CD1020 datasheet(44/56 Pages) NXP

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NXP Semiconductors

CD1020

7.10.21 Enter low-power mode

Low-power mode (LPM) is used to reduce system quiescent currents. Low-power mode may be entered only by sending the low-power

command. When returning to normal mode, all register settings is maintained.

The Enter Low-power mode register is write only and has the effect of going to LPM and beginning operation as selected (polling, interrupt

timer). When returning form low-power mode, the first SPI transaction will return the Fault Status and the intflg bit set to high, as well as

the actual status of the Input pins.

7.10.22 AMUX control register

The analog voltage on switch inputs may be read by the MCU using the analog command (Table 34). Internal to the CD1020 is a 22-to-1

analog multiplexer. The voltage present on the selected input pin is buffered and made available on the AMUX output pin. The AMUX

output pin is clamped to a maximum of VDDQ volts regardless of the higher voltages present on the input pin. After an input has been

selected as the analog, the corresponding bit in the next MISO data stream is logic [0].

Setting the current to wetting current (configurable) may be useful for reading sensor inputs. The MCU may change or update the analog

select register via software at any time in normal mode. The analog select defaults to no input.

Table 33. Enter low-power mode command

SPI data bits [23 – 0]

[31–25]

[24]

bits [23 – 16]

0011_100

0000_0000

bits [15 – 8]

0000_0000

bits [7 – 0]

0000_0000

MISO return word

—

Table 34. Slow polling SG register

R/W

SPI data bits [23 – 0]

[31–25]

[24]

bit 23

bit 22

bit 21

bit 20

bit 19

bit 18

bit 17

bit 16

0011_101

0/1

Unused

Default on POR

0000

000

bit 15

bit 14

bit 13

bit 12

bit 11

bit 10

bit 9

bit 8

Unused

0000

000

bit 7

bit 6

bit 5

bit 4

bit 3

bit 2

bit 1

bit 0

Unused

asett0

asel[5–0]

0000

000

MISO return word

bit [23]

bit [22]

bits [21 – 0]

0011_101[R/W]

FAULT

STATUS

INTflg

Table 35. AMUX current select

asett[0]

Zsource

hi Z (default)

1IWET

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