Pin description – Rainbow Electronics MAX16040 User Manual
Page 7
MAX16033–MAX16040
Low-Power Battery Backup
Circuits in Small µDFN Packages
_______________________________________________________________________________________
7
Pin Description
PIN
MAX16033–
MAX16036
(10-pin µDFN)
MAX16037–
MAX16040
(8-pin µDFN)
NAME
FUNCTION
1
1
RESET
Active-Low Reset Output. RESET remains low when V
CC
is below the reset
threshold (V
TH
), the manual-reset input is low, or RESETIN is low. It asserts low in
pulses when the internal watchdog times out. RESET remains low for the reset
timeout period (t
RP
) after V
CC
rises above the reset threshold, after the manual-reset
input goes from low to high, after RESETIN goes high, or after the watchdog triggers
a reset event. The MAX160_ _L is an active-low push-pull output, while the
MAX160_ _P is an active-low open-drain output.
2
—
CEIN
Chip-Enable Input. The input to the chip-enable gating circuit. Connect to GND or
OUT if not used.
3
2
PFI
Power-Fail Input. PFO goes low when V
PFI
falls below 1.235V.
4
3
GND
Ground
MR
Manual-Reset Input (MAX16033/MAX16037). Driving MR low asserts RESET. RESET
remains asserted as long as MR is low and for the reset timeout period (t
RP
) after
MR transitions from low to high. Leave unconnected, or connect to V
CC
if not used.
MR has an internal 20k
Ω pullup to V
CC
.
WDI
Watchdog Input (MAX16034/MAX16038). If WDI remains high or low for longer than
the watchdog timeout period (t
WD
), the internal watchdog timer runs out and a reset
pulse is triggered for the reset timeout period (t
RP
). The internal watchdog clears
whenever RESET asserts or whenever WDI sees a rising or falling edge (Figure 2).
BATTON
Battery-On Output (MAX16035/MAX16039). BATTON goes high during battery
backup mode.
5
4
RESETIN
Reset Input (MAX16036/MAX16040). When RESETIN falls below 1.235V, RESET
asserts. RESET remains asserted as long as RESETIN is low and for at least t
RP
after RESETIN goes high.
6
5
PFO
Active-Low Power-Fail Output. PFO goes low when V
PFI
falls below 1.235V. PFO
stays low until V
PFI
goes above 1.235V. PFO also goes low when V
CC
falls below
the reset threshold voltage.
7
6
V
CC
Supply Voltage, 1.2V to 5.5V
8
7
OUT
Output. OUT sources from V
CC
when RESET is not asserted and from the greater of
V
CC
or BATT when V
CC
is below the reset threshold voltage.
9
8
BATT
Backup Battery Input. When V
CC
falls below the reset threshold, OUT switches to
BATT if V
BATT
is 40mV greater than V
CC
. When V
CC
rises above V
BATT
, OUT
switches to V
CC
. The 40mV hysteresis prevents repeated switching if V
CC
falls
slowly.
10
—
CEOUT
Chip-Enable Output. CEOUT goes low only when CEIN is low and reset is not
asserted. When CEOUT is disconnected from CEIN, CEOUT is actively pulled up to
OUT.