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PDF MCP7940N Data sheet ( Hoja de datos )
| Número de pieza | MCP7940N | |
| Descripción | Real-Time Clock/Calendar | |
| Fabricantes | Microchip | |
| Logotipo |  |
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MCP7940N
Battery-Backed I2C™ Real-Time Clock/Calendar with SRAM
Timekeeping Features:
• Real-Time Clock/Calendar (RTCC):
- Hours, Minutes, Seconds, Day of Week, Day,
Month, Year
- Leap year compensated to 2399
- 12/24 hour modes
• Oscillator for 32.768 kHz Crystals:
- Optimized for 6-9 pF crystals
• On-Chip Digital Trimming/Calibration:
- ±1 PPM resolution
- ±129 PPM range
• Dual Programmable Alarms
• Versatile Output Pin:
- Clock output with selectable frequency
- Alarm output
- General purpose output
• Power-Fail Time-Stamp:
- Time logged on switchover to and from
Battery mode
Low-Power Features:
• Wide Voltage Range:
- Operating voltage range of 1.8V to 5.5V
- Backup voltage range of 1.3V to 5.5V
• Low Typical Timekeeping Current:
- Operating from VCC: 1.2 µA at 3.3V
- Operating from battery backup: 925 nA at
3.0V
• Automatic Switchover to Battery Backup
User Memory:
• 64-byte Battery-Backed SRAM
Operating Ranges:
• 2-Wire Serial Interface, I2C™ Compatible
- I2C clock rate up to 400 kHz
• Temperature Range:
- Industrial (I): -40°C to +85°C
- Extended (E): -40°C to +125°C
Packages:
• 8-Lead SOIC, MSOP, TSSOP, PDIP and 2x3
TDFN
General Description:
The MCP7940N Real-Time Clock/Calendar (RTCC)
tracks time using internal counters for hours, minutes,
seconds, days, months, years, and day of week.
Alarms can be configured on all counters up to and
including months. For usage and configuration, the
MCP7940N supports I2C communications up to 400
kHz.
The open-drain, multi-functional output can be
configured to assert on an alarm match, to output a
selectable frequency square wave, or as a general
purpose output.
The MCP7940N is designed to operate using a 32.768
kHz tuning fork crystal with external crystal load
capacitors. On-chip digital trimming can be used to
adjust for frequency variance caused by crystal
tolerance and temperature.
SRAM and timekeeping circuitry are powered from the
back-up supply when main power is lost, allowing the
device to maintain accurate time and the SRAM
contents. The times when the device switches over to
the back-up supply and when primary power returns
are both logged by the power-fail time-stamp.
Package Types
SOIC, MSOP, TSSOP(1), PDIP(1)
X1
X2
VBAT
VSS
1
2
3
4
8 VCC
7 MFP
6 SCL
5 SDA
TDFN(1)
X1
X2
VBAT
VSS
1
2
3
4
8 VCC
7 MFP
6 SCL
5 SDA
Note 1: Available in I-temp only.
2010-2014 Microchip Technology Inc.
DS20005010F-page 1
1 page  
MCP7940N
TABLE 1-2: AC CHARACTERISTICS
AC CHARACTERISTICS
Electrical Characteristics:
Industrial (I):
VCC = +1.8V to 5.5V
Extended (E): VCC = +1.8V to 5.5V
TA = -40°C to +85°C
TA = -40°C to +125°C
Param.
No.
Symbol
Characteristic
Min.
Typ. Max. Units
Conditions
1
FCLK
Clock frequency
— — 100 kHz 1.8V VCC < 2.5V
— — 400
2.5V VCC 5.5V
2 THIGH Clock high time
4000
600
— — ns 1.8V VCC < 2.5V
——
2.5V VCC 5.5V
3 TLOW Clock low time
4700
1300
— — ns 1.8V VCC < 2.5V
——
2.5V VCC 5.5V
4 TR SDA and SCL rise time
(Note 1)
— — 1000 ns 1.8V VCC < 2.5V
— — 300
2.5V VCC 5.5V
5 TF SDA and SCL fall time
(Note 1)
— — 1000 ns 1.8V VCC < 2.5V
— — 300
2.5V VCC 5.5V
6 THD:STA Start condition hold time
4000
600
— — ns 1.8V VCC < 2.5V
——
2.5V VCC 5.5V
7 TSU:STA Start condition setup time
4700
600
— — ns 1.8V VCC < 2.5V
——
2.5V VCC 5.5V
8 THD:DAT Data input hold time
0 — — ns (Note 2)
9 TSU:DAT Data input setup time
250 — — ns 1.8V VCC < 2.5V
100 — —
2.5V VCC 5.5V
10 TSU:STO Stop condition setup time
4000
600
— — ns 1.8V VCC < 2.5V
——
2.5V VCC 5.5V
11 TAA Output valid from clock
— — 3500 ns 1.8V VCC < 2.5V
— — 900
2.5V VCC 5.5V
12 TBUF Bus free time: Time the bus 4700
must be free before a new
1300
transmission can start
— — ns 1.8V VCC < 2.5V
——
2.5V VCC 5.5V
13 TSP
Input filter spike suppression
(SDA and SCL pins)
—
— 50 ns (Note 1)
14 TFVCC VCC fall time
300 — — s (Note 1)
15 TRVCC VCC rise time
0 — — s (Note 1)
16 FOSC Oscillator frequency
—
32.768 —
kHz —
17
TOSF
Oscillator timeout period
1 — — ms (Note 1)
Note 1: Not 100% tested.
2: As a transmitter, the device must provide an internal minimum delay time to bridge the undefined region
(minimum 300 ns) of the falling edge of SCL to avoid unintended generation of Start or Stop conditions.
2010-2014 Microchip Technology Inc.
DS20005010F-page 5
5 Page 
MCP7940N
5.0 FUNCTIONAL DESCRIPTION
The MCP7940N is a highly-integrated Real-Time
Clock/Calendar (RTCC). Using an on-board, low-
power oscillator, the current time is maintained in sec-
onds, minutes, hours, day of week, date, month, and
year. The MCP7940N also features 64 bytes of general
purpose SRAM. Two alarm modules allow interrupts to
be generated at specific times with flexible comparison
options. Digital trimming can be used to compensate
for inaccuracies inherent with crystals. Using the
backup supply input and an integrated power switch,
the MCP7940N will automatically switch to backup
power when primary power is unavailable, allowing the
current time and the SRAM contents to be maintained.
The time-stamp module captures the time when pri-
mary power is lost and when it is restored.
The RTCC configuration and Status registers are used
to access all of the modules featured on the
MCP7940N.
5.1 Memory Organization
The MCP7940N features two different blocks of mem-
ory: the RTCC registers and general purpose SRAM
(Figure 5-1). They share the same address space,
accessed through the ‘1101111X’ control byte.
Unused locations are not accessible. The MCP7940N
will not acknowledge if the address is out of range, as
shown in the shaded region of the memory map in
Figure 5-1.
The RTCC registers are contained in addresses 0x00-
0x1F. Table 5-1 shows the detailed RTCC register map.
There are 64 bytes of user-accessible SRAM, located
in the address range 0x20-0x5F. The SRAM is a sepa-
rate block from the RTCC registers. All RTCC registers
and SRAM locations are maintained while operating
from backup power.
FIGURE 5-1:
MEMORY MAP
0x00
0x06
0x07
0x09
0x0A
0x10
0x11
0x17
0x18
0x1F
0x20
RTCC Registers/SRAM
Time and Date
Configuration and Trimming
Alarm 0
Alarm 1
Power-Fail/Power-Up Time-Stamps
SRAM (64 Bytes)
0x5F
0x60
Unimplemented; device does not ACK
0xFF
I2C™ Address: 1101111x
2010-2014 Microchip Technology Inc.
DS20005010F-page 11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet MCP7940N.PDF ] | |
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