Arizona Microtek, Inc.

AZT70

Programmable Capacitive Tuning IC

www.azmicrotek.com

+1-480-962-5881

6

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May 2012, Rev 1.2

Table 4 – Data writing sequence for EEPROM

Step

Action

1

Determine the desired capacitor control word with the operational power supply voltage and

desired oscillator conditions

2

3

If EEPROM is not already erased, erase EEPROM (see ERASING THE EEPROM)

4

Read the current state of the EEPROM bits (see READING BACK FROM THE EEPROM)

5

Compare the desired control word to the stored EEPROM control word. Count the number of

differences so as to prevent double/redundant writing

6

One bit at a time, load the first desired control word bit (bit selection for EEPROM is active LOW)

7

Set the PV pin to +6V (≥5.6V, ≤6.1V) with the pulse and idle shown in timing diagram (Figure 8)

8

Progress through all necessary control word bits by repeating steps 5 & 6 until all bits are set to the

desired control word.

9

Verify the correct EEPROM contents by reading back the individual bits

For an example of writing bits into the EEPROM, suppose the desired capacitance is 3.43pF. The control word becomes

‘00000010100’ (Figure 6). Also suppose the EEPROM bits have been erased and therefore logic high (The AZT70 is

initially shipped in this condition). Since bit0 is the first bit to be loaded, the bit sequence becomes 0-0-1-0-1-0-0-0-0-0-0.

However, as described before, selecting bits for the EEPROM are active LOW, which will invert the logical values in the

sequence to 1-1-0-1-0-1-1-1-1-1-1 (Figure 7). Note the differences between the EEPROM bits and the converted control

word. Since there are 2 differences, two write cycles are required as only 1 bit should be written at a time. Figure 8 shows

the timing for bit2 while Figure 9 shows the timing for bit4.

bit 0

bit 1

bit 2

bit 3

bit 4

bit 5

bit 6

bit 7

bit 8

bit 9

bit 10

Figure 6 – Desired control word

bit 0

bit 1

bit 2

bit 3

bit 4

bit 5

bit 6

bit 7

bit 8

bit 9

bit 10

bit 0

bit 1

bit 2

bit 3

bit 4

bit 5

bit 6

bit 7

bit 8

bit 9

bit 10

DA

EEPROM

difference

difference

Figure 7 – Converted control word and differences from known EEPROM states