MAX8215EPD Maxim Integrated, MAX8215EPD Datasheet - Page 7

• Manufacturer Part Number: MAX8215EPD
• Description: Supervisory Circuits
• Manufacturer: Maxim Integrated
• Series: MAX8215, MAX8216r

Specifications of MAX8215EPD

• Number Of Voltages Monitored: 5
• Monitored Voltage: - 12 V, - 5 V, 5 V, 12 V
• Undervoltage Threshold: 4.521 V, 10.431 V, - 10.431 V, - 4.348 V
• Overvoltage Threshold: 4 V, 10.749 V, - 10.749 V, - 4.482 V
• Output Type: Open Drain
• Manual Reset: Not Resettable
• Watchdog: No Watchdog
• Battery Backup Switching: No Backup
• Supply Voltage - Max: 11 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• Package / Case: PDIP N
• Chip Enable Signals: No
• Maximum Power Dissipation: 800 mW
• Minimum Operating Temperature: - 40 C
• Power Fail Detection: No
• Supply Current (typ): 250 uA
• Supply Voltage - Min: 2.7 V

Figure 2. Undervoltage/Overvoltage Comparator Using the
Auxiliary Comparator
Adding hysteresis to a comparator creates two trip
points–one for the input voltage rising and one for the
input voltage falling. When the voltage at the
MAX8215/MAX8216 auxiliary comparator’s (noninvert-
ing) input falls, the threshold at which the comparator
switches equals the reference voltage connected to the
comparator’s inverting input. However, when the volt-
age at the noninverting input rises, the threshold
equals the reference voltage plus the amount of hys-
teresis voltage built into the part. The trip point is
somewhat more accurate when the hysteresis voltage
is not part of the threshold voltage (i.e., when the input
voltage is falling) because the tolerance of the hystere-
sis specification adds to the tolerance of the trip point.
Figure 2 shows connection of the auxiliary comparator
as either an undervoltage or overvoltage comparator.
Hysteresis makes this circuit more accurate when the
input voltage is dropping as opposed to rising. Figure
3 illustrates the comparator’s operation. The input volt-
age’s direction determines at which of two trip points
the comparator switches. Thus, the diagram includes
arrows that indicate whether the input voltage is rising
or falling. The formulas are provided for determining
trip-point voltages for specified resistors and for ease
in calculating appropriate resistor ratios for particular
trip points.
+V S
V
TRIP
=
(
R A
R
A
R B
+ R
R
B
B
)
7
(
Overvoltage and Undervoltage
V
REF
_______________________________________________________________________________________
DIN
)
1.24V REFERENCE
MAX8215
MAX8216
Detection Circuits
Microprocessor Voltage Monitors
DOUT
9
V DD
±5V, ±12V (±15V) Dedicated
180k
The MAX8215/MAX8216 comparator outputs correctly
display a low level down to 0.8V supply voltage. This is
useful in undervoltage applications where the monitored
power supply is also the supply connected to the V
pin. See the section Monitoring the Supply Voltage.
Figure 3. Undervoltage/Overvoltage Detector Waveforms and
Formulas
Figure 4. Monitoring Supply Powering the MAX8215/MAX8216
with Undervoltage and Overvoltage Comparators
INPUT VOLTAGE
TO DETERMINE THE TRIP VOLTAGES
FROM PARTICULAR RESISTOR
VALUES:
+V
VOLTAGE
OUTPUT
S
V
V
V
TRIP1 =
R1
TRIP2 =
HYST
R2
(V
S
)
= 16mV TYP
V
(V
V
V
REF
REF
TRIP2
TRIP1
GND
GND
V
+5V COMPARATOR IS ACTUATED WHEN V
COMPARATOR'S SPECIFIED TRIP LEVEL. THE AUXILIARY
COMPARATOR OUTPUT IS TRIPPED WHEN V
DD
(
+ V
1 +
HYST
3
7
2
RA
RB
DIN
GND
+5V
)
) 1 +
(
RA
RB
MAX8215
MAX8216
)
0.1 F
PGND
8
TO CALCULATE THE REQUIRED
RESISTOR RATIOS FOR PARTICULAR
TRIP VOLTAGES:
DOUT
OUT1
V
RA
RB
RA
RB
DD
=
=
V
UNDERVOLTAGE
V
V REF + V
13
9
14
TRIP1
REF
S
FALLS TO THE
V
S
TRIP2
OVERVOLTAGE
>
- 1
(
HYST
R1 + R2
V
R2
HYST
- 1
)
(
1 +
VREF
RA
RB
DD
)
7