71M6521DE Datasheet, PDF(51/107 Page) Teridian Semiconductor Corporation

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71M6521DE Datasheet, PDF (51/107 Pages) Teridian Semiconductor Corporation – Energy Meter IC

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71M6521DE/DH/FE Data Sheet

Circuit Function

CE Data RAM

FIR

Analog circuits:

PLL, ADC, VREF, BME etc

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

RAM Read and Write

Wakeup Timer

Oscillator and RTC

DRAM data preservation

V3P3D voltage output pin

System Power

MISSION

Yes

4.92MHz

(from PLL)

Yes

Battery Power (Non-volatile Supply)

BROWNOUT

LCD

SLEEP

Yes

28.672kHz

(7/8 of 32768Hz)

Yes

Yes (8kb/s)

Yes (16kb/s)

Yes

Table 60: Available Circuit Functions (âââ means ânot 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.

Rev 2

Page: 51 of 107

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