ace1001 Fairchild Semiconductor, ace1001 Datasheet - Page 27

• Manufacturer Part Number: ace1001
• Description: Arithmetic Controller Engine Acex ?for Low Power Applications
• Manufacturer: Fairchild Semiconductor

ACE1001 Product Family Rev. B.1
12.0 RESET block
When a RESET sequence is initiated, all I/O registers will be reset
setting all I/Os to high-impedence inputs. The system clock is
restarted after the required clock start-up delay. A reset is gener-
ated by any one of the following three conditions:
• Power-on Reset (as described in Section 13.0)
• Brown-out Reset (as described in Section 11.1)
• Watchdog Reset (as described in Section 7.0)
13.0 Power-On-Reset
The Power-On Reset (POR) circuit is guaranteed to work if the
rate of rise of V
was designed to respond to fast low to high transitions between 0V
and V
the next power-up sequence. In applications where 1) the V
is slower than 10ms/1 volt or 2) V
next power-up sequence the external reset option should be used.
(The external reset option is not available in the ACE1001 but is
Table 15: CMODE[0:1] Bit Definition
Figure 25: BOR and POR Circuit Relationship Diagram (see AC Electrical Characteristics)
CC
. The circuit will not work if V
CMODE[0]
V CC (Pin 8)
CC
0
1
0
1
is no slower than 10ms/1volt. The POR circuit
(Pin 7)
BOR
POR
output
output
CC
does not drop to 0v before the
CC
output
POR
does not drop to 0V before
V CC
V CC
V CC
5.0V
1.8V
1.75
0
0
0
0
CMODE[1]
V CC
V CC
0
0
1
1
BOR Output
Time
CC
rise
27
available in the ACE1101 and ACE1202 product families.)
14.0 CLOCK
The ACEx microcontroller has an on-board oscillator trimmed to
a frequency of 2MHz who is divided down by two yielding a 1MHz
frequency.(See AC Electrical Characteristics.) Upon power-up,
the on-chip oscillator runs continuously unless entering HALT
mode or using an external clock source. (See Figure 26.)
If required, an external oscillator circuit may be used depending on
the states of the CMODE bits of the initialization register. (See
Table 15) When the device is driven using an external clock, the
clock input to the device (G1/CKI) can range between DC to
4MHz. For external crystal configuration, the output clock (CKO)
is on the G0 pin. If an external crystal or RC is used, to yield the
corresponding instruction clock the input frequency is internally
divided down by four. If the device is configured for an external
square clock, it will not be divided.
POR Output
Pulse
(14-Pin Only)
Internal 1 MHz clock
External square clock
External crystal/resonator
External RC clock
External
Reset
Pin
A
Clock Type
B
Reset
circuit
output
The Reset circuit will trigger
when inputs A or B transition
from High to Low. At that time
the Global Reset signal will go
high which will reset all controller
logic. The Global Reset will go
high and stay high for around 1µs.
Global Reset
to Logic
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