MAX8215EPD Maxim Integrated, MAX8215EPD Datasheet - Page 8

• 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

±5V, ±12V (±15V) Dedicated
Microprocessor Voltage Monitors
Figure 5. Microprocessor Reset Circuit with 200ms Time Delay
The supply voltage to these devices can also be moni-
tored by the 5V dedicated comparator and the auxiliary
comparator. Figure 4 shows a circuit that monitors the
voltage connected at V
undervoltage conditions. The +5V comparator checks
for undervoltage conditions while the auxiliary compara-
tor monitors overvoltage conditions. In general, no extra
supply bypassing circuitry (other than the normally rec-
ommended 0.1µF capacitor) is required when perform-
ing this function. However, using resistor values higher
than 100k
attention to eliminate potential oscillations. Also, partic-
ularly low pull-up resistor values on DOUT contribute to
the likelihood of the auxiliary comparator’s oscillation.
See the section Eliminating Output Oscillation.
It is often necessary to reset a microprocessor (µP) when
its supply voltage drops below a certain level. Figure 5’s
circuit generates a low output when the monitored volt-
age drops below the 5V monitor’s threshold. Additionally,
this output remains low for 200ms after the supply voltage
goes above the threshold. µP reset circuits typically
include this feature because it gives the µP time to be
fully reset after power has been restored, and allows any
capacitors in associated circuitry time to charge. Figure
6 shows this circuit’s waveforms and formulas.
8
____________Circuit with Time Delay
_______________________________________________________________________________________
+V
S
1 F
3
7
2
DIN
GND
+5V
at the auxiliary comparator’s input requires
Monitoring the Supply Voltage
MAX8215
MAX8216
0.1 F
PGND
8
Microprocessor Reset
DD
DOUT
OUT1
V
DD
for both overvoltage and
13
9
14
+5V
680k
680k
RESET
Figure 7 shows Figure 5’s µP reset circuit, but with the
monitored supply also powering the MAX8215. Figure
6’s waveforms and equations also apply to this circuit.
The MAX8215/MAX8216 comparator outputs correctly
display a low level down to a 0.8V typical supply voltage.
When the uncommitted comparator within the
MAX8215/MAX8216 is not used, tie the unused input to
either the positive supply or ground. This prevents noise
generation due to the comparator output switching from
one logic state to another (due to noise at the input).
Pull-up resistors are required at the outputs of each
comparator. Resistor values should not be less than
2.7k
save power by using higher values, e.g., 100k . Use
of higher-value resistors also minimizes the possibility
of oscillations due to a spurious feedback (see the sec-
tion Eliminating Output Oscillation).
If the voltages at the various inputs are kept within the
absolute maximum ratings, the device is not damaged.
However, high input voltages within this range can
cause the reference voltage to move. To prevent the
reference voltage from changing, limit the +5V input to
+17V; the -5V and -15V inputs to +1V; and the +15V
input to +60V. Negative input voltages within the
Figure 6. Microprocessor Reset with Time Delay Waveforms
INPUT VOLTAGE
NOTE: V
V
V
TRIP1
TRIP2
VOLTAGE
VOLTAGE
OUTPUT
OUTPUT
(DOUT)
(OUT1)
(V
IS FOR V
IS FOR V
S
if the outputs are pulled up to V
)
IN THIS CASE, IT IS EQUAL TO THE INTERNAL REFERENCE VOLTAGE.
TH
V
V
IS THE VOLTAGE AT THE INVERTING PIN OF THE TWO COMPARATORS.
TRIP2
TRIP1
GND
GND
GND
V
V
S
S
DD
DD
DECREASING;
INCREASING.
Output Pull-Up Resistors
Input Voltage Limitation
t
DLY =
-RC In 1 -
(
V
V
REF
Unused Inputs
CC
t
)
DLY
DD
. In general,