71M6533 Datasheet, PDF (56/124 Pages) Teridian Semiconductor Corporation – Energy Meter IC

71M6533/71M6534 Data Sheet
FDS_6533_6534_004
2.3.1 BROWNOUT Mode
In BROWNOUT mode, most non-metering digital functions are active (as shown in Table 45) 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 suffi-
cient overhead. When BAT_OK = 0, the part will enter SLEEP mode. From BROWNOUT mode, the pro-
cessor can voluntarily enter LCD or SLEEP modes. When system power is restored, the part will auto-
matically transition from any of the battery modes to MISSION mode, once the PLL has settled.
Table 45: Available Circuit Functions
Circuit Function
CE
CE/MPU Data RAM
FIR
Analog circuits:
MPU clock rate
MPU_DIV
ICE
DIO Pins
Watchdog Timer
LCD
EEPROM Interface (2-wire)
EEPROM Interface (3-wire)
UART
Optical TX modulation
Flash Read
Flash Page Erase
Flash Write
XRAM Read and Write
Wakeup Timer
Oscillator and RTC
XRAM data preservation
V3P3D voltage output pin
GPO – GP7 registers
– indicates not active
System Power
MISSION
Yes
Yes
Yes
Yes
From PLL, as de-
fined by MPU_DIV
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Battery Power (Nonvolatile Supply)
BROWNOUT
LCD
SLEEP
–
–
–
Yes
–
–
–
–
–
–
–
–
28.672 kHz
–
–
(7/8 of 32768 Hz)
–
–
–
Yes
–
–
Yes
–
–
Yes
–
–
Yes
Yes
–
Yes (8 kb/s)
–
–
Yes (16 kb/s)
–
–
300 bd
–
–
–
–
–
Yes
–
–
Yes
–
–
–
–
–
Yes
–
–
Yes
Yes
Yes
Yes
Yes
Yes
Yes
–
–
Yes
–
–
Yes
Yes
Yes
The MPU will run at 7/8 of the crystal clock rate in BROWNOUT mode. This permits the UARTs to be
operated at 300 bd. In this mode, the MPU clock has substantial short-term jitter.
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 the zero state disabling both the ADC
and the CE. When PLL_OK falls, the CE program counter is cleared immediately and all FIR processing
halts.
Figure 21 shows the functional blocks active in BROWNOUT mode.
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