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MAX690TESA+ 数据手册 - Maxim Integrated（美信）
制造商:
Maxim Integrated（美信）
分类:
电源监控芯片
封装:
SOIC-8
描述:
MAXIM INTEGRATED PRODUCTS MAX690TESA+ 芯片, 微处理器监控器, 5.5V, NSOIC-8
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MAX690TESA+数据手册
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Detailed Description
Reset Output
A microprocessor’s (µP’s) reset input starts the µP in a
known state. These µP supervisory circuits assert reset
to prevent code execution errors during power-up, power-
down, brownout conditions, or a watchdog timeout.
RESET is guaranteed to be a logic low for 0V < V
CC
<
V
RST
, provided that VBATT is greater than 1V. Without a
backup battery, RESET is guaranteed valid for V
CC
> 1V.
Once V
CC
exceeds the reset threshold, an internal timer
keeps RESET low for the reset timeout period; after this
interval, RESET goes high (Figure 2).
If a brownout condition occurs (V
CC
dips below the reset
threshold), RESET goes low. Each time RESET is assert-
ed, it stays low for the reset timeout period. Any time V
CC
goes below the reset threshold, the internal timer restarts.
The watchdog timer can also initiate a reset. See the
Watchdog Input section.
The MAX804_/MAX805_ active-high RESET output is
open drain, and the inverse of the MAX690_/MAX704_/
MAX802_/MAX806_ RESET output.
Reset Threshold
The MAX690T/MAX704T/MAX805T are intended for 3.3V
systems with a ±5% power-supply tolerance and a 10%
system tolerance. Except for watchdog faults, reset will
not assert as long as the power supply remains above
3.15V (3.3V - 5%). Reset is guaranteed to assert before
the power supply falls below 3.0V.
The MAX690S/MAX704S/MAX805S are designed for
3.3V ±10% power supplies. Except for watchdog faults,
they are guaranteed not to assert reset as long as the
supply remains above 3.0V (3.3V - 10%). Reset is
guaranteed to assert before the power supply falls below
2.85V (V
CC
- 14%).
The MAX690R/MAX704R/MAX805R are optimized for
monitoring 3.0V ±10% power supplies. Reset will not
occu
r
until V
CC
falls below 2.7V (3.0V - 10%), but is
guaranteed to occur before the supply falls below 2.59V
(3.0V - 14%).
The MAX802R/S/T, MAX804R/S/T, and MAX806R/S/T are
respectively similar to the MAX690R/S/T, MAX805R/S/T,
and MAX704R/S/T, but with tightened reset and power-fail
threshold tolerances.
PIN
NAME FUNCTION
MAX690
MAX802
MAX704
MAX806
MAX804
MAX805
1 1 1 V
OUT
Supply Output for CMOS RAM. When V
CC
is above the reset threshold, V
OUT
is
connected to V
CC
through a p-channel MOSFET switch. When V
CC
falls below V
SW
and
VBATT, VBATT connects to V
OUT
. Connect to V
CC
if no battery is used.
2 2 2 V
CC
Main Supply Input
3 3 3 GND Ground
4 4 4 PFI
Power-Fail Input. When PFI is less than V
PFT
or when V
CC
falls below V
SW
, PFO goes
low; otherwise, PFO remains high. Connect to ground if unused.
5 5 5 PFO
Power-Fail Output. When PFI is less than V
PFT
, or V
CC
falls below V
SW
, PFO goes low;
otherwise, PFO remains high. Leave open if unused.
6 — 6 WDI
Watchdog Input. If WDI remains high or low for 1.6s, the internal watchdog timer runs out
and reset is triggered. The internal watchdog timer clears while reset is asserted or when
WDI sees a rising or falling edge. The watchdog function cannot be disabled.
— 6 — MR
Manual Reset Input. A logic low on MR asserts reset. Reset remains asserted as long as
MR is low and for 200ms after MR returns high. This active-low input has an internal
70µA pullup current. It can be driven from a TTL or CMOS logic line, or shorted to ground
with a switch. Leave open if unused.
7 7 — RESET
Active-Low Reset Output. Pulses low for 200ms when triggered, and stays low whenever
V
CC
is below the reset threshold or when MR is a logic low. It remains low for 200ms
after either V
CC
rises above the reset threshold, the watchdog triggers a reset, or MR
goes from low to high.
— — 7 RESET Active-High, Open-Drain Reset Output is the inverse of RESET.
8 8 8 VBATT
Backup-Battery Input. When V
CC
falls below V
SW
and VBATT, V
OUT
switches from V
CC
to VBATT. When V
CC
rises above the reset threshold, V
OUT
reconnects to V
CC
. VBATT
may exceed V
CC
. Connect to V
CC
if no battery is used.
MAX690T/S/R, MAX704T/S/R,
MAX802T/S/R, MAX804−MAX806T/S/R
3.0V/3.3V Microprocessor
Supervisory Circuits
www.maximintegrated.com
Maxim Integrated
│
6
Pin Description
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