34701 datasheet(27/38 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

34701

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

DATA Definition

The DATA field in the single Data Transfer contains one or

several Command Bytes. The Command Byte identifies the

kind of operation required by the master to be performed and

has two fields, as illustrated in Figure 23:

1. Address field

2. Value field

The address field is selected from the list in Table 7.

Figure 23. Command Byte

Refer to Table 8, page 27, which summarizes the value

field definitions for the entire set of operation options.

Security in Writing Commands

To improve the security level, a so-called first command is

defined to initiate each write communications. The first

command identifies the operation, which is executed by the

following Command Byte.

A first command has the address field equal to the related

operation one, followed by a null value field (all zeros).

Table 9 summarizes first command definitions. The master

sends the first command before the Command Byte for the

intended operation.

VOLTAGE MARGINING OPERATION

After starting the communication in Writing mode, the

master sends the first command followed by the specific

Command Byte to set the required voltage margining for

either the LDO or the switcher (see Figure 24). To achieve a

simultaneous set for both LDO and switcher, two specific

commands must be issued in sequence after the first

command, one for each supply.

Table 7.

Address Field Definitions

Address Field

Operation

Write

001

Voltage Margining

011

Watchdog

Table 8.

Command Byte Definitions

Operation

Address

Value

Action

Voltage Margining

(As a 2nd

Command Byte)

100000

1st Command

0000

Output

Nominal

0001

+ 1.0%

0010

+ 2.0%

0011

+ 3.0%

0100

+ 4.0%

LDO Output: x=0

0101

+ 5.0%

Switcher Output

x=1

0110

+ 6.0%

0111

+ 7.0%

1000

- 1.0%

1001

- 2.0%

1010

- 3.0%

1011

- 4.0%

1100

- 5.0%

1101

- 6.0%

1110

- 7.0%

D6 D5 D4 D3

D1 D0

Address Field

Value Field

Bits

MSB

LSB

Watchdog

Programming

(As a 2nd

Command Byte)

01100000

1st Command

01100000

WD OFF

(24)

01101000

WD 1280 ms

Wind. OFF

01101001

WD 320 ms

Wind. OFF

01101010

WD 80 ms

Wind. OFF

01101011

WD 20 ms

Wind. OFF

01101100

WD 1280 ms

Wind. ON

01101101

WD 320 ms

Wind. ON

01101110

WD 80 ms

Wind. ON

01101111

WD 20 ms

Wind. ON

Notes

24.

The Watchdog timer is turned ON automatically after

receiving any other valid command byte changing watchdog

time.

Table 9.

First Command Definitions

First Command

Operation

001 00000

Voltage Margining

011 00000

Watchdog Programming

Table 8.

Command Byte Definitions

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