MAX16016_0812 Datasheet, PDF (10/21 Pages) Maxim Integrated Products – Low-Power μP Supervisory Circuits with Battery-Backup Circuit and Chip-Enable Gating

Low-Power µP Supervisory Circuits with
Battery-Backup Circuit and Chip-Enable Gating
Pin Description—MAX16020/MAX16021
PIN
MAX16020 MAX16021
1
1
2
2
3
3
NAME
BATT
MR
PFI
FUNCTION
Backup Battery Input. If V_CC falls below its reset threshold, and if V_BATT > V_CC, OUT
connects to BATT. If V_CC rises above 1.01 x V_BATT, OUT connects to V_CC. Bypass BATT to
GND with a 0.1µF capacitor.
Active-Low Manual Reset Input. RESET asserts when MR is pulled low. RESET remains low
for the duration of reset timeout period after MR transitions from low to high. Connect MR to
OUT or leave unconnected if not used. MR is internally connected to OUT through a 30kΩ
pullup resistor.
Power-Fail Comparator Input. Connect PFI to a resistive divider to set the desired PFI
threshold. The PFI input is referenced to an internal threshold V_PFT, V_PFT-HYS internal
hysteresis provides noise immunity. The power-fail comparator is powered from OUT.
Watchdog Timer Input. If WDI remains high or low for longer than the watchdog timeout
4
4
WDI
period (t_WD), the internal watchdog timer runs out and asserts WDO. The internal watchdog
clears when reset asserts or whenever WDI sees a rising or falling edge. To disable the
watchdog feature, leave WDI unconnected or three-state the driver connected to WDI.
Active-Low Low-Line Output. LL goes low when V_CC falls to 2.5% above the reset threshold
5
5
LL
(Table 2). LL provides an early warning of V_CC failure before reset asserts. Use this output
to generate a nonmaskable interrupt (NMI) to initiate an orderly shutdown routine when
V_CC is falling.
Open-Drain Battery-Test Output. Pulses low for 1.3s every 24 hours during the battery
6
—
BATT_TEST voltage test. If V_BATT < 2.6V, BATTOK deasserts low. See Figure 6 for providing additional
load during the battery test.
Active-High Reset Output. RESET asserts when V_CC falls below the reset threshold or when
—
6
RESET MR asserts and stays asserted for the reset timeout period after VCC rises above the reset
threshold and MR deasserts.
7
7
BATTOK ^{Battery-OK Output. BATTOK goes low when the battery voltage falls below the BATTOK}
threshold (BATTOK is low when in battery-backup mode).
8
8
BATTON Active-High Battery-On Output. BATTON goes high when in battery-backup mode.
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