em78p131a ELAN Microelectronics Corp, em78p131a Datasheet - Page 33

• Manufacturer Part Number: em78p131a
• Description: 8-bit Microcontroller With Otp Rom
• Manufacturer: ELAN Microelectronics Corp

Product Specification (V1.2) 09.16.2009
(This specification is subject to change without further notice)
5.9 Power
Any microcontroller is not guaranteed to start to operate properl
supply stabilizes at its steady state. Under customer
Vdd must drop to below 1.8V and remains OFF for 1
ON a
external reset circuit will work well if Vdd ca
However, under most
require
5.10 Programma
The Option word contains SUT0 and SUT1 which can be used to define the oscillator
set-up time. Theo
ceramic resonators, the lower the opera
may be required. Table 12 describes the values of the Oscillator Set-up Time.
5.11 External Power-on Reset Circuit
The circuit shown in Figure
5-14 implemen
RC to produce the reset
pulse. The pulse width (time
constant) should be
long enough for Vdd to reach
minimum operation voltage
This circuit is used when the
power s
time.
Since the current lea
should not be greate
The diode (D) acts as a short circuit at the moment of power down.
Bit 1 and Bit 0 (RCM1, RCM0): RC mode select bits
Bits 12~ 0: Customer’s ID code
Customer ID Register (Word
gain.
RCM 1
d to assist in solving
upply
1
1
0
0
This way
has a slow ris
ts
-on Consid
an external
retically, the range i
r than 40K. In this way, the /RE
, the E
kept
kage from the /RESET pin is
RCM 0
XXXXXXXXXXXXX
ca
1
0
1
0
ses where critical
Bit 12~Bit 0
ble Oscillator Set-up Tim
M78P131A w
.
e
the power-up proble
erations
2)
*Frequency (MHz)
s from
tion frequency is, the longer the Set-up
Fig 5-14 External Power-up Reset Circuit
ill reset and operate no
/RESET
applicat
455kHz
n rise a
VDD
4.5 ms to 72 ms. For
4
8
1
8-Bit Microcontroller with OTP ROM
ms.
± 5μA, it is recommended that R
ions are involved, extra devices are
t a very fast speed (50 ms or less).
SET pin voltage is held below 0.2V.
0µs before power can be switched
application, when power is OFF,
Rin
rmally. The extra
y before the power
e
C
R
most of crystal or
EM78P131A
time
D
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