em3027 EM Microelectronic, em3027 Datasheet - Page 22

• Manufacturer Part Number: em3027
• Description: Real-time Clock With I2c Or Spi Interface, Crystal Temperature Compensation, Battery Switchover And Trickle Charger
• Manufacturer: EM Microelectronic

Verified by design. Not tested in production
Notes:
Calculation of external-pull up
All of the following conditions have to be met:
Copyright © 2008, EM Microelectronic-Marin SA
07/08 – rev B
1) Falling time on SDA driven by EM3027 can be shorter than 20 + 0.1* C
2) There are parasitic diodes between SCL, SDA pads and
3) Device does not internally provide a hold time of 300ns as required by I2C standard.
- Rise time is equal to 0.847* R
- Maximum sink current driven by SDA pad in output mode => R
PU
* C
B
=> Rpu < t
.
Figure 8 : Timing - I2C
R max
/(0.847* C
Vcc
power supply.
B
PU
22
).
<
Vcc
/ I
B
SINK min
as required by I2C standard.
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