EM78156EAS EMC [ELAN Microelectronics Corp], EM78156EAS Datasheet - Page 29

• Manufacturer Part Number: EM78156EAS
• Description: 8-Bit Microcontroller with MASK ROM
• Manufacturer: EMC [ELAN Microelectronics Corp]

Product Specification (V1.3) 07.29.2004
(This specification is subject to change without further notice)
4.8 CODE Option Register
4.9 Power On Considerations
The EM78156E has a CODE option word that is not a part of the normal program
memory. The option bits cannot be accessed during normal program execution.
Bit 0 (LVDD):
Bit 1 (CLK):
Bit 2 (/ENWDT): Watchdog timer enable bit.
Bit 3 (HLF):
This bit will affect system oscillation only when Bit4(MS) is “1”. When MS is”0”, HLF
must be “0”.
Bit 4 (MS):
Bit 5:
Any microcontroller is not guaranteed to start to operate properly before the power
supply stays at its steady state.
EM78156E POR voltage range is 1.2V~1.8V. Under customer application, when
power is OFF, Vdd must drop to below 1.2V and remains OFF for 10us before power
can be switched ON again. This way, the EM78156E will reset and work normally. The
LVDD
Bit0
The transient point of system frequency between HXT and LXY is around 400 KHz.
Levels of the Operating Voltage.
0: Operating Voltage 2.3V ~ 5.5V, non-power saving.
1: Operating Voltage 4V ~ 5.5V, power saving.
Instruction period option bit.
0: two oscillator periods.
1: four oscillator periods.
Refer to the section on Instruction Set.
0: Enable
1: Disable
XTAL frequency selection
0: XTAL2 type (low frequency, 32.768KHz)
1: XTAL1 type (high frequency)
Oscillator type selection.
0: RC type
1: XTAL type (XTAL1 and XTAL2)
Reserved.
The bit is set to “1” all the time.
CLK
Bit1
/ENWDT
Bit2
NOTE
8-Bit Microcontroller with MASK ROM
Bit3
HLF
Bit4
MS
EM78156E
Bit5
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