Setting the Xpowergood Time | Fujitsu MB3891 guide

MB3891

(8) LDO5

The LDO5 circuits uses the reference voltage supply and generates an output voltage (2.8 V typ.) at the OUT5 terminal (pin 57) when the OUT1 terminal (pin 12,13) is in output state and an “H” level signal is input at the CONT5 terminal (pin 57). Power can be drawn from the OUT5 terminal for external use, up to a maximum load current of 50 mA.

(9) LDO6

The LDO6 circuit uses the reference voltage supply and generates an output voltage (2.1 V typ.) at the V-BACKUP terminal (pin 21). Power can be drawn for external use, from the V-BACKUP terminal, up to a maximum load current of 250 ∝A.

(10) REF-OUT

This circuit uses the reference voltage generated by the reference voltage block (1.225 V typ.) to produce a temperature compensated reference voltage (1.225 V typ.) at the REF-OUT terminal(pin 24) by means of a voltage follower. The reference voltage can also be drawn from the REF-OUT terminal for external use, up to a load current of 50 ∝A.

(11) VSIMOUT Chargepump

The VSIMOUT charge pump uses the voltage from the battery and generates 5.0 V (typ.) voltage at the VSIMOUT terminal (pin 29) when an “H” level signal is input at the SIMPROG terminal (pin 27) , or 3.0 V (typ.) voltage when an “L” level signal input at the SIMPROG terminal. This voltage can also be drawn from the VSIMOUT terminal for external use, up to a load current of 10 mA.

(12) GSM/SIM Logic Translation ∝P Interface

When a signal is input from the microprocessor to the RESET-IN terminal(pin 33) and CLK-IN terminal (pin 34), a level-shifted voltage is output from the RST terminal (pin 36) and CLK terminal (pin 37) to the SIM card. The ∝P-IO terminal (pin 35) and SIM-IO terminal (pin 38) are input/output pins and carry signals between the microprocessor and SIM card.

(13) SIM Interface 5 V (SIMPROG = “H”)

When an “H” level signal is input to the SIMPROG terminal (pin 27), 5.0 V (typ.) voltage is generated from the VSIMOUT terminal (pin 29) as a power supply for the SIM card.

(14) SIM Interface 3 V (SIMPROG = “L”)

When an “L” level signal is input to the SIMPROG terminal (pin 27), 3.0 V (typ.) voltage is generated from the VSIMOUT terminal (pin 29) as a power supply for the SIM card.

■SETTING THE XPOWERGOOD TIME

When the OUT1 terminal (pin 12,13) voltage exceeds 2.0 V (typ.), the capacitor (CDELAYCAP) connected to the DELAYCAP terminal (pin 18) starts charging, the XPOWERGOOD terminal (pin 17) voltage rises. The XPOW- ERGOOD terminal voltage rising time (XPOWERGOOD time) can be set by a capacitor connected to the DELAYCAP terminal.

XPOWERGOOD time : TXPG (s) =: 0.8 ⋅ CDELAYCAP (∝F)