AN4440 datasheet(13/36 Pages) STMICROELECTRONICS

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AN4440

RFFE normal modes

3.2

Trigger mode

3.2.1

Purpose

When several PTICs are implemented in a mobile phone, it can be necessary to change all

or at least more than one DAC value simultaneously, for example, to re-match the antenna

when the band or use case changes. The basic mode updates the DAC value immediately

after each frame, thus DAC values are sequentially updated. The trigger mode provides a

solution for storing the DAC values without updating them and then updates simultaneously

all DAC outputs when the trigger occurs.

3.2.2

Methodology

•

1st step: trigger mode activation - trigger mask to 0 in register 28

•

2nd step: DAC values program: identical to basic mode but no change will occur on the

outputs. These values are stored in the shadow registers.

•

3rd step: trigger - set trigger bits to 1 in register 28 - Values are transferred from the

shadow registers to DAC. All selected DAC values are updated simultaneously.

Example 3

First step: activate trigger mode

Active trigger mask bits (in register 28): Reset bits D3, D4 and D5.

Figure 10. Active trigger mask bits register

Second step: program several DACs

Program DAC A for 15.6 V and DAC B for 13.2 V

DAC A corresponds to register 2, 15.6 V -> 96d = 01100000h

Figure 11. RFFE frame for 15.6 V on DAC A

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