MAX6909EO33 Maxim Integrated, MAX6909EO33 Datasheet - Page 9

• Manufacturer Part Number: MAX6909EO33
• Description: Real Time Clock
• Manufacturer: Maxim Integrated
• Series: MAX6909, MAX6910r

Specifications of MAX6909EO33

• Function: Clock, Calendar, Watchdog Timekeeper, NV SRAM Control
• Rtc Bus Interface: Serial
• Time Format: HH
• Rtc Memory Size: 31 B
• Supply Voltage - Max: 3.6 V
• Supply Voltage - Min: 3 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Package / Case: QSOP-20

The MAX6909/MAX6910 contain eight 8-bit timekeeping
registers, two burst address registers, a trickle charge
register, a control register, a configuration register, an
alarm configuration register, and seven alarm threshold
registers, all controlled through a 2-wire serial interface.
Figure 1 is the MAX6909/MAX6910 block diagram.
The OUT pin supplies voltage for CMOS RAM or other
ICs requiring the use of backup battery power. When
V
V
V
an on-board trickle charger charges BATT from V
BATT can act as a backup supply from either a battery
or SuperCap™. When operating from BATT, the battery-
on output (BATT ON) is pulled low and can be used as
an indicator of operation in battery backup mode.
SuperCap is a trademark of Baknor Industries.
CC
BATT
RST
PIN
10
11
12
13
14
15
16
17
18
19
20
1
2
3
4
5
6
7
8
9
rises above the reset threshold (V
and V
, OUT is connected to V
BATT
BATT ON
CX FAIL
CE OUT
RESET
RESET
NAME
CE IN
BATT
GND
OUT
ALM
SDA
PFO
I
WDI
SCL
V
PZT
PFI
MR
, BATT is connected to OUT. If enabled,
X1
X2
CC
2
_______________________________________________________________________________________
C-Compatible Real-Time Clocks with µP
Detailed Description
Backup Battery Input. When V
Connect BATT to GND if no backup battery supply is used.
Supply Output for CMOS RAM or Other ICs Requiring Use of Backup Battery Power. Bypass to GND with
at least a 0.1µF capacitor.
Logic Output Open Drain. BATT ON is low when the MAX6909/MAX6910 are powered from BATT.
Chip-Enable Input. Input to the chip-enable switch used for external RAM. Connect to V
Power-Fail Comparator Input. For monitoring external power supplies.
Manual Reset Input. The active-low input has an internal pullup resistor. Internal debouncing circuitry
ensures noise immunity. Leave open if unused.
Watchdog Input
Ground
32.768kHz Crystal Pin; Oscillator Input
32.768kHz Crystal Pin; Oscillator Output
Crystal Fail Output. Open drain, active low.
Serial Data Line. Data input/output connection for the 2-wire serial interface.
Serial Clock Line. Clock input connection for the 2-wire serial interface.
Alarm Output. Open drain, active low.
Piezo Transducer Output. Push-pull Piezo transducer output.
Power-Fail Comparator Output. Push-pull active low.
Chip-Enable Output. For controlling external RAM.
Open-Drain, Active-Low Reset Output
Push-Pull, Active-High Reset Output. Complement of RESET.
Main Supply Input. Bypass to GND with at least a 0.01µF capacitor.
CC
. When V
Supervisor and NV RAM Controller
RST
CC
) or above
falls below
CC
CC
falls below the reset threshold and V
.
There are two reset outputs, RESET and RESET. They
become active while V
(V
t
threshold, or a WDI pulse is not received when the
watchdog function is enabled. Reset thresholds are
available for 3V and 3.3V applications. See the Ordering
Information for specifics. MR is internally pulled high and
contains debounce circuitry to accommodate a manual
pushbutton reset switch. The WDI, when enabled, keeps
RESET and RESET from becoming active if it is strobed
once every t
table in the configuration register.
Other features include internal chip-enable gating
logic, which accepts a valid CE IN from a microproces-
sor and only gates it through as valid to CE OUT when
the MAX6909/MAX6910 are not in a reset state. This
can be used for disabling CMOS RAM to limit current
consumption when OUT is switched to BATT.
RP
RST
FUNCTION
after MR goes high, V
) or while manual reset (MR) is held low, and for
WDS
or t
WD
CC
. The watchdog timeout is selec-
BATT
is below the reset threshold
, OUT connects to BATT.
CC
Pin Description
rises above the reset
CC
if unused.
9