Other Parts Discussed in Thread: LM7480-Q1, LM74800-Q1, LM7481-Q1, LM7480, TINA-TI
Tool/software:
I built circuit as in Figure 9-1 of LM74722-Q1 datasheet, but without: D1, D2, Q2, R4, C4. Cload is 22uF.
I noticed that even though DS specifies V(C) (C POR Rising) as 2.8(typ)/2.95(MAX) LM74722 doesn't start boost controller. When V(C) is at 2.8V, gate voltage is even lower (at 2.5V). Only when V(C) rises above 3.05V, gate voltage is equal to V(S) and at 3.1 V(C), it generated ~6V V(G) which is enough to open transistor PMPB07R3ENAX.
Circuit doesn't start if input voltage V(A) is bellow 3.7V. Voltage drop on transistor body diode ~0.55V with no load and increases with load until LM74722 opens the transistor. Load is activated at 3.2V by power good threshold (other TI part).
Is there any work around to lower start up voltage to 3.2V (rising voltage ramp up 0V to 3.2V). Under what conditions 3V operation range (specified in datasheet) was achieved.
Application: power muxing for single cell Li-Ion battery powered device.
