SI4464 datasheet(44/56 Pages) SILABS

44 / 56 page

Si4464/63/61/60

Rev 1.2

8.3. Temperature, Battery Voltage, and Auxiliary ADC

The Si446x family contains an integrated auxiliary ADC for measuring internal battery voltage, an internal

temperature sensor, or an external component over a GPIO. The ADC utilizes a SAR architecture and achieves

11-bit resolution. The Effective Number of Bits (ENOB) is 9 bits. When measuring external components, the input

voltage range is 1 V, and the conversion rate is between 300 Hz to 2.44 kHz. The ADC value is read by first

sending the GET_ADC_READING command and enabling the inputs that are desired to be read: GPIO, battery, or

temp. The temperature sensor accuracy at 25 °C is typically ±2 °C.



Command Stream



Reply Stream



Parameters



TEMPERATURE_EN

0 = Do not perform ADC conversion of temperature. This will read 0 value in reply TEMPERATURE.

1 = Perform ADC conversion of temperature. This results in TEMP_ADC.

Temp (°C) = TEMP_ADC[15:0] x 568/2560 – 297



BATTERY_VOLTAGE_EN

0 = Don't do ADC conversion of battery voltage, will read 0 value in reply BATTERY_ADC

1 = Do ADC conversion of battery voltage, results in BATTERY_ADC. Vbatt = 3*BATTERY_ADC/1280



ADC_GPIO_EN

0 = Don't do ADC conversion on GPIO, will read 0 value in reply

1 = Do ADC conversion of GPIO, results in GPIO_ADC. Vgpio = GPIO_ADC/GPIO_ADC_DIV where

GPIO_ADC_DIV is defined by GPIO_ATT selection.



ADC_GPIO_PIN[1:0] - Select GPIOx pin. The pin must be set as input.

0 = Measure voltage of GPIO0

1 = Measure voltage of GPIO1

2 = Measure voltage of GPIO2

3 = Measure voltage of GPIO3



UDTIME[7:4] - ADC conversion Time = SYS_CLK / 12 / 2^(UDTIME + 1). Defaults to 0xC if ADC_CFG is 0.

GET_ADC_READING

Command

765

CMD

0x14

ADC_EN

0 TEMPERATURE_EN BATTERY_VOLTAGE_EN ADC_GPIO_EN ADC_GPIO_PIN[1:0]

ADC_CFG

UDTIME[3:0]

GPIO_ATT[3:0]

GET_ADC_READING Reply

7654

3210

CTS

CTS[7:0]

GPIO_ADC

GPIO_ADC[15:8]

GPIO_ADC

GPIO_ADC[7:0]

BATTERY_ADC

BATTERY_ADC[15:8]

BATTERY_ADC

BATTERY_ADC[7:0]

TEMP_ADC

TEMP_ADC[15:8]

TEMP_ADC

TEMP_ADC[7:0]

RESERVED

Reserved

RESERVED

Reserved

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