MAX6842GUKD2-T Maxim Integrated, MAX6842GUKD2-T Datasheet - Page 6

• Manufacturer Part Number: MAX6842GUKD2-T
• Description: Supervisory Circuits
• Manufacturer: Maxim Integrated
• Series: MAX6841, MAX6842, MAX6843, MAX6844, MAX6845r

Specifications of MAX6842GUKD2-T

• Number Of Voltages Monitored: 1
• Monitored Voltage: 0.9 V to 1.5 V
• Undervoltage Threshold: 1.08 V
• Overvoltage Threshold: 1.14 V
• Output Type: Active High, Active Low, Open Drain, Push-Pull
• Manual Reset: Resettable
• Watchdog: No Watchdog
• Battery Backup Switching: No Backup
• Power-up Reset Delay (typ): 0.15 ms
• Supply Voltage - Max: 1.8 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SOT-23
• Chip Enable Signals: No
• Maximum Power Dissipation: 571 mW
• Minimum Operating Temperature: - 40 C
• Power Fail Detection: No
• Supply Current (typ): 8.1 uA
• Supply Voltage - Min: 0.75 V

RESET IN decreases. The MAX6843/MAX6844/
MAX6845 assert a reset when the voltage at RESET IN
falls below the RESET IN threshold (V
leakage current at RESET IN allows for relatively large-
value resistors to be used, which reduces power
consumption. For example, for V
100kΩ, then R1 = 26.3kΩ.
The MAX6841–MAX6845 are relatively immune to short-
duration falling V
shows typical transient duration vs. reset comparator
overdrive, for which the MAX6841–MAX6845 do not
generate a reset pulse. The graph was generated using
a falling pulse applied to V
actual reset threshold and ending below it by the mag-
nitude indicated (reset comparator overdrive). The
graph indicates the maximum pulse width that a falling
V
As the magnitude of the transient increases (goes fur-
ther below the reset threshold), the maximum allowable
pulse width decreases. A 0.1µF bypass capacitor
mounted as close as possible to the V
additional transient immunity.
When V
push-pull RESET output no longer sinks current; it
becomes an open circuit. Therefore, high-impedance
CMOS-logic inputs connected to RESET can drift to
undetermined voltages. This presents no problem in
Ultra-Low-Voltage µP Reset Circuits and
Voltage Detectors
Figure 2. Maximum Transient Duration vs. Overdrive
6
CC
_______________________________________________________________________________________
transient can have without causing a reset pulse.
CC
600
550
500
450
400
350
300
250
200
150
100
falls below 0.55V, the MAX6841/MAX6843
1
Applications Information
Ensuring a Valid Reset Output
MAXIMUM TRANSIENT DURATION
RESET OCCURS ABOVE THIS LINE
CC
OVERDRIVE V
transients (glitches). Figure 2
vs. OVERDRIVE
V
CC
CC
10
TH
, starting 0.1V above the
- V
Falling Transients
CC-TH
CC
Down to V
(mV)
RSTIN
CC
= 0.9V, if R2 =
pin provides
100
). The low-
CC
= 0
most applications, because most µP and other circuitry
are inoperative with V
applications in which RESET must be valid down to 0,
adding a pulldown resistor to RESET causes any stray
leakage currents to flow to ground, holding RESET low
(Figure 3). R3’s value is not critical; 200kΩ is large
enough not to load RESET and small enough to pull
RESET to ground.
A 200kΩ pullup resistor to V
for the MAX6841/MAX6842/MAX6844 if push-pull
RESET is required to remain valid for V
Because the RESET output on the MAX6842/MAX6845
is open drain, these devices interface easily with µPs
that have bidirectional reset pins. Connecting the µP
supervisor’s RESET output directly to the µP’s RESET
pin with a single pullup resistor allows either device to
assert reset (Figure 4).
Figure 3.
Figure 4. Interfacing to Microprocessors with Bidirectional
Reset I/0
V
CC
MAX6845
MAX6842
RESET Valid to V
Interfacing to µPs with Bidirectional
V
GND
CC
RESET
MAX6843
MAX6841
CC
V
GND
CC
CC
lower than 0.55V. However, in
= 0
RESET
CC
is also recommended
R3
RESET
INPUT
CC
Reset Pins
≤ 0.75V.
V
GND
µP
CC