ICL7665AESA Maxim Integrated Products, ICL7665AESA Datasheet - Page 7

• Manufacturer Part Number: ICL7665AESA
• Description: Supervisory Circuits Integrated Circuits (ICs)
• Manufacturer: Maxim Integrated Products

Specifications of ICL7665AESA

• Number Of Voltages Monitored: 2
• Undervoltage Threshold: 1.275 V, 1.225 V
• Overvoltage Threshold: 1.325 V, 1.375 V
• Manual Reset: Not Resettable
• Watchdog: No Watchdog
• Supply Voltage (max): 16 V
• Supply Voltage (min): 2 V
• Supply Current (typ): 15 uA
• Maximum Power Dissipation: 471 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-8
• Minimum Operating Temperature: - 40 C
• Lead Free Status / Rohs Status: No

Figures 3, 4, and 5 show the three basic voltage detec-
tion circuits.
The simplest circuit, depicted in Figure 3, does not
have any hysteresis. The comparator trip-point formulas
can easily be derived by observing that the comparator
changes state when the V
nal resistors form a voltage divider that attenuates the
input signal. This ensures that the V
1.3V when the input voltage is at the desired compara-
tor trip point. Since the bias current of the comparator
is only a fraction of a nanoamp, the current in the volt-
age divider can be less than one microamp without los-
ing accuracy due to bias currents. The ICL7665A has a
2% threshold accuracy at +25°C, and a typical temper-
ature coefficient of 100ppm/°C including comparator
offset drift, eliminating the need for external poten-
tiometers in most applications.
Figure 4 adds another resistor to each voltage detector.
This third resistor supplies current from the HYST out-
put whenever the V
old. As the formulas show, this hysteresis resistor
affects only the lower trip point. Hysteresis (defined as
Figure 3. Simple Threshold Detector
R21
R11
V
IN1
_______________________________________________________________________________________
OUT1
OUT2
SET
OUT1
SET1
V
V
IN1
IN2
Basic Over/Undervoltage
ICL7665
input is above the 1.3V thresh-
V+
Microprocessor Voltage Monitor with
SET
V
TRIP1
OUT2
SET2
input is 1.3V. The exter-
Detection Circuits
Dual Over/Undervoltage Detection
V
TRIP2
SET
V
IN2
R22
R12
terminal is at
the difference between the upper and lower trip points)
keeps noise or small variations in the input signal from
repeatedly switching the output when the input signal
remains near the trip point for a long period of time.
The third basic circuit, Figure 5, is suitable only when the
voltage to be detected is also the power-supply voltage for
the ICL7665. This circuit has the advantage that all of the
current flowing through the input divider resistors flows
through the hysteresis resistor. This allows the use of
higher-value resistors, without hysteresis output leakage
having an appreciable effect on the trip point.
Figure 4. Threshold Detector with Hysteresis
1) Choose a value for R11. This value determines the
2) Calculate R21 based on R11 and the desired trip
R21 = R11
R21
R11
amount of current flowing though the input divider,
equal to V
range of 10k to 10M .
point:
V
IN1
V+
0V
(
R31
SET
OUT1
OUT2
———————
V
V
V
IN1
IN2
TRIP
/ R11. R11 can typically be in the
V
OUT1
SET1
HYST1
V
SET
L1
– V
ICL7665
Resistor-Value Calculations
SET
V+
V
U1
HYST2
OUT2
SET2
V
)
L2
= R11
V
U2
R32
0V
V+
(
——————
V
TRIP
1.3V
V
IN2
Figure 3
– 1.3V
R12
R22
)
7