SH3000EK SEMTECH [Semtech Corporation], SH3000EK Datasheet - Page 5

• Manufacturer Part Number: SH3000EK
• Description: Reset Management and Clock Management Support IC for Microcontrollers
• Manufacturer: SEMTECH [Semtech Corporation]

CPU Supervisor
manage the reset of the target processor, a low V
monitor (Brownout Detector), see Figure 1.
Management System to provide a more complete
system solution than stand-alone components.
reset output pins. Both are driven strong to the active
state and weak to the inactive state. This eliminates the
need for external pull-ups and allows various reset
sources to be connected together in a wire-OR
configuration. (This makes it simple to set up a manual
reset circuit.)
source of the reset to the system software.
Low V
V
threshold, programmable from 2.3 V to 4.3 V in average
steps of 33 mV, see Table 1.
Table 1. Programmable V
Parameter
VBO for min code
(000000)
VBO for max code
(111111)
Step resolution
Copyright ©2002-2005 Semtech Corporation
SYSTEM MANAGEMENT
DD
Temperature-
compensated
Reference
Lock Logic
Voltage
The SH3002 has two supervisory functions that
Both functions are integrated with the Clock
The SH3002 has both active high and active low
A set of flags in the register map indicates the
The SH3002 drives the reset pins active whenever
is below the value of V
DD
V
1
DD
Reset
4.40 V
2.30 V
Figure 1. CPU Supervisor --- Low V
Noise Filter
V
V
HIGH
LOW
6-bit Value
Threshold
D/A
Min
2.27
4.2
BO
BO
Values
, the brownout reset
Typ
2.3
4.3
33
Hysteresis
50mV
Initialization Logic
TYP
Max
2.33
4.4
Write-once
.
DD
R
ESET
Units
V
V
mV
DD
/ Brownout Detector, Watchdog, Reset logic & Drivers
32.768kH
PWR
5
OK
The default V
factory-programmed nonvolatile memory. It can be re-
programmed at any time or it can be permanently
protected from any changes by setting the V
or a write-protect flag.
reset signals are driven active. These outputs are
typically valid for a V
guaranteed to be valid for a V
stays above the level of (V
a small fixed amount of hysteresis, nominally 50 mV,
added to prevent nuisance reset activations (when V
slowly changes near the level of V
power glitching is present).
considered valid. In case of the initial power-up, the
reset is then driven inactive once 6 ms of valid power
have elapsed. In the case of brownout, the reset is
released after a delay of 6 ms (but no less than 12 ms
from the beginning of the brownout).
provides a fast-starting clock that is free of crystal start-
up time requirements. This gives the SH3002 an
advantage over most external reset circuits, which must
have a long reset pulse duration to accommodate long
and unpredictable crystal start-up times.
clock is available 2 ms before the reset signals are
negated, so that internal synchronous reset and
initialization of the target micro can proceed normally.
z
On power up both the active-high and active-low
The reset outputs remain active until V
At the level of (V
Such a fast reset is possible because the SH3002
The SH3002 guarantees that a valid and stable
Duration Timer
Reset Logic
U
NDERFLOW
Minimum
BO
&
value is loaded on power-up from the
1→0
DD
BO
SH3002 MicroBuddy™
level of at least 0.5 V, and
+ V
BO
HYST
V
V1.20
DD
+ V
DD
20
) the power supply is
R
level of 1.0 V.
HYST
ESET
K
BO
and some noise or
), where V
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20
K
DD
BO
rises and
Lock flag
HYST
From / To
Serial I/O
RST
N
11
10
RST
DD
is