M41T11 Serial real-time clock (RTC) with 56 bytes of NVRAM Datasheet − production data Features ■ Counters for seconds, minutes, hours, day, date, month, years and century ■ 32 KHz crystal oscillator integrating load capacitance (12.5 pF) providing exceptional oscillator stability and high crystal series resistance operation ■ Serial interface supports I2C bus (100 kHz protocol) ■ Ultra-low battery supply current of 0.8 µA (typ. at 3 V) ■ 2.0 to 5.
Contents M41T11 Contents 1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1 3 2-wire bus characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1.1 Bus not busy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1.
M41T11 List of tables List of tables Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11. Table 12. Table 13. Table 14. Table 15. Table 16. Table 17. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Register map . . . . . . . . . . . . . . .
List of figures M41T11 List of figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Figure 20. 4/30 Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 8-pin SOIC connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
M41T11 1 Description Description The M41T11 is a low-power serial real-time clock (RTC) with 56 bytes of NVRAM. A built-in 32.768 kHz oscillator (external crystal controlled) and the first 8 bytes of the RAM are used for the clock/calendar function and are configured in binary-coded decimal (BCD) format. Addresses and data are transferred serially via a two-line bidirectional bus. The built-in address register is incremented automatically after each write or read data byte.
Description M41T11 Table 1. Signal names OSCI Oscillator input OCSO Oscillator output FT/OUT Figure 2. Frequency test/output driver (open drain) SDA Serial data address input/output SCL Serial clock VBAT Battery supply voltage VCC Supply voltage VSS Ground 8-pin SOIC connections M41T11 OSCI OSCO VBAT VSS 8 7 6 5 1 2 3 4 VCC FT/OUT SCL SDA AI01001 Figure 3.
M41T11 Description Figure 4. Block diagram 1 Hz OSCI OSCILLATOR 32.
Operation 2 M41T11 Operation The M41T11 clock operates as a slave device on the serial bus. Access is obtained by implementing a start condition followed by the correct slave address (D0h).
M41T11 2.1.3 Operation Stop data transfer A change in the state of the data line, from low to high, while the clock is high, defines the STOP condition. 2.1.4 Data valid The state of the data line represents valid data when after a start condition, the data line is stable for the duration of the high period of the clock signal. The data on the line may be changed during the low period of the clock signal. There is one clock pulse per bit of data.
Operation Figure 6. M41T11 Acknowledgement sequence CLOCK PULSE FOR ACKNOWLEDGEMENT START SCLK FROM MASTER 1 DATA OUTPUT BY TRANSMITTER 2 8 MSB 9 LSB DATA OUTPUT BY RECEIVER AI00601 Figure 7. Bus timing requirements sequence SDA tBUF tHD:STA tHD:STA tR tF SCL tHIGH P S tLOW tSU:DAT tHD:DAT tSU:STA SR tSU:STO P AI00589 1.
M41T11 Operation Table 2. AC characteristics Parameter(1) Symbol Min Max Unit 0 100 kHz fSCL SCL clock frequency tLOW Clock low period 4.7 µs tHIGH Clock high period 4 µs tR SDA and SCL rise time 1 µs tF SDA and SCL fall time 300 ns tHD:STA START condition hold time (after this period the first clock pulse is generated) tSU:STA tSU:DAT tHD:DAT (2) tSU:STO tBUF 4 µs START condition setup time (only relevant for a repeated start condition) 4.
Operation Figure 8. M41T11 Slave address location R/W SLAVE ADDRESS A 1 LSB MSB START 1 0 1 0 0 0 AI00602 R/W SLAVE ADDRESS DATA n+1 ACK DATA n ACK BUS ACTIVITY: S ACK WORD ADDRESS (An) ACK S R/W SDA LINE ACK BUS ACTIVITY: MASTER START Read mode sequence START Figure 9. STOP SLAVE ADDRESS DATA n+X P NO ACK AI00899 STOP R/W SLAVE ADDRESS 12/30 DATA n+X P NO ACK BUS ACTIVITY: DATA n+1 ACK DATA n ACK S ACK SDA LINE ACK BUS ACTIVITY: MASTER START Figure 10.
M41T11 2.3 Operation Write mode In this mode the master transmitter transmits to the M41T11 slave receiver. Bus protocol is shown in Figure 11. Following the START condition and slave address, a logic '0' (R/W = 0) is placed on the bus and indicates to the addressed device that word address An will follow and is to be written to the on-chip address pointer.
Clock operation 3 M41T11 Clock operation The eight byte clock register (see Table 3) is used to both set the clock and to read the date and time from the clock, in a binary coded decimal format. Seconds, minutes, and hours are contained within the first three registers. Bits D6 and D7 of clock register 2 (hours register) contain the CENTURY ENABLE bit (CEB) and the CENTURY bit (CB).
M41T11 Clock operation Table 3. Register map(1) Data Function/range Address D7 D6 D5 D4 D3 D2 D1 D0 BCD format 0 ST 10 seconds Seconds Seconds 00-59 1 X 10 minutes Minutes Minutes 00-59 2 CEB(2) CB 3 X X X 4 X X 10 date 5 X X X 6 7 10 hours X Hours X Day 10 M. 10 years OUT FT S Century/hours 0-1/00-23 Day 01-07 Date Date 01-31 Month Month 01-12 Years Year 00-99 Calibration Control 1.
Clock operation M41T11 adjustment per calibration step in the calibration register. Assuming that the oscillator is in fact running at exactly 32,768 Hz, each of the 31 increments in the calibration byte would represent +10.7 or –5.35 seconds per month which corresponds to a total range of +5.5 or –2.75 minutes per month. Two methods are available for ascertaining how much calibration a given M41T11 may require.
M41T11 Clock operation Figure 12. Crystal accuracy across temperature Frequency (ppm) 20 0 –20 –40 –60 –80 ΔF = K x (T –T )2 O F –100 K = –0.036 ppm/°C2 ± 0.006 ppm/°C2 –120 TO = 25°C ± 5°C –140 –160 –40 –30 –20 –10 0 10 20 30 40 50 60 70 80 Temperature °C AI00999b Figure 13.
Maximum ratings 4 M41T11 Maximum ratings Stressing the device above the rating listed in the absolute maximum ratings table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the operating sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 4.
M41T11 5 DC and AC parameters DC and AC parameters This section summarizes the operating and measurement conditions, as well as the DC and AC characteristics of the device. The parameters in the following DC and AC characteristic tables are derived from tests performed under the measurement conditions listed in Table 5: Operating and AC measurement conditions. Designers should check that the operating conditions in their projects match the measurement conditions when using the quoted parameters. Table 5.
DC and AC parameters Table 6. M41T11 Capacitance Parameter(1)(2) Symbol CIN COUT(3) tLP Min Max Unit Input capacitance (SCL) 7 pF Output capacitance (SDA, FT/OUT) 10 pF 1000 ns Low-pass filter input time constant (SDA and SCL) 250 1. Effective capacitance measured with power supply at 5 V; sampled only, not 100% tested. 2. At 25°C, f = 1 MHz. 3. Outputs deselected. Table 7.
M41T11 DC and AC parameters Figure 15. Power down/up mode AC waveforms VCC VSO tPD tREC SDA SCL DON'T CARE AI00596 Table 9. Power down/up AC characteristics Parameter(1)(2) Symbol Min Max Unit tPD SCL and SDA at VIH before power down 0 ns tREC SCL and SDA at VIH after power up 10 µs 1. Valid for ambient operating temperature: TA = –40 to 85°C; VCC = 2.0 to 5.5 V (except where noted). 2. VCC fall time should not exceed 5 mV/µs. Table 10.
Package mechanical data 6 M41T11 Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK® is an ST trademark.
M41T11 Package mechanical data Figure 16. SO8 – 8-lead plastic small outline package outline h x 45˚ A2 A c ccc b e 0.25 mm GAUGE PLANE D k 8 E1 E 1 A1 L L1 SO-A 1. Drawing is not to scale. Table 11. SO8 – 8-lead plastic small outline (150 mils body width) package mechanical data millimeters inches Symbol Typ Min A Max Typ Min 1.75 Max 0.069 A1 0.10 A2 1.25 b 0.28 0.48 0.011 0.019 c 0.17 0.23 0.007 0.009 ccc 0.25 0.004 0.010 0.049 0.10 0.004 D 4.90 4.80 5.
Package mechanical data M41T11 Figure 17. SOH28 – 28-lead plastic small outline, battery SNAPHAT® package outline A2 A C B eB e CP D N E H A1 α L 1 SOH-A 1. Drawing is not to scale. Table 12. SOH28 – 28-lead plastic small outline, battery SNAPHAT® package mechanical data mm inches Symb Typ Min A Typ Min 3.05 Max 0.120 A1 0.05 0.36 0.002 0.014 A2 2.34 2.69 0.092 0.106 B 0.36 0.51 0.014 0.020 C 0.15 0.32 0.006 0.012 D 17.71 18.49 0.697 0.728 E 8.23 8.89 0.
M41T11 Package mechanical data Figure 18. SH – 4-pin SNAPHAT® housing for 48 mAh battery & crystal package outline A1 A2 A3 A eA B L eB D E SHTK-A 1. Drawing is not to scale. Table 13. SH – 4-pin SNAPHAT® housing for 48 mAh battery & crystal, package mechanical data mm inches Symb Typ Min A Max Typ Min 9.78 Max 0.385 A1 6.73 7.24 0.265 0.285 A2 6.48 6.99 0.255 0.275 A3 0.38 0.015 B 0.46 0.56 0.018 0.022 D 21.21 21.84 0.835 0.860 E 14.22 14.99 0.560 0.
Package mechanical data M41T11 Figure 19. SH – 4-pin SNAPHAT® housing for 120 mAh battery & crystal, package outline A1 A2 A3 A eA B L eB D E SHTK-B 1. Drawing is not to scale. Table 14. SH – 4-pin SNAPHAT® housing for 120 mAh battery & crystal, package mech. data mm inches Symb Typ Min A Typ Min 10.54 Max 0.415 A1 8.00 8.51 0.315 0.335 A2 7.24 8.00 0.285 0.315 A3 26/30 Max 0.38 0.015 B 0.46 0.56 0.018 0.022 D 21.21 21.84 0.835 0.860 E 17.27 18.03 0.680 0.
M41T11 7 Part numbering Part numbering Table 15. Ordering information scheme Example: M41T 11 M 6 F Device type M41T Supply voltage 11 = VCC = 2.0 to 5.5 V(1) Package M = SO8 (150 mil width) MH(2) = SOH28 Temperature range 6 = –40 to 85°C Shipping method F = ECOPACK® package, tape & reel 1. SOH28 supply voltage is 3.3 V to 5.5 V. 2. The SOIC package (SOH28) requires the SNAPHAT® battery package which is ordered separately (see Table 16).
Environmental information 8 M41T11 Environmental information Figure 20. Recycling symbols This product contains a non-rechargeable lithium (lithium carbon monofluoride chemistry) button cell battery fully encapsulated in the final product. Recycle or dispose of batteries in accordance with the battery manufacturer's instructions and local/national disposal and recycling regulations.
M41T11 Revision history 9 Revision history Table 17. Revision history Date Revision 03-Oct-2007 7 Added lead-free second level interconnect information to cover page and Section 6: Package mechanical data; some text changes; updated Table 4. 02-May-2008 8 Updated Figure 16, Table 11, 15. 08-Jan-2009 9 Updated Table 4, Section 6: Package mechanical data; added Section 8: Environmental information.
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