ISL78419ARZ-T Datasheet, PDF (16/20 Pages) Intersil Corporation – Integrated Automotive TFT-LCD Power Supply Regulator

ISL78419
Read Operation
A read operation consists of a three byte instruction followed by
one or more Data Bytes (see Figure 18). The master initiates the
operation issuing the following sequence: a START, the
Identification byte with the R/W bit set to "0", an Address Byte, a
second START, and a second Identification byte with the R/W bit
set to "1". After each of the three bytes, the ISL78419 responds
with an ACK; then the ISL78419 transmits the Data Byte. The
master then terminates the read operation (issuing a STOP
condition) following the last bit of the Data Byte (see Figure 16).
The byte at address 02h determines if the Data Bytes being read
are from volatile or non-volatile memory.
Communication with ISL78419
There are 3 register addresses in the ISL78419, of which two can
be used. Address 00h and address 02h are used to control the
device. Address 01h is reserved and should not be used. Address
00h contains the non-volatile Initial Value Register (IVR), and the
volatile Wiper Register (WR). Address 02h contains only a volatile
word and is used as a pointer to either the IVR or WR.
Register Description: Access Control
The Access Control Register (ACR) is volatile and is at address
02h. It is 8 bits, and only the MSB is significant; all other bits
should be zero (0). The ACR controls which word is accessed at
register 00h as follows:
• 00h = Nonvolatile IVR
• 80h = Volatile WR
All other bits of the ACR should be written 0 or 1. Power-up
default for this address is 00h.
Register Description: IVR and WR
The output of the DCP is controlled directly by the WR. Writes and
reads can be made directly to this register to control and monitor
without any non-volatile memory changes. This is done by setting
address 02h to data 80h, then writing the data.
The non-volatile IVR stores the power-up value of the DCP output.
On power -up, the contents of the IVR are transferred to the WR.
To write to the IVR, first address 02h is set to data 00h, then the
data is written. Writing a new value to the IVR register will set a
new power-up position for the wiper. Also, writing to this register
will load the same value into the WR as the IVR. Therefore, if a
new value is loaded into the IVR, not only will the non-volatile IVR
change, but the WR will also contain the same value after the
write, and the wiper position will change. Reading from the IVR
will not change the WR, if its contents are different.
Writing a new value to the IVR
Write to ACR first
0 1 0 1 0 0 0 0A 0 0 0 0 0 0 1 0A 0 0 0 0 0 0 0 0A
Then, write to IVR
0 1 0 1 0 0 0 0 A 0 0 0 0 0 0 0 0 A D0 D7 D6 D5 D4 D3 D2 D1 A
Note that the WR will also reflect this new value since both registers get writen at the same time
D0:LSB, D7:MSB
Writing a new value to WR only
Write to ACR first
0 1 0 1 0 0 0 0A 0 0 0 0 0 0 1 0A 1 0 0 0 0 0 0 0A
Then, write to WR
0 1 0 1 0 0 0 0 A 0 0 0 0 0 0 0 0 A D0 D7 D6 D5 D4 D3 D2 D1 A
Note that the IVR value will NOT change
D0:LSB, D7:MSB
Reading from IVR
Write to the ACR first
0 1 0 1 0 0 0 0A 0 0 0 0 0 0 1 0A 0 0 0 0 0 0 0 0A
Then set the IVR address
0 1 0 1 0 0 0 0A 0 0 0 0 0 0 0 0A
Read from the IVR
0 1 0 1 0 0 0 1 A D0 D7 D6 D5 D4 D3 D2 D1
Example 2
Reading from the WR
Write to the ACR first
0 1 0 1 0 0 0 0A 0 0 0 0 0 0 1 0A 1 0 0 0 0 0 0 0A
Then set the WR address
0 1 0 1 0 0 0 0A 0 0 0 0 0 0 0 0A
Read from the WR
0 1 0 1 0 0 0 1 A D0 D7 D6 D5 D4 D3 D2 D1
FIGURE 19.
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FN8292.2
January 24, 2014