MAX16020PTEV+T Maxim Integrated Products, MAX16020PTEV+T Datasheet - Page 17

• Manufacturer Part Number: MAX16020PTEV+T
• Description: IC UP SUPERVISOR LP 16-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Simple Reset/Power-On Resetr

Specifications of MAX16020PTEV+T

• Number Of Voltages Monitored: 1
• Output: Open Drain or Open Collector
• Reset: Active Low
• Reset Timeout: 145 ms Minimum
• Voltage - Threshold: 1.571V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The power-fail comparators have a typical input hys-
teresis of V
tions where a power-supply line is being monitored
through an external voltage-divider (see the Monitoring
an Additional Supply section). Figure 4 shows how to
add hysteresis to the power-fail comparator. Select the
ratio of R1 and R2 so that PFI sees V
to the desired trip point (V
teresis. R3 is typically an order of magnitude greater
than R1 or R2. R3 should be larger than 50kΩ to pre-
vent it from loading down PFO. Capacitor C1 adds
additional noise rejection.
Figure 4. Adding Hysteresis to the Power-Fail Comparator
R1
R2
Battery-Backup Circuit and Chip-Enable Gating
V
IN
*OPTIONAL
PFO
C1*
+5V
0
PFT-HYS
R3
TO µP
______________________________________________________________________________________
Low-Power µP Supervisory Circuits with
. This is sufficient for most applica-
WHERE V
PFI
PFO
Adding Hysteresis to PFI
MAX16016L
MAX16020L
MAX16021L
PFT
TRIP
V
IS THE POWER-FAIL THRESHOLD VOLTAGE
GND
L
+5V
V
CC
V
H
V
). Resistor R3 adds hys-
V
= (V
L
TRIP
= R1 x
PFT
V
+ V
V
TRIP
(—
0.1µF
0.1µF
PFT
H
V
PFT-HYS
R2
PFT
= V
+
PFT
when V
V
—)
) x
CC
x
(—)
(–
R3
- V
R1+R2
R1
R2
R2
PFT
+
IN
–
V
R1
R3
IN
+ V
+ 1
falls
PFT
)
BATTON goes high when in battery-backup mode. Use
BATTON to indicate battery-switchover status or to sup-
ply base drive to an external pass transistor for higher
current applications (Figure 5).
The MAX16016/MAX16020/MAX16021 provide a bat-
tery-backup function. If a backup power source is not
used, connect BATT to GND and OUT to V
Figure 5. BATTON Driving an External Pass Transistor
Operation Without a Backup Power Source
0.1µF
Battery-On Indicator (Push-Pull Version)
V
CC
BATT
MR
V
CC
MAX16020L
BATTON
GND
CEOUT
RESET
CEIN
OUT
ADDRESS
DECODE
1µF
CE
RESET
CC
A0–A15
CMOS RAM
µP
.
17