MAX6703TKA+TG071 Maxim Integrated, MAX6703TKA+TG071 Datasheet - Page 9
MAX6703TKA+TG071
Manufacturer Part Number
MAX6703TKA+TG071
Description
Supervisory Circuits Triple uPower Supervisor
Manufacturer
Maxim Integrated
Series
MAX6701, MAX6701A, MAX6702, MAX6702A, MAX6703, MAX6703A, MAX6704, MAX6705, MAX6705A, MAX6706, MAX6706A, MAX6707, MAX6707A, MAX6708r
Datasheet
1.MAX6703TKATG071.pdf
(12 pages)
Specifications of MAX6703TKA+TG071
Rohs
yes
Number Of Voltages Monitored
3
Monitored Voltage
2.5 V, 3 V, 3.3 V, 5 V
Undervoltage Threshold
4.5 V, Adjustable
Overvoltage Threshold
4.75 V, Adjustable
Output Type
Active Low, Open Drain
Manual Reset
Resettable
Watchdog
Watchdog
Battery Backup Switching
No Backup
Supply Voltage - Max
5.5 V
Maximum Operating Temperature
+ 125 C
Mounting Style
SMD/SMT
Chip Enable Signals
No
Maximum Power Dissipation
714 mW
Minimum Operating Temperature
- 40 C
Power Fail Detection
No
Supply Current (typ)
12 uA
Supply Voltage - Min
1.2 V
The MAX6701(A)/MAX6702(A)/MAX6703(A) include two
adjustable reset inputs for monitoring up to a total of
three system voltages (including V
for the monitored RST_IN supplies are externally set
with resistor-divider networks (Figure 8). The reset out-
put is asserted if any of the monitored supplies (V
RST_IN1, or RST_IN2) go below its specified threshold
and remains asserted for the reset timeout period after
all supplies are above their thresholds.
When V
RESET output no longer sinks current—it becomes an
open circuit. High-impedance CMOS logic inputs can
drift to undetermined voltages if left undriven. If a pull-
down resistor is added to the RESET pin as shown in
Figure 9, any stray charge or leakage currents are
drained to ground, holding RESET low. A resistor value
(R1) is not critical; 100kΩ is large enough not to load
RESET and small enough to pull RESET to ground. This
application works for push-pull output only (not for
open-drain resets).
Figure 7. MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A) Watchdog Timing
Low-Voltage, SOT23 µP Supervisors with Power-
(RESET)
( ) ARE FOR MAX6702(A)/MAX6706(A) ONLY.
Fail In/Out, Manual Reset, and Watchdog Timer
RESET
WDO
WDI
MR
+5V
t
+5V
+5V
+5V
+5V
CC
WDI
0V
0V
0V
0V
0V
falls below 1V, the MAX6701–MAX6708
Applications Information
_______________________________________________________________________________________
t
WD
Output Down to V
Ensuring a Valid
t
WD
CC
). The thresholds
Reset Input
t
RP
t
WD
RESET
CC
= 0
CC
,
Other systems can be monitored by connecting a volt-
age-divider to PFI and adjusting the ratio appropriately.
In noisy systems, a capacitor between PFI and GND
reduces the power-fail circuit’s sensitivity to high-fre-
quency noise on the line being monitored. Reset can
be asserted on other voltages in addition to the V
supply line. Connect PFO to MR to initiate a reset out-
put pulse when PFI drops below 0.62V. Figure 10
shows the MAX6704–MAX6708 configured to assert a
reset output when the secondary supply falls below the
reset threshold.
Connect WDO to MR to force a watchdog timeout to gen-
erate a reset pulse for only the reset timeout period on the
MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A). When the MAX6704 watch-
dog times out, reset outputs are automatically asserted
(no external connections required). For the MAX6701/
MAX6702/MAX6703/MAX6705/MAX6706/MAX6707 non-A
versions, do not connect WDO to MR; this creates a
locked condition.
Figure 8. Calculating Adjustable Voltage Thresholds
V
EXTERNAL
V
WHERE V
EXT-TH
Monitoring Other System Voltages
=
R1
R2
(
EXT-TH
1 + R1
R2
IS THE EXTERNAL VOLTAGE TRIP LEVEL.
)
x 0.62V
from Watchdog Overflow
PFI, RST_IN1, OR RST_IN2
0.62V
MAX6701(A)–
MAX6708
Generating a Reset
R1 = R2 x
(
V
0.62
EXT-TH
- 1
)
CC
9