividers provide flexibility in set- n 1.5% Accurate Adjustable Switchover Threshold ting V1 to V2 switchover and V2 undervoltage thresholds. n 2.3% Accurate V2 Monitor and Comparator V1 is monitored continuously while V2 supply monitoring n Overcurrent and Thermal Protection includes controllable low duty cycle UV monitoring. When n Thermally Enhanced 12-Pin 3mm 3mm primary input V1 drops, the ADJ monitor causes OUT to DFN and 12-Lead Exposed Pad MSOP Packages be switched to V2. When V2 drops, it is disconnected from OUT if V2DIS is low. Fast non-overlap switchover circuitry prevents reverse and cross conduction while minimizing APPLICATIONS output droop. n Low Power Battery Backup Auxiliary voltage monitor CMP1 provides flexible voltage n Portable Equipment monitoring and output V2OK provides V2 undervoltage n Point-of-Sale (POS) Equipment status. Freshness seal mode prevents V2 battery discharge during storage or shipment. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and PowerPath and ThinSOT are trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners. TYPICAL APPLICATION Typical Switchover Waveforms 5V WALL V1 OUT OUT ADAPTER 1M 1M 1M V2 MONITORING ADJ V1UV 10F CMPOUT1 INTERVAL 237k V2 2V/DIV CMP1 V2OK V2OK SWITCHOVER 121k V1 THRESHOLD LTC4420 2V/DIV V2 UNDERVOLTAGE AND DISCONNECT V2 V2DIS + 7.4V 4.02M Li-Ion V2UV V2TEST OUT C = 10F OUT 280k I = 100mA TYPICAL VALUES: LOAD GNDSW SWITCHOVER THRESHOLD: V1 < 4V (V1 FALLING) 4420 TA01b 20ms/DIV V1UV THRESHOLD: V1 < 4.4V (V1 FALLING) GND 4420 TA01a V2OK THRESHOLD: V2 < 6V (V2 FALLING) 4420fa 1 For more information www.linear.com/LTC4420LTC4420 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) Terminal Voltages Pin Currents (Note 2) V1, V2 ......................................................15V to 24V ADJ, CMP1, V2UV, CMPOUT1, GNDSW .............1mA OUT ....................................................... 0.3V to 24V V2TEST, V2DIS, V2OK ......................................1mA OUT V2 .................................................24V to 39V Operating Ambient Temperature Range OUT V1 .................................................24V to 39V LTC4420C ................................................ 0C to 70C Input Voltages LTC4420I .............................................40C to 85C ADJ, CMP1, V2UV, V2TEST, V2DIS Junction Temperature (Notes 4, 5) ........................ 125C (Note 3) ................................................ 0.3V to 24V Storage Temperature Range .................. 65C to 150C Output Voltages Lead Temperature (Soldering, 10 sec) CMPOUT1, GNDSW, V2OK (Note 3) ...... 0.3V to 24V MSOP Package .................................................300C PIN CONFIGURATION TOP VIEW TOP VIEW 1 V2 V1 12 1 V1 12 V2 V2DIS V2TEST 2 11 V2TEST 2 11 V2DIS 3 CMP1 10 V2UV CMP1 3 13 10 V2UV 13 GND GND ADJ 4 9 OUT ADJ 4 9 OUT GND 5 8 V2OK GND 5 8 V2OK CMPOUT1 6 7 GNDSW CMPOUT1 6 7 GNDSW MSE PACKAGE DD PACKAGE 12-LEAD PLASTIC MSOP 12-LEAD (3mm 3mm) PLASTIC DFN T = 125C, = 40C/W JMAX JA T = 125C, = 43C/W JMAX JA EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB