Datasheet LTC4417 (Linear Technology) - 19

LTC4417 priority back up input supplies. An internal diode-OR est input voltage input supply as the source. See Typical structure selects the highest voltage input supply as the Performance Characteristics for more detail. source for VBLDO. If two supplies are similar in voltage and higher than the remaining input supply, the current will be
DUAL SUPPLY OPERATION
equally divided between the similar voltage supplies. If all input supplies are equal in voltage, the current is divided For instances where only two supplies are prioritized and evenly between them. no features of the third channel are used, ground the V3, OV3, UV3, VS3 and G3 pins of the unused channel. To limit current consumption from lower priority backup Alternatively, the lowest priority OV and UV comparators supplies, the LTC4417 prioritizes the internal VLDO’s source can be utilized for voltage monitoring when V3 and VS3 supply. The highest priority source is VOUT, which powers are connected to the output and G3 is left open. Figure 11 the VLDO when VOUT is above 2.4V. If VOUT is lower than shows an example of the spare OV and UV comparators 2.4V, VLDO switches to the highest valid priority input used to monitor the 5V output of the LTC3060. VALID3 supply, V1, V2 and V3. If no input supply is valid, VLDO acts as an open drain OV/UV window comparator output. is connected to VBLDO, where the diode-OR selects high- 12V WALL IRF7324 ADAPTER M1 M2 + VOUT + CIN CL 2200µF 100µF 14.4V NiCd IRF7324 BATTERY M3 M4 + CS 6.8nF LTC3060 LINEAR CVS1 CVS2 REGULATOR 0.1µF 1µF DS RS BAT54 2.21k 5V OUTPUT CV3 CV2 CV1 VS1 G1 VS2 G2 VS3 G3 R10 R11 R12 0.1µF 0.1µF 0.1µF V1 VOUT 1M 1M 1M R3 806k UV1 V1 INVALID R2 VALID1 39.2k V2 INVALID VALID2 OV1 R1 5V OUTPUT INVALID VALID3 60.4k V2 R6 845k LTC4417 UV2 R5 26.1k OV2 R4 51.1k V3 EN R9 SHDN 340k HYS UV3 R8 CAS 21.5k OV3 GND R7 4417 F11 78.7k
Figure 11. Dual Channel with Output Voltage Monitoring
4417f 19 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Timing Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts