78M6618-IMR View Datasheet(PDF) - Teridian Semiconductor Corporation

Part Name

Description

Manufacturer

78M6618-IMR

Octal Power and Energy Measurement IC

Teridian Semiconductor Corporation 

78M6618 Data Sheet

DS_6618_005

1.12 Real-Time Clock (RTC)

The RTC circuit is driven directly by the crystal oscillator. The RTC consists of a counter chain and output

registers. The counter chain consists of registers for seconds, minutes, hours, day of week, day of

month, month, and year (including leap years). See the 78M6618 Programmer’s Reference Manual for

more information regarding the use of the 78M6618 RTC.

1.13 Hardware Watchdog Timer

V3P3

V3P3 - 10mV

V3P3 -

400mV

V1

In addition to the basic watchdog timer included in the 80515 MPU, an

independent, robust, fixed-duration, watchdog timer (WDT) is included in

WDT dis- the device. It uses the crystal oscillator as its time base and must be

abled refreshed by the MPU firmware at least every 1.5 seconds. When not

refreshed on time the WDT overflows, and the part is reset as if the RESET

pin were pulled high, except that the IORAM bits will be maintained. 4096

Normal

operation,

WDT

oscillator cycles (or 125 ms) after the WDT overflow, the MPU will be

launched from program address 0x0000. Asserting ICE_E will deactivate

enabled

the WDT.

VBIAS

Battery

modes

The WDT can also be disabled by tying the V1 pin to V3P3. This also

deactivates V1 power fault detection. Since there is no method in firmware

to disable the crystal oscillator or the WDT, it is guaranteed that whatever

state the part might find itself in, upon watchdog overflow, the part will be

reset to a known state.

0V

Figure 3: Functions Defined by V1

1.14 Temperature Sensor

The device includes an on-chip temperature sensor for determining the temperature of the bandgap re-

ference. The primary use of the temperature data is to determine the magnitude of compensation required

to offset the thermal drift in the system. See the 78M6618 Programmer’s Reference Manual for more

information regarding the use of the 78M6618 Temperature Sensor.

1.15 General Purpose Digital I/O

The 78M6618 includes up to 19 pins of general-purpose digital I/O. When configured as inputs, these

pins are 5V compatible (no current-limiting resistors are needed). On reset or power-up, all DIO pins are

inputs until they are configured for the desired direction under MPU control. The Digital I/O pins can be

categorized as follows:

• DIO1/OPT_RX, DIO2/OPT_TX (2 pins) UART/DIO pin

• DIO3

(1 pin ) Dedicated DIO pin

• DIO4/SEG24 -- DIO11/SEG31 (8 pins) LCD/DIO pins

• DIO13/SEG33 -- DIO19/SEG39 (7 pins) LCD/DIO pins

• DIO43/SEG63

(1 pin ) LCD/DIO pin

10

Rev. 1.4

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