
Rev.1.10
- 13 -
I
FUNCTIONAL DESCRIPTION
1.
3-wire Serial Interface
1-1. Data Transfer Summary
SCK
CSB
DATA
D0
0
D1
1
D2
2
D3
3
D4
4
D5
5
D6
6
D7
7
D8
0
D9
1
D10
2
D11
3
D12
4
D13
5
D14
6
D15
7
All data transfers are initiated by driving the CSB input low. The CSB input serves two functions. First, CSB turns on the
control logic which allows access to the shift register for the address/command sequence. Second, the CSB signal provides a
method of terminating data transfer. A clock cycle is a sequence of a falling edge followed by a rising edge. For data inputs,
data must be valid during the rising edge of the clock.
All data transfer terminates if the CSB input is high. Data transfer is illustrated as above.
1-2. Command Byte
7
6
5
4
3
2
1
0
D7
D6
D5
D4
D3
D2
D1
D0
The Command byte is shown as above. Each data transfer is initiated by a command byte.
The LSB (bit zero) must be a logic zero. An any data for each of bit six and bit seven which might be zero or one, is ignored.
Bits one through five specify the designated registers to be input.
The command byte is always input starting with the LSB (bit zero).
1-3. Data Input
Following the eight SCK cycles that input a write command byte, a data byte is input on the rising edge of the next eight SCK
cycles. And any successive instruction set which consists of command byte and data byte is allowable. The data byte is always
input starting with the LSB (bit zero).
1-4. Regulator Switch
Each of regulators can be enabled or disabled independently. In the VR switch register, designations for each of seven
regulators' ON/OFF can be written to bit zero through six. Bit seven is ignored.
1-5. Battery Monitor / LED Drivers / Ringer Controller
An analog output of cell voltage monitor is available with enable switch. Three of constant voltage outputs for LEDs and a
ringer controller can be independently ON/OFF. All of those enable switches are controlled by output port register. Bit zero
and one through three are for enable switch of battery monitor and LED drivers respectively.
Bit four through six is input digit of electronic volume for ringer controller, bit four is defined as the LSB. Bit seven is enable
switch for ringer controller.
1-6. Programmable Voltage Regulators /VR3, 4
The output voltage of VR3 and VR4 can be controlled externally by written data to the VR3/VR4 output registers.
VR3 outputs from 0.5V to 2.492V, VR4 outputs from 1.008V to 3.0V with eight bit resolution for each. Bit zero of each
register is the LSB.