Datasheet

71M6521DE/DH/FE Data Sheet
Rev 3 Page: 51 of 107
Circuit Function
System Power
Battery Power (Non-volatile Supply)
1B
MISSION
BROWNOUT LCD SLEEP
CE
Yes
--
--
--
CE Data RAM
Yes
Yes
--
--
FIR
Yes
--
--
--
Analog circuits:
PLL, ADC, VREF, BME etc
Yes -- -- --
MPU clock rate
4.92MHz
(from PLL)
28.672kHz
(7/8 of 32768Hz)
-- --
MPU_DIV
Yes
--
--
--
ICE
Yes
Yes
--
--
DIO Pins
Yes
Yes
--
--
Watchdog Timer
Yes
Yes
--
--
LCD
Yes
Yes
Yes
--
EEPROM Interface (2-wire)
Yes
Yes (8kb/s)
--
--
EEPROM Interface (3-wire)
Yes
Yes (16kb/s)
--
--
UART
Yes
Yes
--
--
Optical TX modulation
Yes
--
--
--
Flash Read
Yes
Yes
--
--
Flash Page Erase
Yes
Yes
--
--
Flash Write
Yes
--
--
--
RAM Read and Write
Yes
Yes
--
--
Wakeup Timer
Yes
Yes
Yes
Yes
Oscillator and RTC
Yes
Yes
Yes
Yes
DRAM data preservation
Yes
Yes
--
--
V3P3D voltage output pin
Yes
Yes
--
--
Table 60: Available Circuit Functions (“—means “not active”)
BROWNOUT Mode
In BROWNOUT mode, most non-metering digital functions, as shown in Table 60, are active, including ICE, UART,
EEPROM, LCD, and RTC. In BROWNOUT mode, a low bias current regulator will provide 2.5 Volts to V2P5 and
V2P5NV. The regulator has an output called BAT_OK to indicate that it has sufficient overhead. When BAT_OK = 0,
the part will enter SLEEP mode. From BROWNOUT mode, the MPU can voluntarily enter LCD or SLEEP modes.
When system power is restored, the part will automatically transition from any of the battery modes to mission mode,
once the PLL has settled.
The MPU will run at crystal clock rate in BROWNOUT. The value of MPU_DIV will be remembered (not changed) as
the part enters and exits BROWNOUT. MPU_DIV will be ignored during BROWNOUT.
While PLL_OK = 0, the I/O RAM bits ADC_E and CE_E are held in zero state disabling both ADC and CE. When
PLL_OK falls, the CE program counter is cleared immediately and all FIR processing halts. Figure 19 shows the
functional blocks active in BROWNOUT mode.