Rainbow Electronics MAX16055 - Manual (Page 8)

Manual-Reset Input (
MR)
Many µP-based products require manual-reset capabil-
ity. 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 20k
Ω pullup resistor to IN1.
Connect a normally open momentary switch from MR to
GND to create a manual-reset function. Connect a
0.1µF capacitor from MR to GND to provide additional
noise immunity when driving MR from long cables or
when the device is used in a noisy environment.
Tolerance (TOL)
The MAX16055 features an adjustable threshold toler-
ance. Connect TOL to GND to set the threshold volt-
ages 5% below the nominal value. Connect TOL to IN1
to set the threshold voltages 10% below the nominal
value. See the
Electrical Characteristics table. Do not
leave TOL unconnected.
Applications Information
Unused Inputs
Connect unused monitor inputs to a supply voltage
higher than the specified threshold voltage. Connect a
100k
Ω resistor between an unused adjustable input
and IN1 to limit the bias current. Use IN1 for normal
operation (device power supply). Do not connect
unused monitor inputs to ground. Do not leave unused
monitor inputs unconnected.
Reset Output Pullup Resistor
When connecting a pullup resistor from RESET to a
voltage rail lower than the voltage on IN1, the internal
70µA pullup current flows through the pullup resistor,
causing the voltage at RESET to be higher than the volt-
age rail when RESET is deasserted. Ensure that the
value of the pullup resistor is low enough that the volt-
age rise does not cause problems.
Power-Supply Bypassing and Grounding
IN1 powers the MAX16055. Connect a 0.1µF bypass
capacitor from IN1 to ground. All monitored inputs are
immune to short supply transients. Add bypass capaci-
tors from IN2–IN6 to GND to improve noise immunity.
MAX16055
Ultra-Small, Hex Voltage,
Microprocessor Supervisor
8 _______________________________________________________________________________________
V TH + V HYST
V IN1
V IN2
V IN3
V IN5
V IN6
RESET
V IN4
t RP t RP BEGINS
WHEN THE LAST
SUPPLY EXCEEDS
ITS V
TH + V HYST
Figure 4. RESET Output with Various Input Voltages
R1
V TH
R1 = R2
(
-1
) V INTH
V TH
V INTH
R2
MAX16055
Figure 5. Setting the Adjustable Threshold