34701 datasheet(28/38 Pages) FREESCALE

28 / 38 page

Analog Integrated Circuit Device Data

Freescale Semiconductor

34701

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

Figure 24. Voltage Margining Programming

(One Supply Only)

Note:

x bits, which set the voltage margining value are

defined in Table 8.

WATCHDOG PROGRAMMING OPERATION

For watchdog operation control, the master periodically

sends a watchdog first command followed by a command

byte selecting, or confirming, the watchdog period according

to the options listed in Table 8. See Figure 25 for the

watchdog timer programming command example.

The internal watchdog timer is turned ON by receiving a

valid Watchdog Programming command (after receiving the

Watchdog Programming First Command), and it is cleared

each time the next Watchdog Programming command is

written into the device, provided it arrives during the window

open time. Thus, the Watchdog Programming command

clears the timer and sets the new timing conditions at the

same time. The Watchdog Programming First Command

01100000 sent twice shuts the timer OFF, and the watchdog

function is disabled. Any other valid watchdog command

turns the timer ON again.

Figure 25. Watchdog Timer Programming

Note:

x bits, which set the watchdog timer value are

defined in Table 8, page 27.

Communication Stop

Only the master can terminate the data transfer by issuing

a STOP condition. The slave waits for this condition to

resume its initial state waiting for the next START condition

(see Figure 26).

COMPLETE DATA TRANSFER EXAMPLES

The master device controlling the I2C bus always starts

addressing a 34701 slave IC in writing mode (R/W = 0) to

enable it to write a Command Byte just after receiving the

address acknowledge sent by 34702. I2C bus protocol

defines this circumstance as a master-transmitter and slave-

receiver configuration.

Figure 27 illustrates a communication beginning with the

slave address, the first command for voltage margining, and

a third byte containing the address field 001 and the value

field 00101 corresponding with the LDO fifth setting (LDO

output voltage = +5% above its nominal value). If a

simultaneous setting for switcher is needed, a fourth byte

should be included before the STOP condition (P); for

instance, 001 11100 to set the switcher in its twelfth setting

(switcher output voltage = -5% below its nominal value) - see

Figure 28.

The example of data transfer setting the Watchdog timer is

shown in the Figure 26.

Figure 26. Data Transfer Example - Watch Dog Timer

Setting.

Figure 27. Data Transfer Example - LDO Voltage

Margining

0 0 0 0 0

First Byte for Voltage Margining

Command Byte

Ack

0 0 0 0 0

First Byte for Watchdog Programming Command Byte

Ack

START

Slave Address

Write

First Command for Watchdog Programming

Address Field Value Field:

Time-out WD = 320 ms

STOP

Ack

0Ack

Ack

011

A3 A2 A1

(Window OFF)

START

Slave Address

Write

First Command for Voltage Margining

Address Field Value Field = LDO

5th Setting

STOP

Ack

0Ack

Ack

A3 A2 A1

34701 датащи(PDF) 28 Page - Freescale Semiconductor, Inc

34701 датащи(HTML) 28 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

датащи скачать

ссылки URL