Nordic 3 - Low-Power Accelerometer Circuit

5 Hardware description: Smart Remote 3 DK add-on
Doc. ID 4374_139 v1.1
Page 33
C46
100nF
I2C_DATA
I2C_CLK
SX1509_RESET
I2C address: 0x3E
C48
100nF
C47
100nF
VCC
KEYIN_1
KEYIN_2
KEYIN_3
KEYIN_4
KEYIN_5
KEYIN_0
KEYOUT_1
KEYOUT_2
KEYOUT_3
KEYOUT_4
KEYOUT_5
KEYOUT_6
KEYOUT_7
KEYOUT_0
GND
3
I/O 2
1
VCC1
4
I/O 3
2
I/O 0
27
I/O 1
28
I/O 4
5
I/O 5
6
I/O 6
7
I/O 7
8
U7A
SX1509BIULTRT
13
14
15
16
19
20
21
22
GND
17
VCC2
18
U7B
SX1509BIULTRT
VDDM
12
GND
29
SDA
24
SCL
25
INT
9
RESET
23
ADDR0
26
ADDR1
10
OSCIO
11
U7C
SX1509BIULTRT
R26
100k
VCC
VIO
SB29
SB30
SB31
SB36
WU_IRQ
I/O 8
I/O 9
I/O 10
I/O 11
I/O 12
I/O 13
I/O 14
I/O 15
Figure 19: Keypad matrix I/O expander
5.3.3 Low-power accelerometer circuit
To obtain low power consumption and long battery lifetime, a low-power three-axis accelerometer (U3) has
been added to the remote control.
See below for the schematic. See also Intelligent power saving on page 24.