MAX805RC/D Maxim Integrated, MAX805RC/D Datasheet - Page 6

• Manufacturer Part Number: MAX805RC/D
• Description: Supervisory Circuits
• Manufacturer: Maxim Integrated
• Series: MAX690R, MAX690S, MAX690T, MAX704R, MAX704S, MAX704T, MAX802, MAX802R, MAX802S, MAX802T, MAX804, MAX804R, MAX804S, MAX804T, MAX805, MAX805R, MAX805S, MAX805T, MAX806, MAX806R, MAX806S, MAX806Tr

Specifications of MAX805RC/D

• Number Of Voltages Monitored: 1
• Monitored Voltage: 4.65 V
• Output Type: Active High, Push-Pull
• Manual Reset: Not Resettable
• Watchdog: Watchdog
• Battery Backup Switching: Backup
• Supply Voltage - Max: 5.5 V
• Chip Enable Signals: No
• Power Fail Detection: Yes
• Supply Voltage - Min: 1.1 V

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.
–
V
a backup battery,
> 1V. Once V
internal timer keeps
period; after this interval,
If a brownout condition occurs (V
reset threshold),
is asserted, it stays low for the reset timeout period.
Any time V
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_
3.0V/3.3V Microprocessor Supervisory Circuits
R
6
_______________Detailed Description
______________________________________________________________Pin Description
—
MAX690
MAX802
RST
E
—
S
—
—
—
_______________________________________________________________________________________
1
2
3
4
5
6
7
8
, provided that VBATT is greater than 1V. Without
E
—
T
–
is guaranteed to be a logic low for 0V < V
MAX704
MAX806
CC
PIN
—
—
1
2
3
4
5
6
7
8
goes below the reset threshold, the
CC
–
R
—
–
R
E
—
—
MAX804
MAX805
exceeds the reset threshold, an
–
R
S
E
—
—
—
–
R
—
E
S
E
—
—
—
—
—
1
2
3
4
5
6
8
E
7
—
S
T
E
–
—
—
S
—
–
R
E
T
—
–
—
goes low. Each time
E
—
T
E
–
—
is guaranteed valid for V
T
–
S
–
R
output.
RESET
VBATT
—
NAME
—
V
GND
–
P
WDI
E
V
—
low for the reset timeout
E
–
—
PFI
M
—
OUT
F
—
CC
—
S
—
T
–
R
O
–
E
–
—
goes high (Figure 2).
T
–
CC
Supply Output for CMOS RAM. When V
connected to V
VBATT, VBATT connects to V
Main Supply Input
Ground
Power-Fail Input. When PFI is less than V
low; otherwise,
Power-Fail Output. When PFI is less than V
otherwise,
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.
Manual Reset Input. A logic low on
–
M
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.
Active-Low Reset Output. Pulses low for 200ms when triggered, and stays low whenever
V
either V
from low to high.
Active-High, Open-Drain Reset Output is the inverse of
Backup-Battery Input. When V
VBATT. When V
exceed V
—
Reset Output
CC
R
–
dips below the
is low and for 200ms after
is below the reset threshold or when
CC
CC
–
P
rises above the reset threshold, the watchdog triggers a reset, or
—
–
R
. Connect to V
—
F
—
E
O
—
–
CC
–
P
CC
S
—
—
CC
remains high. Leave open if unused.
F
—
E
CC
—
through a p-channel MOSFET switch. When V
O
<
–
T
–
rises above the reset threshold, V
remains high. Connect to ground if unused.
CC
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
The MAX690R/MAX704R/MAX805R are optimized for
monitoring 3.0V ±10% power supplies. Reset will not
occur until V
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.
OUT
if no battery is used.
CC
–
M
—
R
–
. Connect to V
falls below V
returns high. This active-low input has an internal
–
M
—
R
–
FUNCTION
CC
asserts reset. Reset remains asserted as long as
PFT
–
M
CC
—
is above the reset threshold, V
PFT
R
–
CC
or when V
is a logic low. It remains low for 200ms after
SW
falls below 2.7V (3.0V - 10%), but is
, or V
- 14%).
CC
and VBATT, V
if no battery is used.
CC
OUT
falls below V
CC
–
R
—
E
—
reconnects to V
falls below V
S
—
E
—
T
–
.
OUT
CC
Reset Threshold
SW
falls below V
switches from V
,
SW
–
P
—
OUT
F
CC
—
,
O
–
P
–
—
–
. VBATT may
M
F
—
—
goes low;
is
R
O
–
–
goes
SW
goes
CC
and
to