The LX7001 is an improved
undervoltage sensing circuit specifically designed for use as a reset
controller in microprocessor-based
systems. Today's complex miniaturized
systems present difficult challanges to
the system designer such as overcoming spurious noise problems. The
LX7001 is optimized for systems that
must be tolerant of high-speed power
supply glitches caused by high-speed
logic transitions and similar switching
phenomena. The LX7001 offers a
unique stage that couples glitch
immunity with a micropower, ultrastable band-gap reference for precision sensing of undervoltage conditions. It offers the designer an
NOTE: For current data & package dimensions, visit our web site: http://www.linfinity.com.
economical, space-efficient solution
for low supply voltage detection
when used in combination with a
single pull-up resistor. Adding one
capacitor offers the functionality of a
programmable delay time after power
returns. Additionally, the LX7001
offers excellent temperature stability.
A high-quality trimmed voltage
reference and bias circuit permit very
accurate and repeatable undervoltage
sensing. The remaining blocks
consist of a comparator with hysteresis, high current clamping diode and
open collector output stage capable
of sinking up to 60mA. The
LX7001's RESET output is specified to
be fully functional at VIN=1V.
Storage Temperature Range ...................................................................... -65°C to 150°C
Lead Temperature (Soldering, 10 seconds) ............................................................. 300°C
Note 1. Values beyond which damage may occur. All voltages are specified with respect to
ground, and all currents are positive into the specified terminal.
THERMAL DATA
DM PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
LP PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
Y PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
Junction Temperature Calculation: TJ = TA + (PD x θJA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board system.
All of the above assume no ambient airflow
Note 2. Range over which the device is functional.
Symbol
IN
OUT
F
Recommended Operating Conditions
Min.Typ.Max.
110V
10V
50mA
070°C
-2585°C
-55125°C
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply over the operating ambient temperatures of 0°C ≤ TA ≤ 70°C for the LX7001C,
-40°C ≤ TA ≤ 85°C for the LX7001I, and -55°C ≤ TA ≤ 125°C for the LX7001M. Low duty cycle pulse testing techniques are used which maintains
junction and case temperatures equal to the ambient temperature.)
A time delayed reset can be accomplished with the addition of C
For systems with extremely fast power supply rise times (< 500ns) it
is recommended that the RC
V
is the microprocessor reset input threshold.
TH(MPU)
time constant be greater than 5.0µs.
DLY
RESET
R
C
DLY
MICROPROCESSOR
CIRCUIT
DLY
1
t
DLY
= R C
DLY
In
FIGURE 15. — VOL TAGE MONITOR.FIGURE 16. — MOSFET LOW VOLTAGE GATE DRIVE PROTECTION.
1 -
V
TH(MPU)
V
IN
FIGURE 14. — SWITCHING THE LOAD OFF WHEN
BATTERY REACHES BELOW 4.3V.
V
IN
RESET
LOAD
.
1.2 V
REF
POWER
SUPPLY
V
IN
1.2 V
V
CC
1.0k
RESET
REF
4.3V
V
IN
1.2 V
REF
270
RESET
R
L
SMP60N03-10
Overheating of the logic level power MOSFET due to insufficient gate
voltage can be prevented with the above circuit. When the input signal is
below the 4.3 volt threshold of the LX7001C, its output grounds the gate
of the L2 MOSFET.
Comparator hysteresis can be increased with the addition of resistor RH. The
hysteresis equation has been simplified and does not account for the change of
input current IIN as VCC crosses the comparator threshold. An increase of the
lower threshold ∆V
4.59V. The equations are accurate to ±10% with RH less than 150Ω and R
between 1.5kΩ and 10kΩ.
PRODUCTION DATA - Information contained in this document is proprietary to LinFinity, and is current as of publication date. This document
may not be modified in any way without the express written consent of LinFinity. Product processing does not necessarily include testing of
all parameters. Linfinity reserves the right to change the configuration and performance of the product and to discontinue product at any time.
9
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