AK8456

[AK8456]
AK8456
3 channel input 16bit 30MSPS Video ADC with LED driver
1. General Description
AK8456 is an AFE for three channels contact image sensor (CIS). AK8456 has offset adjusting DAC,
digital programmable gain amplifier (PGA) and LED drivers. AK8456 is suitable for multi-function
printer and image scanner.
2. Feature











Input Block
Channel number
3 channel (1 channel mode is available)
Range
1.3Vpp (min.)
Gain
0dB/6dB
ADC
Maximum conversion ratio
30MSPS
10MSPS/ch @ 3-channel mode
30MSPS/ch @ 1-channel mode
Resolution
16bit (Straight binary code/Gray code)
Black correction DAC
Range
369mV (Equivalent input voltage) ＜±250mV(min.)＞
Resolution
6bit
Digital PGA
Range
0dB~18dB
Resolution
8bit
Output Format
8bit × 2
LED Current
67.2mA/ch (typ.) @ Maximum setting
Adjustable by 12.5% resolution channel independently
CPU I/F
3-wire serial interface
Supply Voltage
AFE: 3.3V0.3V, LED driver: 4.5V~5.7V
Power Consumption
190 mW (typ.)：Except LED drive current.
Operating Temperature 0C~70C
Package
36pin QFN (Exposed Die Pad), 0.4mm pitch, 5mm5mm
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3. Table of Contents
1. General Description ........................................................................................................................1
2. Feature............................................................................................................................................1
3. Table of Contents............................................................................................................................2
4. Block diagram and Functions ..........................................................................................................3
5. Pin allocation and Functions............................................................................................................5
6. Absolute Maximum Ratings ............................................................................................................7
7. Recommended Operating Conditions ..............................................................................................7
8. Electrical Characteristics .................................................................................................................7
9. Functional Description ..................................................................................................................17
10. Register Map...............................................................................................................................23
11. External Circuit Example ............................................................................................................29
12. Package.......................................................................................................................................31
13. Important Notice .........................................................................................................................32
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4. Block diagram and Functions
OVSS
Serial I/F
OVDD
DVO
SDATA
POR
SDCLK
RESETB
Clock Gen.
SDENB
AVO
LDO_A
AVDD
ADCK
SHD
ISET
VRP
VDC
Reference Voltage
LDO_D
CMOS Output
Analog
PGA
CISIN0
6
SHD
DAC
D0
D1
D2
Analog
PGA
CISIN1
SHD
DAC
6
3 to 1 MUX
AFE ch0
16bit
16
30MSPS
Digital
PGA
16
D3
8
Output
Control
ADC
D4
D5
AFE ch1
D6
LED
driver
LED
Cont.
Analog
PGA
CISIN2
6
SHD
DAC
D7
AFE ch2
LVDD
LVSS
LVSS
LED_B
LED_G
LEDEN_B
LEDEN_G
LEDEN_R
LED_R
LVDD
Fig.1 Block diagram
 Input Block
AK8456 is available for CIS whose polarity is positive. The voltage difference between CISIN0~2
input signal and sensor reference voltage VDC is sampled. VDC is input externally and also is able to
generate internally. There are three channel mode and one channel mode. In one channel mode, sensor
signal input pin is CISIN0.
 DAC 6bit DAC
Offset adjust is excused by adding DAC output voltage to input signal. DAC resolution is six bit and
output range is 369mV (typ.). 100mV (max.) out of 369mV is used to cancel LSI internal offset.
Therefore effective range for correcting signal offset is 269mV (typ.).
 Sample and Hold Block
S/H
The voltage difference between CISIN0~2 input signal and sensor reference voltage VDC is sampled
at sample and hold block. Gain at sample and hold block is selected from 0dB and 6dB.
 Multiplexor
MUX
Due to process three channels in a time-division, MUX selects one channel out of three channels in
order.
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 ADC
After offset adjust, the ADC convert analog signal level to digital data. The ADC has 16-bit resolution
and 30MSPS maximum conversion ratio. The output code is straight binary, 0000h corresponds to
black signal and FFFFh corresponds to white signal.
 Digital PGA
The digital PGA amplifies A/D data. Its gain range is 0dB~18dB and gain resolution is 8bit.
 Output Control Block
The output control block converts 16-bit width data to two 8-bit width data. Higher 8-bit is output at
ADCK rising edge and lower 8-bit is output at ADCK falling edge. Gray code output is possible too
by register setting.
 Reference Voltage Generation Block
Reference Voltage
This block generates internal reference voltage VRP, sensor reference voltage VDC and LDO
reference voltage.
 Internal Clock Generation Block
Clock Gen
This block generates internal pulses using A/D clock ADCK and sampling pulse SHD.
 LED Driver Control Block
LED Control
This block controls LED switching and LED current. LED current is adjustable from 100% to12.5%
by 12.5% step channel independently. 100% current is 67.2mA per channel.
 Serial Interface Block
Serial I/F
Control registers are written and read through 3-wire serial interface.
 Low Dropout Voltage Regulator
LDO
The LDO generate 1.8V supply from 3.3V of AVDD. The 1.8V is used for internal circuit. There are
two LDO for analog circuit and digital circuit.
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5. Pin allocation and Functions
D7 19
D6 20
D5 21
D4 22
OVDD 23
OVSS 24
D3 25
D2 26
D1 27
18 LED_B
D0 28
DVO 29
17 LVSS
ADCK 30
16 LED_G
SHD 31
AVDD
15 LVSS
AK8456
Top View
32
14 LED_R
AVO 33
13 LVDD
VRP 34
12 LEDEN_B
ISET 35
11 LEDEN_G
VDC 36
10 LEDEN_R
9 SDATA
SDENB
8 SCLK
7
6 RESETB
5 CISIN2
4 AVDD
3 CISIN1
2 AVDD
1 CISIN0
Note)
Connect under side thermal exposed PAD with AVSS.
Fig.2 Pin Layout
 Pin Functions
No.
Name
IO
1
CISIN0
I
---
Sensor Signal Input
2
AVDD
P
---
Analog Supply
3
CISIN1
I
---
Sensor Signal Input
4
AVDD
P
---
Analog Supply
5
CISIN2
I
---
Sensor Signal Input
6
RESETB
I
---
Reset Input, Active Low
Include Pull-up Resistance 100k (typ.)
7
SDENB
I
---
Serial Interface Data Enable
8
SCLK
I
---
Serial Interface Clock Input
9
SDATA
10
LEDEN_R
IO
I
Standby Description
(note 2)
High-Z Serial Interface Data Input and Output
---
LED_R Control Signal Input
Include Pull-down Resistance 50k (typ.)
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11
LEDEN_G
I
---
LED_G Control Signal Input
Include Pull-down Resistance 50k (typ.)
12
LEDEN_B
I
---
LED_B Control Signal Input
Include Pull-down Resistance 50k (typ.)
13
LVDD
P
---
LED Driver Supply (5V)
14
15
LED_R
LVSS
O
P
High-Z LED Driver Output R
--LED Driver Ground
16
LED_G
O
High-Z LED Driver Output G
17
LVSS
P
18
LED_B
O
19
D7
O
Low
A/D Data Output (note 1) (Upper bit)
20
D6
O
Low
A/D Data Output (note 1)
21
D5
O
Low
A/D Data Output (note 1)
22
D4
O
Low
A/D Data Output (note 1)
23
OVDD
P
---
24
25
OVSS
D3
P
O
--Low
A/D Data Output Buffer Ground
A/D Data Output (note 1)
26
D2
O
Low
A/D Data Output (note 1)
27
D1
O
Low
A/D Data Output (note 1)
28
D0
O
Low
A/D Data Output (note 1) (Lower bit)
29
DVO
O
1.8V
Digital LDO Output pin (1.8V) Keep DVO open.
30
ADCK
I
---
ADC Clock
31
SHD
I
---
Sampling Clock
32
AVDD
P
---
Analog Supply (LDO Supply)
33
AVO
O
Low
Analog Block LDO Output Voltage Monitor (1.8V)
Connect 1μF capacitor between AVO and AVSS.
34
VRP
O
Low
ADC Reference Voltage
Connect stabilize capacitor 1F via AVSS
35
ISET
I
---
Resistance for Reference Current Setting
36
VDC
IO
Tab
AVSS
P
---
LED Driver Ground
High-Z LED Driver Output B
A/D Data Output Buffer Supply (3.3V)
High-Z CIS Reference Voltage
Connect stabilize capacitor 1F via AVSS
---
Analog Ground
(note 1) Open drain output in cascade output mode
(note 2) Standby is defined as the condition that power down bit NPD=0 after reset.
(note 3) I:Input / O:Output / P:Power supply
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6. Absolute Maximum Ratings
AVSS=OVSS=LVSS=0V. All voltages are based on ground.
Item
Symbol
Min.
Max.
Unit
Analog Supply
Digital Output Buffer Supply
LED Driver Supply
AVDD
OVDD
LVDD
-0.3
-0.3
4.6
4.6
6.2
V
V
V
Input Voltage
VINA
-0.3
AVDD+0.3
V
Storage Temperature
Tstg
65
150
C
-0.3
Remarks
Operation at or beyond these limits may result in permanent damage to the device.
Normal operation is not guaranteed at these extremes.
7. Recommended Operating Conditions
AVSS=OVSS=LVSS=0V. All voltages are based on ground.
Item
Symbol
Min.
Typ.
Max.
Unit
Analog Supply
Digital Output Buffer Supply
LED Driver Supply
AVDD
OVDD
LVDD
3.0
3.0
4.5
3.3
3.3
5.0
3.6
3.6
5.7
V
V
V
Operational Temperature
Ta
0
70
C
Remarks
Normal operation is guaranteed at AVDD voltage = OVDD voltage.
All supplies must be power-up. Don’t power off partial supplies for saving consumption.
If LEDD function is unnecessary. LVDD pins can connect VSS level.
8. Electrical Characteristics
 Reset timing
Fig.3
In case of internal power on reset
Prise
Prise
Poff
0.9×AVDD
Power
0.1×AVDD
Rtime
Internal Reset signal
(note) When using a power on reset circuit, the RESETB pin must connect the capacity of 0.33μF to
AVSS.
(VDD：AVDD=OVDD =3.0~3.6V, Ta=0~70C)
Item
Symbol Min. Typ. Max.
unit
Condition
VDD rise time
Prise
0.01
10
ms
VDD 0V period
Poff
300
ms
0V peripd
The waiting time of the
Rtime
100
ms
reset cancellation
* Start all powers at the same time.
* When VDD_0V_period can not meet this condition, Because a register isn't reset, this
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doesn't work normally. And the over-current may flow through VDD. It is same when
using an external reset pin, too.
Fig.4
In case of external power on reset pin
Trst1
0.9×AVDD
Power
0.1×AVDD
Trst2
Prise
RESETB
Item
VDD rise time
Reset period 1
Reset period2
0.1AVDD
Symbol
Prise
Trst1
Trst2
(VDD：AVDD=OVDD=3.0~3.6V, Ta=0~70C)
Typ. Max.
unit
Condition
ms
μs
μs
Min.
0.01
100
100
*When RESETB:Low, LDO for AFE power and LDO for digital power are power downed. The
time of digital LDO power-off is 6μs. (The time which becomes lower than 20% of 1.8 V)
 DC Characteristics
(AVDD=OVDD=3.0V~3.6V, Ta= 0~70C)
Item
Symbol
Pin
High Input Voltage
VIH
Note
1,2,3
Low Input Voltage
VIL
Min.
Max.
0.7×AVDD
Unit
Remarks
V
High Level output resister
Low Level output resister
ROH1
ROL1
Note
1,2,3
Note 4
Note 4
0.3×AVDD
V
100
100
Ω
Ω
High Output Voltage
Low Output Voltage
VOH
VOL
Note 5
Note 5
0.8×AVDD
0.2×AVDD
V
V
Input Leakage
ILKG1
Note 1
10
10
A
Input Leakage
ILKG2
Note 2
45
10
A
Input Leakage
ILKG3
Note 3
10
90
A
Input Leakage
ILKG4
Note 4
10
10
A
Input Leakage
ILKG5
Note 6
10
10
A
Output Leakage
OLKG
Note 7
10
10
A
IOH=-1mA
IOL=1mA
High-Z
(Note1) ADCK, SHD, SCLK, SDATA (Input), SDENB,
(Note2) RESETB
(Note3) LEDEN_R, LEDEN_G, LEDEN_B
(Note4) D0~D7
(Note5) SDATA (Output)
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(Note6) CISIN0~2
(Note7) LED_R/G/B (LED Driver OFF)
 AFE Block Analog Characteristics 1
(Unless other specified, AVDD=OVDD=3.3V, LVDD=5.0V, Ta=25C, ADCK=30MHz)
Item
Sensor Reference
Level
ADC
Voltage
Symbol
VDCE
VDCI1
VDCI2
Reference VRP
Conditions
Reference Voltage
External Input Range
Internal Voltage
Internal Voltage
min
typ
max
0.8
0.9
1.0
1.0
1.1
1.2
1.1
1.2
1.4
1.5
1.6
1.3
1.5
5.5
6.0
Unit
V
V
V
V
Sample and Hold
Input Range
VI
Gain
GSH
Resolution
DRES
Range
DRNG
Differential
nonlinearity
DDNL
S/H Gain=0dB
Digital PGA Gain=0dB
S/H Gain=6dB setting
Offset Adjust DAC
Equivalent Input Level
Positive Direction
Negative Direction
DAC code conversion
300
-440
369
-369
-1
Vpp
6.5
dB
6
bit
440
-300
+1
mV
mV
LSB
Digital PGA
Maximum Gain
GMAX
Relative to 0dB setting
Step Width
GSTA
Monotonicity Guaranteed
0.001
18
dB
0.07
dB
ADC
Resolution
Differential
Non-Linearity
RES
DNL
Integral
Non-linearity
INL
CISIN~ADC
No missing code guaranteed
at
12bit
accuracy
(PGA=0dB)
CISIN~ADC
12bit accuracy
-1
16
+1
-16
16
bit
LSB
LSB
Noise, Internal Offset, Cross Talk
No Signal Noise
(Note 1)
NI
Gain=0dB
Gain=18dB
(S/H=6dB, PGA=12dB)
Internal Offset
(Note 2)
Cross Talk
VOFST
Gain=0dB
50
XTALK
(Note 3) PGA=0dB
-256
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32
LSBrms
50
mV
256
LSB
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 AFE Block Analog Characteristics 2
These specifications are defined under the condition external parts and their constants are in External
Circuit Example.
(AVDD=OVDD=3.0～3.6V, LVDD=4.5～5.7V, Ta=25C, ADCK=30MHz)
Current consumption
(note 4)
Normal operation
AVDD
37.4
51.2
mA
(note 5)
OVDD
8.6
25.5
mA
(note 6)
LVDD
6.2
8.4
mA
Stand By
ISTB
2.2
3
mA
These specifications are defined under the condition external parts and their constants are in External
Circuit Example.
(Note1) No signal noise is defined as sigma(σ) of ADC code deviation under no input signal.
(Note2) When no input signal is applied, ADC code changes from 0000h to 0001h between offset
DAC 50mV and offset DAC 50mV. The offset DAC cancels this internal offset as well as
signal offset. Thus adjust range for input signal offset is reduced by the internal offset.
(Note3) ADCK=30MHz, 3ch, PGA Gain of all channel is minimum. Cross talk is defined, as change
of output code when measured channel input is fixed and all other channel inputs is full-scale
 2dB step signal.
(Note4) ADCK=30MHz, Input -2dB of 1.5Vpp sine wave, 1MHz signal to three channels.
(Note5) Load Capacitance10pF
(Note6) @ LED_R=100%, LED_G=25%, LED_B=25% setting (except LED drive current)
 LED Driver Analog Characteristics
(Unless otherwise specified, AVDD=OVDD=3.3V, LVDD=5.0V, Ta=0C~70C,
ADCK=30MHz)
Item
Min.
Maximum LED Current
per Channel
Total Maximum
Current
60.5
LED
Typ.
67.2
Max.
73.9
100.8
Unit
Remarks
mA/ch ISET Resistance=8.2kΩ
LED_R/G/B Pin Voltage=2.0V
mA
5
5
%
LED_R/G/B Pin Voltage=2.0V
Dependence of LED
Current on LED_R/G/B
Pin Voltage
2.5
2.5
%
LED_R/G/B Pin’s Reference
Voltage = 2.0V
LED_R/G/B Pin Voltage
0.3
LVDD
1.1
V
Driving Current
LED Current
Accuracy
Setting
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 Switching Characteristics
No.
1
2
Item
ADCK Cycle (T)
ADCK Low Width
3
ADCK High Width
(Unless otherwise specified, AVDD=OVDD=3.0V~3.6V, Ta=0~70C)
Pin
Min.
Typ.
Max. Unit
Remarks
ADCK
33.3
2000
ns
ADCK
15
ns
ADCK
15
ns
3
6
1
3ch Normal Output
clocks 3ch Cascade Output
1ch Mode
ns
4
SHD Cycle
SHD
5
SHD Pulse Width
SHD
8
6
SHD Setup Time
（to ADCK）
SHD
2
ns
7
SHD Delay Time
（to ADCK）
SHD
10
ns
8
9
10
SHD Aperture Delay
D0~7 Delay
（to ADCK）
Pipeline Delay
(ADCK unit)
SHD
D7~D0
2.5
2
D7~D0
ns
10
11
Hold, Setup
ns
CL=10pF
(Note 1)
3ch Mode
clocks
1ch Mode
SHD=”H”
Prohibited
1T+10
3ch Normal Output
11
Region
(to
First
SHD
4T+10
ns
3ch Cascade Output
ADCK after SHD)
10
1ch Mode
0
8.2
12
D0~7 Enable Time
D7~D0
ns
Cascade Output
2.4
7.2
13
D0~7 Disable Time
D7~D0
ns
Cascade Output
These specifications refer to point crossing levels that defined in DC characteristics.
(Note1) Refer to points ADCK, D7~D0 cross 50% of supply voltage. This delay is under ADCK rise
time tr and fall time tf are 1.65ns.
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3ch Input, Normal Output
CISIN0~2
0
1
2
SHD
4
10 clock
ADCK
D7~D0
3
1
2
4
3
5
7
6
8
9
1
1
L ML ML ML ML ML ML ML ML ML ML ML ML ML ML
CISIN0 CISIN1 CISIN2 CISIN0 CISIN1 CISIN2


In D7~D0, L means lower 8 bits, M means upper 8bits.
Fig. 5

0
Whole Timing
Sampling Point
8
CISIN0(n)
CISIN1(n)
CISIN0~2
CISIN0(n+1)
CISIN1(n+1)
5
6
SHD
1
3
4
7
2
11
ADCK
9
D7~D0
9
MSB LSB MSB LSB MSB LSB MSB LSB MSB LSB MSB LSB MSB LSB
CISIN2(n5)
CISIN0(n4)
CISIN1(n4)
Fig.6
CISIN0(n3)
CISIN1(n3)
CISIN2(n3)
Details
tf
tr
ADCK
CISIN2(n4)
0.7AVDD
0.3AVDD
9
D7~D0
9
0.5OVDD
Fig.7
D0~D7 Delay
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3ch Input, Cascade Output
CISIN0~2
1
0
2
3
SHD
ADCK
D7~D0
#0
D7~D0
#1
M L M L M L
M L M L M L
CISIN0
M L
M L M L M L
M L M L M L
CISIN2
CISIN1
M L M L M L
CISIN0
2
1
M L M L M L
CISIN2
CISIN1
0
In D7~D0, L means lower 8 bits, M means upper 8bits.
Fig.8
Whole Timing
Sampling Point
8
CISIN0(n)
CISIN1(n)
CISIN2(n)
CISIN0~2
CISIN0(n+1)
CISIN1(n+1)
CISIN2(n+1)
6
5
SHD
1
2
ADCK
3
9
D7~D0
M
4
7
L
11
9
M
L
M
L
M
L
M
L
M
L
M
L
CISIN0 CISIN1 CISIN2
(n4)
(n4)
(n4)
Fig.9
tr
ADCK
Details
tf
0.7AVDD
0.3AVDD
12
9
D7~D0
9
13
0.5OVDD
Fig.10
D0~D7 Delay
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1ch Input
CISIN0
0
1
2
3
4
5
6
7
8
9
10
11
12
SHD
ADCK
D7~D0
L
M
L
M
L
M
10
L
9
M
L
M
8
L
M
7
L
M
6
L
M
5
L
M
4
L
3
M
L
M
2
L
M
1
L
0
M
L
1
In D7~D0, L means lower 8 bits, M means upper 8bits.
Fig.11 Whole Timing
Sampling Point
CISIN0(n+1)
8
CISIN0(n)
CISIN0
5
6
SHD
4
7
11
ADCK
9
D7~D0
3
9
MSB
2
1
LSB
MSB
CISIN0(n11)
LSB
CISIN0(n10)
Fig.12 Details
tr
ADCK
tf
0.7AVDD
0.3AVDD
9
D7~D0
9
0.5OVDD
Fig.13
D0~D7 Delay
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 Serial Interface Switching Characteristics
Sf
SDENB
Sr
Sdenh
0.7AVDD
0.3AVDD
Sf
Ssu
Sr
Shi
Slo
Sh2
0.7AVDD
0.3AVDD
SCLK
Ssu
SDATA
0.7AVDD
0.3AVDD
Sh
Scyc
input
Ssp
input
output
Sst
Fig.14
output
0.8AVDD
0.2AVDD
Sdl
Serial Interface Timing
(Unless otherwise specified, AVDD=OVDD=3.0V~3.6V, Ta=0~70C, CL=10pF)
Item
Clock Cycle
Symbol
Scyc
Condition
min.
Clock High Width
Shi
Above 70% of AVDD
40
ns
Clock Low Width
Slo
Under 30% of AVDD
40
ns
Setup Time
(to SCLK)
Ssu
40
ns
Hold Time
(to SCLK)
Sh
40
ns
SDENB Hold Time
(to SCLK)
Sh2
80
ns
Data Enable Delay
(to SCLK)
Sst
Data Output Delay
(to SCLK)
Sdl
Data Disable Delay
(to SDENB)
SDENB High Width
Ssp
High-Z→Data Out
typ.
max.
10
Unit
MHz
0
30
ns
0
30
ns
Data Out→High-Z
0
30
ns
Sdenh
Above 70% of AVDD
40
Rise Time
Sr
30%70% of AVDD
10
ns
Fall Time
Sf
70%30% of AVDD
10
ns
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[AK8456]
 LED Driver Switching Characteristics
(Unless otherwise specified, AVDD=OVDD=3.0V~3.6V, LVDD=4.5V~5.7V, Ta=0~70C)
Item
Symbol
LEDEN_R/G/B Setup Time
(to SHD)
tlens
15
ns
LEDED_R/G/B Hold Time
(to SHD)
tlenh
15
ns
min.
typ.
max.
0.7AVDD
LEDEN_R/G/B
tlenh
SHD
Conditions
0.3AVDD
tlens
tlenh
tlens
0.7AVDD
0.3AVDD
Fig. 15
Unit
LED driver switching characteristics
(Unless otherwise specified, AVDD=OVDD=3.0V~3.6V, LVDD=4.5V~5.7V, Ta=0~70C)
Item
Symbol Conditions
min.
typ.
max.
Unit
LED Current Rise Time
tlon
10
s
LED Current Fall Time
tloff
10
s
LEDEN_R/G/B
SHD
0.3AVDD
0.3AVDD
90%
LED_R/G/B Current
10%
tlon
Fig. 16
tloff
LED current timing
LED drivers are switched in LEDEN_R/G/B those are synchronized with SHD falling edge. Therefore,
if it can’t meet setup time or hold time of LEDEN_R/G/B, LED lighting time will be 1~2 pixels
change.
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[AK8456]

9. Functional Description
 Start Up
There is no restriction on order of turning on AVDD, OVDD and LVDD.
Please take a reset by hold RESETB low level when the power AVDD is turned on.
LEDEN_R/G/B must be low level during RESETB rises. User can access to the registers
after wait time that are shown in followed figures from power-up.
Fig.17
Not Use Power on Reset
AVDD (3.3V)
Internal Reference circuits (related to LDO) are
activated immediately. A few mA consumption
RESETB
LDO start
DVO
(LDO Output)
(1.8V)
Access to Register
Not available (Reset)
a few ms
Available
~1ms
LEDEN_R/G/B
LEDEN_R/G/B are must be all low when RESETB rise to
high.
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[AK8456]
Fig.18
Use Power on Reset
AVDD
100k
RESETB
0.33F
AK8456
Power on reset circuit is composed by pull-up resistance of RESETB and external capacitor. When
external capacitor is 0.33F, AVDD rise time must be less than 10ms to reset exactly. Staircase-like
supply voltage rising is not allowed.
Fig.19
Power on Reset timing
AVDD (3.3V)
Internal Reference circuits (related to LDO) are activated
immediately. A few mA consumption occurs.
RESETB
LDO start
DVO
(LDO Output) (1.8V)
Access to Register
Not available (Reset)
Available
~100ms
LEDEN_R/G/
LEDEN_R/G/B are must be all low when RESETB rise to high.
When down AVDD to 0V, RESETB level does not became 0V immediately because of charge
remaining in RESETB external capacitor. If up AVDD again before RESETB becoming 0V, power on
reset does not carry out. The time AVDD is 0V must be longer than 300ms for exact power on reset at
re-power up AVDD.
Please control the RESETB from outside without the use of a power-on reset if the above conditions
are not met. During power up AVDD, hold RESETB low level. Then raise RESETB to high level.
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[AK8456]
 Serial Interface
Control registers are accessed through serial interface. The control registers are readable.
If SDENB is low, it is possible to access registers. Input address and data into SDATA. SDATA is
captured by SCLK rising edge.
Write
The first bit of SDATA is 0, data is written to register. From second bit to fourth bit must be
0. From fifth bit to eighth bit are address bits. The fifth bit is most significant bit of address.
From ninth bit to sixteenth bit are data bit.
Data is written into register by rising edge of SDENB. If rising edge of SCLK is less than
sixteen, data isn't written into register. If rising edge of SCLK is more than seventeen, front
sixteen bits are effective.
SDENB
SCLK
SDATA
Fig.20
0
0
0
0
A3 A2 A1 A0 B7 B6 B5 B4 B3 B2 B1 B0
Write to Register
Read
The first bit of SDATA is 1, data is read from register. From second bit to fourth bit must be 0. From
fifth bit to eighth bit are address bits. The fifth bit is most significant bit of address. Data is output
from the SCLK falling after SCLK rising incorporating an eighth bit. SDATA pin is used as an input
again if SDENB become high level. If there is a SCLK 17 or more times, read data after the B0 is
output is 0.
SDENB
SCLK
SDATA
1
0
0
0
A3 A2 A1 A0 B7 B6 B5 B4 B3 B2 B1 B0
Input
Fig.21
Output
Input
Read from Register
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[AK8456]
 CIS Signal Input Channel Number Select
There are 3-channel mode and 1-channel mode as input channel number. Input channel
number is selected by register. In 1-channel mode, signal is input to CISIN0. At this time,
CISIN1 and CISIN2 can be connected to AVSS, or opened, or input dummy signal. Sample
and hold circuit and DAC of not used channels are power down.
Frequency of ADCK in 3-channel mode is three times the pixel frequency per channel. In
1-channel mode, ADCK frequency is equal the pixel frequency.
 CIS Reference Voltage
It is able to select to use internal voltage or to use externally input voltage as sensor
reference voltage by register. Input range of external voltage is from 0.8V to 1.2V. Internal
voltage is 1.0V (typ.) or 1.1V (typ.).
 Offset Adjustment
Offset adjustment is done by adding DAC output voltage to sensor signal. Resolution of
DAC is six bit, range is 369mV(typ.)/300mV(min.) in equivalent input voltage. 50mV
(max.) out of 369mV is used to cancel LSI internal offset. Therefore effective range for
correcting signal offset is 319mV(typ.)/250mv(min.).
The equivalent input voltage does not change even if set 6dB gain at sample and hold block.
VDC
Offset DAC
Vref
S/H
CISINn
Signal
Vsig
Reference
Vref
GND
Vsig
Internal
Reference
Level
Fig.22
+Max.(011111b)
369mV
369mV
Max.(100001b)
Offset adjustment
 Sampling
Sensor signal are sampled at SHD falling edge.
 Gain Adjustment
It is possible to amplify signals at sample and hold block. And it is possible to amplify A/D
output code by digital PGA. Gain of digital PGA is from 0dB to 18dB. Its resolution is 8bit.
 Output Format
Output Formal is straight binary. Gray code output is possible too.
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[AK8456]
A/D
16
Digital
PGA
16
16
Gray
Code
D15
G15
D14
G14
D13
G13
Gray code conversion
D12
G11
D10
G10
D8
Forward Backward
8
D7~D0
G12
D11
D9
16bit

Upper 8bit
Lower 8bit
G9
G8
Forward
Backward
D7
D15
D7
G7
G15
G7
D6
D14
D6
G6
G14
G6
D5
D13
D5
G5
G13
G5
D4
D12
D4
G4
G12
G4
D3
D11
D3
G3
G11
G3
D2
D10
D2
G2
G10
G2
D1
D9
D1
G1
G9
G1
D0
D8
D0
G0
G8
G0
Normal
Fig.23
Gray Code
Output format
 LED Driver
LED Driver controls LED current RGB independently. LED must be connected as anode
common. If LEDEN_R/G/B are high level, LED current are driven. If LEDEN_R/G/B are
low level, LED current are stopped. LEDEN_R/G/B are synchronized once by SHD
internally. Therefore if SHD is not input, LEDEN_R/G/B are not effective.
 LED Current Adjustment
The LED current can be adjusted in increments of 8.4mA to 67.2mA from 8.4mA channel
independently.
 LED Current Limit
AK8456 LED driver current limitation is 100.8mA (total:150% setting). With the
combination with “LEDEN_R/G/B pin logic” and LED drive current setting register value,
in case of the combination that the total of the current amount to flow through at the same
time exceeds 150%(100.8 mA), the LED drive current doesn't flow. For example, when
making "LEDEN_R/G/B" active at the same time and when the total of the LED drive
current set value exceeds 150%(100.8 mA), the LED drive current doesn't flow. On the other
hand, when making "LEDEN_R/G/B" active individually, the current flows.
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[AK8456]
 Cascade Output Mode
It is possible that connect two AK8456’s output pins to same 8bit bus by cascade output
mode. The cascade output mode is available only in 3-channle input mode. It becomes the
normal output regardless of the cascade mode register setting when the channel 1 input. If
use cascade mode, please release the power-down after setting the device ID and cascade
mode register.
Select the cascade mode in the register and set 0 in ID register of one and set 1 in ID register
of the other. Device of ID0 outputs the data before, ID1 devices will output the data then
refer to SHD pulse. D7~D0 become high impedance when these pins don’t output A/D data.
D7~D0 are open drain output in cascade mode. Please connect pull-up resistance to each
data output pin. Maximum sampling rate in cascade mode is 5MSPS/ch.
AK8456
#0
D7~D0
8
SCLK, SDATA
2
SDENB1
8
Control
IC
AK8456
#1
D7~D0
8
SCLK, SDATA
2
SDENB2
CISIN0~2
0
1
3
2
SHD
ADCK
D7~D0
#0
D7~D0
#1
M L M L M L
M L M L M L
CISIN0
M L
M L M L M L
M L M L M L
CISIN2
CISIN1
M L M L M L
CISIN0
Fig.24
M L M L M L
CISIN2
CISIN1
Cascade mode explanation
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[AK8456]
10. Register Map
0h
Register
Name
CNTRL1
1h
2h
OFST0
OFST1
CISIN0 Offset Setting
CISIN1 Offset Setting
3h
4h
OFST2
GAIN0
CISIN2 Offset Setting
CISIN0 Gain Setting
5h
6h
GAIN1
GAIN2
CISIN1 Gain Setting
CISIN2 Gain Setting
7h
8h
CNTRL2
ISELR
Operation Control 2 (Related to Output Stage)
LED_R Current Setting
9h
0Ah
ISELG
ISELB
LED_G Current Setting
LED_B Current Setting
Adrs
Function
Operation Control 1 (Related to Input Stage)
** Register-address 0Bh-0Fh is an access-inhibit.
** When writing an undefined bit, write 0.
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[AK8456]
Adrs
Name
B7
B6
B5
B4
B3
B2
B1
0h
CNTRL1
Default
NPD
0
SHG0
0
SHG1
0
SHG2
0
--0
VDCO
0
VDCSEL CHN
0
0
 Address 0h B7
NPD
B0
Power-down Setting
Operation
0
Power-down
1
Normal Operation
Both of AFE block and LED driver power-down. LDO for analog block does not power –down.
 Address 0h B6
CISIN0 Sample and Hold Gain
 Address 0h B5
CISIN1 Sample and Hold Gain
 Address 0h B4
CISIN2 Sample and Hold Gain
SHG0/1/2
0
1
Gain at Sample and Hold Block
0dB
6dB
 Address 0h B2
CIS Reference Voltage Source Select
VDCO
CIS Reference Voltage Source
0
1
External
Internal (Output to VDC pin)
 Address 0h B1
CIS Internal Reference Voltage Select
VDCSEL
0
CIS Reference Voltage
1.0V
1
1.1V
 Address 0h B0
CHN
Input Channel Number Select
Channel Number
0
3 Channels
1
1 Channel (Input to CISIN0)
** When writing an undefined bit, write 0.
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[AK8456]
Adrs
Name
B7
B6
B5
1h
2h
Offset 0
Offset 1
－
－
－
－
OFST0
OFST1
3h
Offset 2
Default
－
－
0
0
OFST2
0
 Address 1h B5~B0
CISIN0 Offset Setting
 Address 2h B5~B0
CISIN1 Offset Setting
 Address 3h B5~B0
CISIN2 Offset Setting
OFST0/1/2
01 1111
01 1110
:
00 0001
00 0000
11 1111
:
10 0010
10 0001
10 0000
B4
B3
B2
B1
B0
0
0
0
0
0
Offset Voltage
+369mV
+357.1mV
+11.9mV
0mV
11.9mV
357.1mV
369mV
Inhibit
When set minus value, signal magnitude becomes smaller. When set plus value, signal
magnitude becomes larger.
When 11.9mV setting, image signal decrease 11.9mV.
** When writing an undefined bit, write 0.
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[AK8456]
Adrs
Name
B7
4h
5h
DPGA 0
DPGA 1
DGAIN0
DGAIN1
6h
DPGA 2
Default
DGAIN2
0
0
B6
0
B5
B4
0
0
B3
 Address 4h B7~B0
CISIN0 Digital PGA Gain Setting
 Address 5h B7~B0
CISIN1 Digital PGA Gain Setting
 Address 6h B7~B0
CISIN2 Digital PGA Gain Setting
DGAIN0/1/2
0000 0000
0000 0001
:
1111 1110
1111 1111
B2
B1
B0
0
0
0
Digital PGA Gain
0dB
18dB
Inhibit
Gain( x)  18 x / 254 [dB] x=0~254
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[AK8456]
Adrs
Name
B7
B6
B5
B4
B3
B2
B1
B0
7h
CNTRL2
Default
--0
--0
CASC
0
DEVID
0
--0
DRV
0
--0
FORMAT
0
 Address 7h B5
CASC
Cascade Output Mode Select
Data Output
0
Normal Output
1
Cascade Output
If use cascade output mode, power down mode must be released after setting cascade output
mode select register and device ID select register.
 Address 7h B4
DEVID
0
1
 Address 7h B2
DRV
0
Device ID for Cascade Output Mode
Device ID
0
1
Output Buffer Ability Select
Output Buffer Ability
Normal
1
1/3
If set DRV=1 then output buffer ability of D7~D0 became 1/3 of normal.
 Address 7h B0
FORMAT
0
1
Output Format Select
Output Format
Straight Binary Code
Gray Code
** When writing an undefined bit, write 0.
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[AK8456]
Adrs
Name
B7
B6
8h
9h
Current R
Current G
-----
-----
-----
-----
-----
ISELR
ISELG
Ah
Current B
Default
---
---
---
---
---
ISELB
0
0
0
B5
B4
0
0
 Address 8h B2~B0
LED_R Current Setting
 Address 9h B2~B0
LED_G Current Setting
 Address Ah B2~B0
LED_B Current Setting
ISELR/G/B
000
001
:
110
111
I ( x )  8.4( x  1) [mA]
B3
0
B2
B1
B0
0
0
LED Current
8.4mA
16.8mA
:
58.8mA
67.2mA
x=0~7
** When writing an undefined bit, write 0.
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[AK8456]
11. External Circuit Example
8.2k(note1,4)
ISET
1F(note3,4)
VDC
1F(note2,3,4)
VRP
0.33F(note4,5)
RESETB
1F(note3,4)
AVO
(note6)
LED_R/G/B
AVSS
AVSS
AVSS
AVSS
AVSS
LVSS
OVDD
min. 300
Pull-up(only cascade mode)
D0～7
SDATA
min. 10k
Pull-down or pull-up
AVSS
Fig.25 Reference voltage:D0~ 7,SDOUT,AVO,LED_R/G/B
note1）The resistance precision is ±3 % (including thermal-characteristic)
note2）The capacitance precision is ±50 % (including thermal-characteristic)
note3）Connect them near the pin.
note4）Keep off them from clock line(noise source) and so on.
note5）When not using a power on reset, it is unnecessary, connecting.
note6) Be careful that the voltage of the LED_R/G/B-pin doesn't exceed "LVDD+0.3V" , by
the influence of the overshoot. In case of ,the overshoot is big and the LED wiring
is long, put a capacitor between " the LED_R/G/B terminal " and the grand.
*VDD：OVDD, AVDD, LVDD
*VSS：OVSS, AVSS, LVSS
Note7） Each power pin need this Cap.
*VDD
VDD
0.1F(note7)
10F (note7)
*VSS
Fig.26
Power pins
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[AK8456]
 Connection of Cascade Output Mode
3.3V
3.3V
R
R
R R R
R R R
D7
D6
D5
D4
OVDD
19
20
21
22
23
24
25
29
OVSS
D3
Fig.27
26
17
28
27
19
D0
18
D2
D1
D7
20
21
22
23
24
25
29
D6
D5
D4
OVDD
OVSS
D3
26
27
28
D2
D1
D0
R: min.300
18
17
Cascade mode connection example
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[AK8456]
12. Package
 Dimensions
(36pin QFN 5mm×5mm, Pin Pitch 0.4mm)
Fig.28 Package dimensions
 Marking
1.
2.
Marketing Code
Date Code
:XXX
:Y
:AK8456
Week Number
Control Code
AK8456
XXXY
Note) Marking is preliminary
Fig.29 AK8456 Marking
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[AK8456]
13. Important Notice
IMPORTANT NOTICE
0. Asahi Kasei Microdevices Corporation (“AKM”) reserves the right to make changes to the
information contained in this document without notice. When you consider any use or application
of AKM product stipulated in this document (“Product”), please make inquiries the sales office of
AKM or authorized distributors as to current status of the Products.
1. All information included in this document are provided only to illustrate the operation and
application examples of AKM Products. AKM neither makes warranties or representations with
respect to the accuracy or completeness of the information contained in this document nor grants
any license to any intellectual property rights or any other rights of AKM or any third party with
respect to the information in this document. You are fully responsible for use of such information
contained in this document in your product design or applications. AKM ASSUMES NO
LIABILITY FOR ANY LOSSES INCURRED BY YOU OR THIRD PARTIES ARISING FROM
THE USE OF SUCH INFORMATION IN YOUR PRODUCT DESIGN OR APPLICATIONS.
2. The Product is neither intended nor warranted for use in equipment or systems that require
extraordinarily high levels of quality and/or reliability and/or a malfunction or failure of which
may cause loss of human life, bodily injury, serious property damage or serious public impact,
including but not limited to, equipment used in nuclear facilities, equipment used in the aerospace
industry, medical equipment, equipment used for automobiles, trains, ships and other
transportation, traffic signaling equipment, equipment used to control combustions or explosions,
safety devices, elevators and escalators, devices related to electric power, and equipment used in
finance-related fields. Do not use Product for the above use unless specifically agreed by AKM in
writing.
3. Though AKM works continually to improve the Product’s quality and reliability, you are
responsible for complying with safety standards and for providing adequate designs and safeguards
for your hardware, software and systems which minimize risk and avoid situations in which a
malfunction or failure of the Product could cause loss of human life, bodily injury or damage to
property, including data loss or corruption.
4. Do not use or otherwise make available the Product or related technology or any information
contained in this document for any military purposes, including without limitation, for the design,
development, use, stockpiling or manufacturing of nuclear, chemical, or biological weapons or
missile technology products (mass destruction weapons). When exporting the Products or related
technology or any information contained in this document, you should comply with the applicable
export control laws and regulations and follow the procedures required by such laws and
regulations. The Products and related technology may not be used for or incorporated into any
products or systems whose manufacture, use, or sale is prohibited under any applicable domestic
or foreign laws or regulations.
5. Please contact AKM sales representative for details as to environmental matters such as the RoHS
compatibility of the Product. Please use the Product in compliance with all applicable laws and
regulations that regulate the inclusion or use of controlled substances, including without limitation,
the EU RoHS Directive. AKM assumes no liability for damages or losses occurring as a result of
noncompliance with applicable laws and regulations.
6. Resale of the Product with provisions different from the statement and/or technical features set
forth in this document shall immediately void any warranty granted by AKM for the Product and
shall not create or extend in any manner whatsoever, any liability of AKM.
7. This document may not be reproduced or duplicated, in any form, in whole or in part, without prior
written consent of AKM.
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