I2C-CPEV National Semiconductor, I2C-CPEV Datasheet - Page 23

• Manufacturer Part Number: I2C-CPEV
• Description: BOARD INTERFACE USB I2C
• Manufacturer: National Semiconductor

Specifications of I2C-CPEV

• Main Purpose: Interface, USB to I²C
• Utilized Ic / Part: COP8CBE9
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -

10.0 Functional Description
10.7.1 External Reset
The RESET input, when pulled low, initializes the device.
The RESET pin must be held low for a minimum of one
instruction cycle to guarantee a valid reset.
RESET may also be used to cause an exit from the HALT
mode.
A recommended reset circuit for this device is shown in
Figure 9.
(Continued)
WATCHDOG (if enabled):
The device comes out of reset with both the WATCHDOG
logic and the Clock Monitor detector armed, with the
WATCHDOG service window bits set and the Clock Moni-
tor bit set. The WATCHDOG and Clock Monitor circuits
are inhibited during reset. The WATCHDOG service win-
dow bits, being initialized high, default to the maximum
WATCHDOG service window of 64k T0 clock cycles. The
Clock Monitor bit being initialized high will cause a Clock
Monitor error following reset if the clock has not reached
the minimum specified frequency at the termination of
reset. A Clock Monitor error will cause an active low error
output on pin G1. This error output will continue until
16–32 T0 clock cycles following the clock frequency
reaching the minimum specified value, at which time the
G1 output will go high.
FIGURE 9. Reset Circuit Using External Reset
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10.7.2 On-Chip Brownout Reset
When enabled, the device generates an internal reset as
V
voltage (V
the Idle Timer is preset with 00Fx (240–256 t
reaches a value greater than V
counting down. Upon underflow of the Idle Timer, the internal
reset is released and the device will start executing instruc-
tions. This internal reset will perform the same functions as
external reset. Once V
Timer time-out takes place, instruction execution begins and
the Idle Timer can be used normally. If, however, V
below the selected V
the Idle Timer is preset with 00Fx. The device now waits until
V
functional operation of the device, at frequency, is guaran-
teed down to the V
CC
CC
is greater than V
rises. While V
bor
), the device is held in the reset condition and
bor
CC
bor
bor
CC
level.
is less than the specified brownout
, an internal reset is generated, and
and the countdown starts over. The
is above the V
bor
, the Idle Timer starts
bor
and this initial Idle
C
). When V
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CC
drops
CC