MAX16000 Datasheet, PDF (22/26 Pages) Maxim Integrated Products – Low-Voltage, Quad-/Hex-/Octal-Voltage μP Supervisors

Low-Voltage, Quad-/Hex-/Octal-Voltage
µP Supervisors
VTH + VTH_HYST
VIN
VTH
VTH + VTH_HYST
MARGIN
RESET
INTERNAL
RESET
SIGNAL
tRP
tRP
Figure 15. Margin Output Disable (MARGIN) Affect on RESET Outside t_RP
Reset Timeout Capacitor
The reset timeout period can be adjusted to accommo-
date a variety of µP applications from 50µs to 1.12s.
Adjust the reset timeout period (t_RP) by connecting a
capacitor (C_SRT) between SRT and GND. Calculate the
reset timeout capacitor as follows:
C_SRT (F)
=
t_RP (s) x I_SRT
V_{TH _ SRT}
Connect SRT to V_CC for a factory-programmed reset
timeout of 140ms (min).
Manual Reset Input (MR)
(MAX16001/MAX16002/
MAX16004–MAX16007)
Many µP-based products require manual reset capabil-
ity, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. A logic-low on MR
asserts RESET low. RESET remains asserted while MR
is low, and during the reset timeout period (140ms min)
after MR returns high. The MR input has an internal
20kΩ pullup resistor to V_CC, so it can be left uncon-
nected if not used. MR can be driven with TTL or
CMOS-logic levels, or with open-drain/collector out-
puts. Connect a normally open momentary switch from
MR to GND to create a manual reset function. External
debounce circuitry is not required. If MR is driven from
long cables or if the device is used in a noisy environ-
ment, connecting a 0.1µF capacitor from MR to GND
provides additional noise immunity.
Margin Output Disable (MARGIN)
MARGIN allows system-level testing while power sup-
plies are adjusted from their nominal voltages. Drive
MARGIN low to force RESET, WDO, and OUT_ high,
regardless of the voltage at any monitored input. The
state of each output does not change while MARGIN =
GND. The watchdog timer continues to run when
MARGIN is low, and if a timeout occurs, WDO/RESET
will assert t_MD after MARGIN is deasserted.
The MARGIN input is internally pulled up to V_CC. Leave
MARGIN unconnected or connect to V_CC if unused.
Power-Supply Bypassing
The MAX16000–MAX16007 operate from a 2.0V to 5.5V
supply. An undervoltage lockout ensures that the out-
puts are in the correct states when the UVLO is exceed-
ed. In noisy applications, bypass V_CC to ground with a
0.1µF capacitor as close to the device as possible. The
additional capacitor improves transient immunity. For
fast-rising V_CC transients, additional capacitance may
be required
22 ______________________________________________________________________________________