LM3710XKMM-463/NOPB National Semiconductor, LM3710XKMM-463/NOPB Datasheet - Page 11

• Manufacturer Part Number: LM3710XKMM-463/NOPB
• Description: IC MPU SUPERVISOR 4.63V 10MSOP
• Manufacturer: National Semiconductor
• Type: Simple Reset/Power-On Resetr

Specifications of LM3710XKMM-463/NOPB

• Number Of Voltages Monitored: 1
• Output: Push-Pull, Totem Pole
• Reset: Active Low
• Reset Timeout: 20 ms Minimum
• Voltage - Threshold: 4.63V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Number Of Elements: 1
• Monitored Voltage 1 (typ): 1 to 5.5V
• Battery Backup Switching: No
• Watchdog Timer: Yes
• Chip Enable Signals: No
• Reset Active Time: 28ms(Typ)ms
• Manual Reset: Yes
• Package Type: MSOP
• Operating Supply Voltage (min): 1V
• Operating Supply Voltage (max): 5.5V
• Reset Threshold Voltage (max): 4.65V
• Reset Threshold Voltage (min): 4.6V
• Family Name: LM3710
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Power Fail Detection: Yes
• Mounting: Surface Mount
• Pin Count: 10
• Supply Current: 0.05mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM3710XKMM-463; LM3710XKMM-463TR

Circuit Information
RESET OUTPUT
The Reset input of a µP initializes the device into a known
state. The LM3710/LM3711 microprocessor supervisory cir-
cuits assert a forced reset output to prevent code execution
errors during power-up, power-down, and brownout condi-
tions.
RESET is guaranteed valid for V
ceeds the reset threshold, an internal timer maintains the
output for the reset timeout period. After this interval, reset
goes high. The LM3710 offers an active-low RESET; The
LM3711 offers an active-high RESET.
Any time V
during a brownout), the reset activates. When V
rises above the reset threshold, the internal timer starts.
Reset holds until V
than the reset timeout period. After this time, reset releases.
The Manual Reset input (MR) will initiate a forced reset also.
See the Manual Reset Input section.
RESET THRESHOLD
The LM3710/LM3711 family is available with a reset voltage
of 3.08V. Other reset thresholds in the 2.20V to 5.0V range,
in steps of 10 mV, are available; contact National Semicon-
ductor for details.
MANUAL RESET INPUT (MR)
Many µP-based products require a manual reset capability,
allowing the operator to initiate a reset. The MR input is fully
debounced and provides an internal 56 kΩ pull-up. When the
MR input is pulled below V
reset is asserted after a typical delay of 12 µs. Reset remains
active as long as MR is held low, and releases after the reset
timeout period expires after MR rises above V
with digital logic to assert or to daisy chain supervisory
circuits. It may be used as another low-line comparator by
adding a buffer.
POWER-FAIL COMPARATOR (PFI/PFO)
The PFI is compared to a 1.225V internal reference, V
PFI is less than V
The power-fail comparator signals a falling power supply,
and is driven typically by an external voltage divider that
senses either the unregulated supply or another system
supply voltage. The voltage divider generally is chosen so
the voltage at PFI drops below V
before the main supply voltage drops below the reset thresh-
old, providing advanced warning of a brownout.
CC
drops below the reset threshold (such as
PFT
CC
, the Power Fail Output PFO drops low.
exceeds the reset threshold for longer
MRT
(1.225V) for more than 25 µs,
CC
PFT
>
several milliseconds
1V. Once V
MRT
. Use MR
CC
CC
PFT
again
ex-
. If
11
The voltage threshold is set by R
as follows:
Note this comparator is completely separate from the rest of
the circuitry, and may be employed for other functions as
needed.
LOW-LINE OUTPUT (LLO)
The low-line output comparator is typically used to provide a
non-maskable interrupt to a µP when V
monitors V
(typically 1.02 • V
WATCHDOG TIMER INPUT (WDI)
The watchdog timer input monitors one of the microproces-
sor’s output lines for activity. Each time a transition occurs on
this monitored line, the watchdog counter is reset. However,
if no transition occurs and the timeout period is reached, the
LM3710/LM3711 assumes that the microprocessor has
locked up and the reset output is activated.
WDI is a high impedance input.
SPECIAL PRECAUTIONS FOR THE MICRO SMD
PACKAGE
As with most integrated circuits, the LM3710 and LM3711
are sensitive to exposure from visible and infrared (IR) light
radiation. Unlike a plastic encapsulated IC, the micro SMD
package has very limited shielding from light, and some
sensitivity to light reflected from the surface of the PC board
or long wavelength IR entering the die from the side may be
experienced. This light could have an unpredictable affect on
the electrical performance of the IC. Care should be taken to
shield the device from direct exposure to bright visible or IR
light during operation.
MICRO SMD MOUNTING
The micro SMD package requires specific mounting tech-
niques which are detailed in National Semiconductor Appli-
cation Note AN-1112. Referring to the section Surface
Mount Technology (SMT) Assembly Considerations, it
should be noted that the pad style which must be used with
the 9-pin package is the NSMD (non-solder mask defined)
type.
For best results during assembly, alignment ordinals on the
PC board may be used to facilitate placement of the micro
SMD device.
CC
and goes low when V
RST
) with hysteresis of 0.0032 • V
1
and R
CC
CC
2
begins falling. LLO
falls below V
and is calculated
www.national.com
RST
LLOT
.