MCP7940M
Low-Cost I
2
C™ Real-Time Clock/Calendar with SRAM
Device Selection Table
Part Number
MCP7940M
SRAM
(Bytes)
64
Description:
The MCP7940M series of low-power Real-Time Clocks
(RTC) uses digital timing compensation for an accurate
clock/calendar and a programmable output control for
versatility. Using a low-cost 32.768 kHz crystal, it tracks
time
using
several
internal
registers.
For
2
C™ bus.
communication, the MCP7940M uses the I
The clock/calendar automatically adjusts for months
with fewer than 31 days, including corrections for
leap years. The clock operates in either the 24-hour
or 12-hour format with an AM/PM indicator and
settable alarm(s) to the second, minute, hour, day of
the week, date or month. Using the programmable
CLKOUT, frequencies of 32.768, 8.192 and 4.096
kHz and 1 Hz can be generated from the external
crystal.
The RTC series of devices are available in the standard
8-lead SOIC, TSSOP, MSOP, PDIP and 2x3 TDFN
packages.
Features:
• Real-Time Clock/Calendar (RTCC):
- Hours, Minutes, Seconds, Day of Week, Day,
Month and Year
- Dual alarm with single output
• On-Chip Digital Trimming/Calibration:
- Range -127 to +127 ppm
- Resolution 1 ppm
• Programmable Open-Drain Output Control:
- CLKOUT with 4 selectable frequencies
- Alarm output
• 64 Bytes SRAM
• Low-Power CMOS Technology:
- Dynamic Current: 400
A
max write
• 100 kHz and 400 kHz Compatibility
• ESD Protection >4,000V
• Packages include 8-Lead SOIC, TSSOP, 2x3
TDFN, MSOP and PDIP
• Pb-Free and RoHS Compliant
• Temperature Ranges:
- Industrial (I): -40°C to +85°C
Package Types
MSOP
TDFN
X1
X2
NC
V
SS
1
2
3
4
8
7
6
5
SOIC, TSSOP
X1
X2
NC
V
SS
1
2
3
4
8
7
6
5
V
CC
MFP
SCL
SDA
V
CC
MFP
SCL
SDA
X1 1
X2 2
NC 3
V
SS
4
8 V
CC
7 MFP
6 SCL
5 SDA
PDIP
X1
X2
NC
V
SS
1
2
3
4
8
7
6
5
V
CC
MFP
SCL
SDA
2012 Microchip Technology Inc.
Preliminary
DS22292A-page 1
MCP7940M
1.0
ELECTRICAL CHARACTERISTICS
Absolute Maximum Ratings
(†)
V
CC
.............................................................................................................................................................................6.5V
All inputs and outputs w.r.t. V
SS
..........................................................................................................-0.6V to V
CC
+1.0V
Storage temperature ...............................................................................................................................-65°C to +150°C
Ambient temperature with power applied................................................................................................-40°C to +125°C
ESD protection on all pins
4 kV
† NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional operation of the device at those or any other conditions above those
indicated in the operational listings of this specification is not implied. Exposure to maximum rating conditions for
extended periods may affect device reliability.
TABLE 1-1:
DC CHARACTERISTICS
Electrical Characteristics:
Industrial (I):
V
CC
= +1.8V to 5.5V
Min.
—
0.7 V
CC
—
0.05
V
CC
—
—
—
—
—
—
—
25
—
3
—
Typ.
Max.
—
—
0.3 V
CC
0.2 V
CC
—
Units
—
V
V
V
—
—
V
CC
= 2.5V to 5.5V
(Note
1)
T
A
= -40°C to +85°C
Conditions
DC CHARACTERISTICS
Param.
No.
D1
D2
D3
Sym.
—
V
IH
V
IL
V
HYS
Characteristic
SCL, SDA pins
High-level input voltage
Low-level input voltage
Hysteresis of Schmitt
Trigger inputs
(SDA, SCL pins)
Low-level output voltage
(MFP, SDA)
Input leakage current
Output leakage current
Pin capacitance
(SDA, SCL and MFP)
D4
D5
D6
D7
D8
D9
D10
D11
Note 1:
2:
V
OL
I
LI
I
LO
C
IN
,
C
OUT
0.40
±1
±1
10
300
400
1
V
A
A
pF
A
A
A
A
pF
I
OL
= 3.0 ma @ V
CC
= 4.5V
I
OL
= 2.1 ma @ V
CC
= 2.5V
V
IN
= V
SS
or V
CC
V
OUT
= V
SS
or V
CC
V
CC
= 5.0V
(Note
1)
T
A
= 25°C, f = 400 kHz
V
CC
= 5.5V, SCL = 400 kHz
V
CC
= 5.5V, SCL = 400 kHz
V
CC
= 5.5V, SCL = SDA = V
CC
V
CC
= 5.5V @ 25°C
(Note
2)
(Note
1)
I
CC
Read Operating current
I
CC
Write SRAM
I
CCS
IVcc
COSC
Standby current
Operating Current
Oscillator Pin
Capacitance
This parameter is periodically sampled and not 100% tested.
Oscillator Running.
2012 Microchip Technology Inc.
Preliminary
DS22292A-page 3
MCP7940M
TABLE 1-2:
AC CHARACTERISTICS
Electrical Characteristics:
Industrial (I):
V
CC
= +1.8V to 5.5V
Characteristic
Clock frequency
Clock high time
Clock low time
SDA and SCL rise time
(Note
1)
SDA and SCL fall time
(Note
1)
Min.
—
—
4000
600
4700
1300
—
—
—
—
4000
600
4700
600
0
250
100
4000
600
—
—
4700
1300
—
Max.
100
400
—
—
—
—
1000
300
1000
300
—
—
—
—
—
—
—
—
—
3500
900
—
—
50
Units
kHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
1.8V
V
CC
< 2.5V
2.5V
V
CC
5.5V
1.8V
V
CC
< 2.5V
2.5V
V
CC
5.5V
1.8V
V
CC
< 2.5V
2.5V
V
CC
5.5V
1.8V
V
CC
< 2.5V
2.5V
V
CC
5.5V
(Note
1
and
Note 2)
T
A
= -40°C to +85°C
Conditions
1.8V
V
CC
< 2.5V
2.5V
V
CC
5.5V
1.8V
V
CC
< 2.5V
2.5V
V
CC
5.5V
1.8V
V
CC
< 2.5V
2.5V
V
CC
5.5V
1.8V
V
CC
< 2.5V
2.5V
V
CC
5.5V
1.8V
V
CC
< 2.5V
2.5V
V
CC
5.5V
1.8V
V
CC
< 2.5V
2.5V
V
CC
5.5V
1.8V
V
CC
< 2.5V
2.5V
V
CC
5.5V
AC CHARACTERISTICS
Param.
Symbol
No.
1
2
3
4
5
6
7
8
9
10
11
12
F
CLK
T
HIGH
T
LOW
T
R
T
F
T
HD
:
STA
Start condition hold time
T
SU
:
STA
Start condition setup time
T
HD
:
DAT
Data input hold time
T
SU
:
DAT
T
SU
:
STO
T
AA
T
BUF
Data input setup time
Stop condition setup time
Output valid from clock
Bus free time: Time the bus
must be free before a new
transmission can start
Input filter spike suppression
(SDA and SCL pins)
13
T
SP
ns
Note 1:
Not 100% tested.
2:
The combined T
SP
and V
HYS
specifications are due to new Schmitt Trigger inputs, which provide improved
noise spike suppression. This eliminates the need for a T
I
specification for standard operation.
DS22292A-page 4
Preliminary
2012 Microchip Technology Inc.
Analog electronics
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