ak4184 AKM Semiconductor, Inc., ak4184 Datasheet - Page 28

• Manufacturer Part Number: ak4184
• Description: Tsc With Keypad Scanner And Gpio Expander
• Manufacturer: AKM Semiconductor, Inc.

L
The AK4184 contains an oscillator and a PWM control circuit for controlling the brightness of an LED by modulating
the “on” time. The brightness is determined by the PWM basic frequency (f
divides the internal oscillator frequency (fosc) and modulates this output. The range of PWM frequency (fpwm) is
80Hz minimum. The modulating range is provided by 32 duty cycle steps from the PWM logic controller. The output
control is determined by the PACT bit. The duty cycle width of the PWM frequency is controlled by the BRV and
DIV bits. The PWM signal stays constant on normal mode until duty cycle, PWM frequency changed.
The output type is possible to select either CMOS or Open Drain, set by the LPU bit. After reset, the PWM block is in
power-down state and the BRCONT pin outputs a “L” level.
Example BRV [4:0] =11H setting
L
Addr
MS0603-E-00
18H
PWM Control Register (PAGE 1)
Internal
PWM
Counter
LED contrast control
BRCONT
PWMCTRL
14:13
12:8
Bits
Name
5:3
2:0
15
7
6
0
PACT
Name
BRV
LPU
DIV
Oscillator
1
MSB
LPU
D15
2
Output type Open drain / CMOS
0: CMOS type (default)
1: Open Drain type
Reserved
Bright Control Value
The period of “H” output level is (control value + 1) cycle in unit of (fpwm/32)
Reserved
Oscillator and PWM Logic Controller Power Up
0:Power Down State(default)
1:Normal mode(Oscillator power up and enable output)
Reserved
PWM clock divider index
fpwm(typ.)=fosc/2
D14
3
0
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8
f
osc
Duty Cycle BR[4:0] =11H
PWM frequency(f
D13
0
9
Table 35. PWM Control Register Format
10
Figure 16. PWM output waveform
2
Table 36. PWM Control Register
Divider
D12
(DIV[2:0]+7)
Figure 15. PWM output block
11
[DIV + 7]
12 13 14
D11
BRV[4:0]
pwm
D10
) = fosc / 2
28
f
pwm
15
Description
D9
16 17
PWM Logic
(DIV[2:0]+7)
Controller
D8
18
D7
0
pwm
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8
) and duty cycles. The PWM block
PACT
D6
24 25
f
brcont
D5
0
26
BRCONT
27
D4
0
28
D3
0
29 30
D2
DIV[2:0]
2007/04
31
D1
[AK4184]
0
LSB
D0