DEMO MANUAL DC2160A LTC4419 18V Dual Input Micropower PowerPath Prioritizer DESCRIPTION Demonstration circuit 2160A uses the LTC 4419 to The second auxiliary comparator CMP2 divider (R8-R7) is provide backup switchover, keeping the output load adjusted to trigger the comparator when VCMP2 TOPs powered during brown out or power loss conditions. voltage is in the 3.26V to 3.53V range. Overcurrent (0.5A Priority is assigned by supply connection to the V1 and to 1.6A) and thermal protection inherent to the LTC4419 V2 inputs. The power source connected to V1 has a higher allows safe prioritization. Overtemperature protection is priority and is monitored by undervoltage switchover activated when the junction temperature exceeds 125C. threshold comparator CADJ (pin ADJ). If V1 exceeds Another inherent feature reverse supply protection 1.55V and ADJ is above 1.097V for 64ms, V1 is considered protects the prioritizer and load when a negative voltage valid, and the LTC4419 connects V1 to the load. If V1 (up to 15V) is applied to any input V1 or V2. drops below 1.52V, or ADJ drops below 1.047V, V1 is The LTC4419s break-before-make switching method considered invalid, and the LTC4419 powers the load prevents cross conduction between input channels. The from V2. The DC2160A is populated to provide switchover LTC4419 does not connect any input source to the load when V1 drops below 10.19V 0.33V. The upper limit for until the input voltage exceeds the output by 50mV. This V1 is the maximum operating voltage, 18V however, the eliminates reverse current from the output into the selected recommended V1 voltage is 12V. The resistive divider (R1- input supply. R2) of the first auxiliary comparator CMP1 is adjusted to trigger the comparator when VCMP1 TOPs voltage is in Design files for this circuit board are available at the 9.92V to 10.74V range. Practically, any voltage from DEMO MANUAL DC2160A OVERVIEW and measuring instrument. Auxiliary componentsLDO The DC2160A includes the LTC4419 2-input pri- and logicare placed on the bottom side of board. oritizer(U1), LDO regulator with 2.5V output voltage (U2-LT1763) for powering LEDs and logic, four LEDs The DC2160A design permits operation of each channel (D4-D7) for visual information, two jumpers (JP1, JP2) over its full operating voltage range. for selecting the power source for the LDO, push but- Provision is made for increasing the hysteresis of auxil- ton(SW1) for engaging freshness seal mode, and a few iary comparator 1 and auxiliary comparator 2 by placing turrets for connecting the board to power sources, load optional resistors R17/R19. TURRETS V1 (E1): 12V supply input should not exceed +18V, and CMP1 (E4): First auxiliary comparator CMP1 non-inverting should be larger than 15V. input. V2 (E8): 5V supply input should not exceed +18V, and CMP2 (E6): Second auxiliary comparator CMP2 non- should be larger than 15V. inverting input. ADJ (E3): Adjustable comparator non-inverting input for GND (E5, E11, and E12): Common ground terminal. setting switchover threshold level. OUT (E9): Output for up to 2A load. VCMP1 TOP (E2): Input for voltage monitored by first LDO EXT (E13): Positive terminal for external auxiliary auxiliary comparator CMP1. 3.5V to 20V power supply. VCMP2 TOP (E7): Input for voltage monitored by second V2P5V (E10): LDO output voltage terminal (2.5V). auxiliary comparator CMP2. JUMPERS JP1, LDO: ON/OFF switch for LDO. JP2, LDO POWER: Power supply selection for LDO. LEDS D4: Indicates LDO output voltage. D6: Indicates second auxiliary comparator output stage (CMPOUT2 pin). D5: Indicates first auxiliary comparator output stage (CMPOUT1 pin). D7: Indicates powering load from V2 source. dc2160af 2