MAX6315US33D4-T Maxim Integrated, MAX6315US33D4-T Datasheet - Page 4

• Manufacturer Part Number: MAX6315US33D4-T
• Description: Supervisory Circuits
• Manufacturer: Maxim Integrated
• Series: MAX6315r

Specifications of MAX6315US33D4-T

• Number Of Voltages Monitored: 1
• Monitored Voltage: 1 V to 5.5 V
• Undervoltage Threshold: 3.24 V
• Overvoltage Threshold: 3.36 V
• Output Type: Active Low, Open Drain
• Manual Reset: Resettable
• Watchdog: No Watchdog
• Battery Backup Switching: No Backup
• Power-up Reset Delay (typ): 1570 ms
• Supply Voltage - Max: 5.5 V
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Package / Case: SOT-143
• Chip Enable Signals: No
• Maximum Power Dissipation: 320 mW
• Minimum Operating Temperature: - 40 C
• Power Fail Detection: No
• Supply Current (typ): 5 uA
• Supply Voltage - Min: 1 V

A microprocessor’s (µP’s) reset input starts the µP in a
known state. The MAX6315 asserts reset to prevent
code-execution errors during power-up, power-
down, or brownout conditions. RESET is guaranteed to
be a logic-low for V
Characteristics table). Once V
threshold, the internal timer keeps reset asserted for the
reset timeout period (t
goes high. If a brownout condition occurs (monitored
voltage dips below its programmed reset threshold),
RESET goes low. Any time V
threshold, the internal timer resets to zero and RESET
goes low. The internal timer starts when V
above the reset threshold, and RESET remains low for
the reset timeout period.
The MAX6315’s RESET output structure is a simple
open-drain n-channel MOSFET switch. Connect a pull-
up resistor to any supply in the 0V to +6V range. Select
a resistor value large enough to register a logic low
when RESET is asserted (see the Electrical
Characteristics table), and small enough to register a
logic high while supplying all input current and leakage
paths connected to the RESET line. A 10kΩ pullup is
sufficient in most applications.
Often, the pull-up connected to the MAX6315’s RESET
output will connect to the supply voltage monitored at
the IC’s V
open-drain output to level-shift from the monitored sup-
ply to reset circuitry powered by some other supply
(Figure 1). This is one useful feature of an open-drain
output. Keep in mind that as the MAX6315’s V
decreases below 1V, so does the IC’s ability to sink
current at RESET. Finally, with any pullup, RESET will
be pulled high as V
where this occurs depends on the pull-up resistor value
and the voltage to which it connects (see the Electrical
Characteristics table).
Many µP-based products require manual-reset capa-
bility, allowing the operator, a test technician, or exter-
nal logic circuitry to initiate a reset. A logic low on MR
asserts reset. Reset remains asserted while MR is low,
and for the reset active timeout period after MR
returns high.
Open-Drain SOT µP Reset Circuit
4
_______________Detailed Description
_______________________________________________________________________________________
CC
pin. However, some systems may use the
CC
CC
decays toward 0V. The voltage
RP
); after this interval RESET
> 1V (see the Electrical
CC
Manual-Reset Input
CC
dips below the reset
exceeds the reset
Reset Output
CC
returns
CC
MR has an internal 63kΩ pullup resistor, so it can be
left open if not used. Connect a normally open momen-
tary 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 environment, connecting a 0.1µF capacitor
from MR to ground provides additional noise immunity.
In addition to issuing a reset to the µP during power-up,
power-down, and brownout conditions, these devices
are relatively immune to short-duration negative-going
transients (glitches). The Typical Operating Character-
istics show the Maximum Transient Duration vs. Reset
Threshold Overdrive, for which reset pulses are not
generated. The graph was produced using negative-
going pulses, starting at V
the programmed reset threshold by the magnitude indi-
cated (reset threshold overdrive). The graph shows the
maximum pulse width that a negative-going V
sient may typically have without causing a reset pulse
to be issued. As the transient amplitude increases (i.e.,
goes farther below the reset threshold), the maximum
allowable pulse width decreases. A 0.1µF bypass
capacitor mounted close to V
transient immunity.
Figure 1. MAX6315 Open-Drain RESET Output Allows Use
with Multiple Supplies
__________Applications Information
MR
MAX6315
+3.3V
Negative-Going V
V
CC
GND
RESET
10kΩ
RST
CC
max and ending below
provides additional
CC
5V SYSTEM
+5.0V
Transients
CC
tran-