MAX814 Maxim, MAX814 Datasheet - Page 7

• Manufacturer Part Number: MAX814
• Description: 1% Accuracy / Low-Power / +3V and +5V P Supervisory Circuits
• Manufacturer: Maxim

The MAX814/MAX815/MAX816 are high-accuracy, low-
power microprocessor (µP) supervisory circuits. They
have µP-reset, watchdog-timer, and power-fail func-
tions. Typical applications illustrating their similarities
and differences are shown in Figures 1, 2, and 3.
Figures 4, 5, and 6 show the block diagrams of these
parts.
_______________Detailed Description
______________________________________________________________Pin Description
*Reset Threshold Voltage is determined by part number suffix: K = 4.80V, L = 4.70V, N = 4.55V, T = 3.03V.
MAX814
—
—
—
—
1
2
3
4
5
6
7
8
MAX815
PIN
—
—
—
—
_______________________________________________________________________________________
±1% Accuracy, Low-Power, +3V and +5V
1
2
3
4
5
6
7
8
MAX816
—
—
—
—
1
2
3
4
5
6
7
8
LOW LINE
RESET IN
RESET
RESET
NAME
WDO
GND
PFO
WDI
V
MR
PFI
CC
Manual-Reset Input. Triggers a reset when pulled below 1.10V. This active-
low input has an internal 150µA pull-up current to V
with CMOS logic or shorted to GND with a switch or transistor.
Positive Power-Supply Input. When V
voltage*, RESET is low, and remains low for a minimum of 140ms after
it rises above the threshold.
Positive Power-Supply Input. On the MAX816, RESET is controlled by
RESET IN, not V
Ground
Power-Fail Input. The PFI threshold voltage is 1.70V on the MAX816 and on
MAX814/MAX815 parts with the T suffix. It is 2.50V on MAX814/MAX815
parts with K, L, and N suffixes. Connect PFI to GND or V
Power-Fail Output. When PFI is below its threshold, PFO is low;
otherwise it is high.
Watchdog CMOS Input. If WDI remains high or low for more than 1.56sec,
the watchdog timer times out, and WDO goes low. The timer is reset to
zero on each WDI transition.
Low-Line Output. Normally high, LOW LINE goes low when V
above the reset threshold. It returns high as soon as V
low-line threshold.
Reset Comparator Input. Reference is 1.70V. When RESET IN is below
1.70V, RESET is low, and remains low for a minimum of 140ms after it rises
above the reference.
Reset Output. Normally high, active low. Controlled by MR and reset
comparator.
Watchdog Output. Normally high, WDO goes low whenever the V
threshold comparator input voltage is low or when the watchdog timer
times out. There is no appreciable delay going either direction when the
V
Reset Output. Active high. The inverse of RESET.
CC
threshold comparator toggles.
µP Supervisory Circuits
CC
.
FUNCTION
CC
is below the reset threshold
CC
, and can be driven
CC
CC
rises above the
when not used.
CC
falls 60mV
CC
reset
7