Datasheet

Using the MAX6842/MAX6845 Open-Drain
RESET Output with Multiple Supplies
Generally, the pullup connected to the MAX6842/
MAX6845 connects to the supply voltage being moni-
tored at the IC’s V
CC
pin. However, some systems use
the open-drain output to level-shift from the monitored
supply to reset circuitry powered by some other supply
(Figure 5). Note that as the MAX6842/MAX6845’s V
CC
decreases, so does the IC’s ability to sink current at
RESET. Also, with any pullup, RESET is pulled high as
V
CC
decays toward 0. The voltage where this occurs
depends on the pullup resistor value and the voltage to
which it is connected.
Chip Information
TRANSISTOR COUNT: 788
PROCESS: BiCMOS
MAX6841–MAX6845
Ultra-Low-Voltage µP Reset Circuits and
Voltage Detectors
_______________________________________________________________________________________ 7
Table 1. Threshold Suffix Guide
MAX6842
MAX6845
V
CC
RESET
GND
V
CC
RESET
GND
R
PULLUP
0.9V
µP
+5.0V
Figure 5. Using the MAX6842/MAX6845 Open-Drain RESET
Output with Multiple Supplies
SUFFIX RESET THRESHOLD (V)
I 1.388
H 1.313
G 1.110
F 1.050
E 0.833
D 0.788
Table 2. Active Timeout Period Guide
RESET ACTIVE TIMEOUT PERIOD (ms)
SUFFIX
MIN TYP MAX
D0 — 0.15 —
D1 1 1.5 2
D2 20 30 40
D3 140 210 280
D4 1120 1680 2240
Table 3. Standard Versions
DEVICE TOP MARK
MAX6841HUKD0 AEDR
MAX6841HUKD3 AEDS
MAX6841FUKD0 AEDP
MAX6841FUKD3 AEDQ
MAX6841DUKD0 AEDN
MAX6841DUKD3 AEDO
MAX6842HUKD0 AEDX
MAX6842HUKD3 AEDY
MAX6842FUKD0 AEDV
MAX6842FUKD3 AEDW
MAX6842DUKD0 AEDT
MAX6842DUKD3 AEDU
MAX6843UKD0 AEDZ
MAX6843UKD3 AEAV
MAX6844UKD0 AEEB
MAX6844UKD3 AEEC
MAX6845UKD0 AEAX
MAX6845UKD3 AEAY