NRF9E5 Datasheet, PDF (30/104 Pages) List of Unclassifed Manufacturers – 433/868/915MHz RF Transceiver with Embedded 8051 Compatible Microcontroller and 4 Input, 10 Bit ADC

PRODUCT SPECIFICATION
nRF9 E5 Single Chip Transceiver with Embedded Microcontroller and ADC
10.2 AD Converter Usage
10.2.1 Measurements with External Reference
When VFSSEL is set to 1 and CHSEL selects an input AINi (i.e. AIN0 to AIN3), the
result in ADCDATA is directly proportional to the ratio between the voltage on the
selected input, and the voltage on pin AREF:
V _AINi
= V _AREF ⋅
ADCDATA
2^N
and for differential measurements a similar equation apply:
V _AINi
−V _AIN0
= V _AREF ⋅
ADCDATA
2^N
− 2 ^{(N −1)}
Where N is the number of bits set in RESCTRL
This mode of operation is normally selected for sources where the voltage is depending
on the supply voltage (or another variable voltage), as shown in Figure 7 below. The
resistor R1 is selected to keep AREF = 1.5V for the maximum VDD voltage.
SUPPLY
R1
R2
R3
VDD
AREF
nRF9E5
AIN0
AIN1
Figure 7 Typical use of AD with 2 ratiometric inputs.
Main office: Nordic Semiconductor ASA - Vestre Rosten 81, N-7075 Tiller, Norway -Phone [phone] - Fax [phone]
Revision: 1.1
Page 30 of 104
June 2004