SLE4428 Datasheet, PDF (10/17 Pages) Siemens Semiconductor Group – ICs for Chip Cards

SLE 4418
SLE 4428
3.1 Write/Erase Operations
Write/Erase Data Byte without Protect Bit
Remark: Erase means “0” →“1”, write means “1” → “0”.
There are three kinds of write/erase operations which are automatically executed by the chip:
– Erase and subsequent write (duration 203 clock pulses, f ≤ 20 kHz) (Fig.5)
– Write only: This procedure is suitable if single bits of one byte shall be changed only from “1”
to “0”. (duration 103 clock pulses, f ≤ 20 kHz) (Fig.6)
– Erase only (= FF; duration 103 clock pulses, f ≤ 20 kHz) (Fig.6).
Write/Erase Data Byte with Protect Bit
The protect bit is erased at delivery, it can be written only once. Write procedure see above.
Write Protect Bit with Data Comparison
The data has to be entered a second time. The protect bit is only written if the old and the new data
are identical.
The execution of write/erase commands are terminated internally after a given number of clock
cycles. The end of the operation is indicated by the transition from “1” to “0” on I/O. Only RST
transition from “0” to “1” sets I/O to state “1”.
Figure 5
Programming: Erase and Write
Semiconductor Group
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