em78p156n ELAN Microelectronics Corp, em78p156n Datasheet - Page 26

• Manufacturer Part Number: em78p156n
• Description: 8-bit Micro-controller
• Manufacturer: ELAN Microelectronics Corp

The EM78P156N can be operated in three different oscillator modes, such as External RC oscillator mode
(ERC), High XTAL oscillator mode (HXT), and Low XTAL oscillator mode (LXT). User can select one of them
by programming OSC and HLF in the CODE option register. Table 6 depicts how these three modes are
defined.
The up-most limited operation frequency of crystal/resonator on the different VDDs is listed in Table 7.
This specification is subject to change without prior notice.
4.7 Oscillator
1. Oscillator Modes
/IRQn
<Note> 1. X, Don’t care
Table 8 Oscillator Modes Defined by OSC and HLP
ERC(External RC oscillator mode)
HXT(High XTAL oscillator mode)
LXT(Low XTAL oscillator mode)
VCC
/RESET
2.The transient point of system frequency between HXT and LXY is around 400 KHz.
D
RF
CLK
Mode
P
R
C
L
Q
Q
_
Fig. 10 Interrupt Input Circuit
IOCF
26
Q
Q
_
IOCFRD
RFWR
OSC
P
R
C
L
CLK
0
1
1
D
RFRD
IOCFWR
IRQn
IRQm
HLF
*X
1
0
HLP
*X
*X
0
EM78P156N
IOD
ENI/DISI
OTP ROM
07.29.2004 (V1.2)
INT