AS1506
Datasheet - Detailed Description
EEPROM (Non-Volatile Register)
There is an internal EEPROM register implemented to retain the wiper position after power down. During an ongoing
write cycle of the non-volatile register (tBUSY time) the system must not be powered down.
Data retention defines the ability of an EEPROM to retain data over time. The qualification has been done according to
JEDEC Retention Lifetime Specification (A117). The EEPROM is cycled to the specified endurance limit before the
data retention test is done. Based on activation energy of 0.6eV the data retention time derates over temperature as
shown in Figure 19 on page 8.
For the non-volatile register 1M endurance cycles and a data retention of 150 years are typical at 85 ºC. The non-vola-
tile register is factory trimmed to mid-scale.
Power-Up
The AS1506 contains an integrated power-up circuit. At power up, the data are transferred from the non-volatile mem-
ory to the wiper register. The wiper register moves to the stored position. This data transfer takes 5µs after the supply
has reached the POR trigger level.
Programming the Device
Write commands (see Table 6) require 16 clock cycles (see Figure 22 on page 12) to clock in the command and data.
Copy and Read commands (see Table 6) can use 8 clock cycles to clock in the command (see Figure 21 on page 11)
or 16 clock cycles. At 16 clock cycle commands the 8 data bits (D7:D0) are insignificant.
Table 6. Command/Data Word Format
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
Command
C7 C6 C5 C4 C3 C2 C1 C0 D7 D6 D5 D4 D3 D2 D1 D0
Write Wiper Register
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
Write to Non-Volatile Register
Copy Wiper Register to Non-
Volatile Register
0
0
0
0
1
1
0
1
0
0
0
0
0
0
0
0
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Copy Non-Volatile Register
to Wiper Register
Read Non-Volatile Register
Read Wiper Register
0
0
0
1
1
1
0
0
1
1
0
0
0
0
0
0
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Commands
Write Wiper Register
This is a 16-bit command (see Figure 22 on page 12). The first byte represents the command word starting with the
MSB bit of the command, the second byte represents the data written to the wiper register (starting with the MSB).
Data 0000 0000 the wiper moves the closest position to LOW, with data 1111 1111 the wiper moves to the closest posi-
tion to HIGH.
Note: At power-up the wiper position stored in the non-volatile memory are automatically loaded into the wiper regis-
ter, the wiper moves to the related position.
Write to Non-Volatile Register
This is a 16-bit command (see Figure 22 on page 12). The first byte represents the command word starting with the
MSB bit of the command, the second byte represents the data written to the non-volatile memory. The wiper position is
not changed by this command, since the wiper register is not affected.
There is a write non-volatile register time defined in the timing specification, which is required for storing the data in the
non-volatile register. During this time the device must not be powered down, otherwise the data stored in the non-vola-
tile register is corrupted.
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