AK7864A

[AK7864A]
AK7864A
3 channel LED driver with Charge Pump
Device Outline
This product includes the charge pump power supply and the 3 channel LED driver who drives the
LED of the anode common in the constant current. The current to pass for each channel can be
adjusted by the external resistance and the register setting. Also, it has the control pins which turn
on or off the current. It is the suitable for the LED drive for the CIS sensor.
Features
■ Operating Voltage
■ Operating Temperature Range
■ LED Driver Current
3.3V±5%
0 ~ 70 C
RED: 66mA
GREEN: 66mA
BLUE: 66mA
The LED current is adjustable from 22mA to 66mA by the
external resistor. In addition, the LED current can be
reduced to 100%~12.5% by the register.
Allowable maximum Vf of the LED is 4.8V. The 1/16 watt
type is usable to external resistor.

3 chnnel independently ON/OFF
(50% setting is an upper bound when 3ch becoming
turning on at the same time)

Current setting in eight steps
When
the
external
resistance
value
becomes
the
assumption outside, a internal protection circuit restricts the
■
■
■
■
Current Accuracy
LED Current Rise / Fall iime
Charge Pump Pressor Circuit
Package
■ Power Supply
■ Application
MS1336 - E - 00
LED current equal to or less than 150mA (-30%~+45%)
±9.1%(by ideal resistance)
10s (typ.) (10% ~ 90%)
Generate the necessary voltage for the LED (Vf max 4.8V)
16pin QFN 3mm3mm, 0.75mm thickness with radiation
TAB in solderside
VDD 3.135 ~ 3.465V
A light source driver for CIS module of MFP
1
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[AK7864A]
Block Diagram
CPO
CP1
VDD
(3.3V±5%)
CPOUT
LED_R LED_G LED_B
CONT_B
SW
CONT_G
SW
CONT_R
SW
CP
CC
Charge
Pump
(VDD2)
Current
Setting
8 step
Current
Source R
CN
EN
Current
Source G
PDN
Current
Source B
VSS
IREF
R 1%
Circuit Block Description

Charge Pump Circuit
A necessary voltage for LED (Vf 4.8V or less) lighting is generated from the voltage supplied to VDD
pin. Please supply the generated voltage from CPOUT pin to external LED.

LED Driver Part
This product has 3 channel LED driver to drive RGB constant current. Use the ON/ OFF digital
terminal to control the constant current.
The current setting can be set to 8 levels (100%/87.5%/75%/62.5%/50%/37.5%/25%/12.5%) with
CONT_R/G/B and EN combination. The current of 3 channels are same.
It is possible to light 1ch or 3ch simultaneously. Please set the LED current less than 50% by 3ch
simultaneously.
MS1336 - E - 00
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[AK7864A]
Functional Description

Power Down
Set PDN to Low at VDD power on, AK7864A will be in power down state.
In power down state, the current inside AK7864A will be stopped, LED_R/G/B will be High-Z
and CPOUT will be Low.

Circuit reset
PDN is also carrying out the reset of an internal counter, please start supplying VDD to AK7864A by
PDN=Low.
The period of soft start of charge pump is decided at the internal counter.
When soft start does not operate correctly, at the time of starting, incoming current will be large and
the device may break.
MS1336 - E - 00
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[AK7864A]

Current setting method
The method of setting the LED current is as follows.
Latch the logic level of CONT_R, CONT_G, CONT_B at the EN rise. This logic pattern decides the
current level. After the falling edge of the CONT_R, CONT_G, CONT_B, the LED current interlocks
with CONT_R, CONT_G, CONT_B’s on or off.
The current level is set here
EN
Turn RGB on
Not turn on
CONT_R
CONT_G
CONT_B
After first fall, LED is on with EN high period.
The relation between the CONT_R, CONT_G, CONT_B pattern and the current level follows.
CONT_R
CONT_G
CONT_B
0
0
0
100%
0
0
1
87.5%
0
1
0
75%
0
1
1
62.5%
1
0
0
50%
1
0
1
37.5%
1
1
0
25%
1
1
1
12.5%
MS1336 - E - 00
Current setting
4
2012/01
[AK7864A]
Pin Allocation
VSS
LED_G 10
9
VSS 11
LED_R 12
CPOUT 13
VSS 14
AK7864A
Top View
CP 15
CN 16
LED_B
7
CONT_R
6
CONT_G
5
CONT_B
4 EN
3 PDN
2 IREF
1 VDD
MS1336 - E - 00
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[AK7864A]
Pin Functions
No.
1
2
Name
VDD
IREF
3
PDN
I
4
EN
I
5
CONT_B
I
6
CONT_G
I
7
CONT_R
I
8
9
10
11
12
13
LED_B
VSS
LED_G
VSS
LED_R
CPOUT
O
P
O
P
O
O
14
15
VSS
CP
P
I
16
CN
I
radiation pad
IO
P
O
Description
Power supply
LED current setting external resistor connecting pin
(Pulled down by external resistor at power down)
Power down mode terminal
High: power up, Low: power down
LED current enable terminal
High: enable, Low: disable
LED current control input for LED_B
High: ON, Low: OFF
LED current control input for LED_G
High: ON, Low: OFF
LED current control input for LED_R
High: ON, Low: OFF
LED current output pin B (High-Z at Power down)
GND
LED current output pin G (High-Z at Power down)
GND
LED current output pin R (High-Z at Power down)
Charge pump output pin
(Pulled down by internal resistor at power down)
GND
External capacitor connecting pin for charge pump
(Pulled down by internal resistor at power down)
External capacitor connecting pin for charge pump
(Pulled down by internal resistor at power down)
Connect to GND.
I: Input, O: Output, P: Power supply
MS1336 - E - 00
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[AK7864A]
Absolute Maximum Ratings
Voltages are referenced to corresponding ground level. VSS=0V
Item
Symbol
Min.
Max.
Unit
Power supply
VDD
0.3
4.0
V
Input Voltage
VINA
0.3
VDD+0.3
V
Remarks
Storage temperature
Tstg
65
150
C
Operation under a condition exceeding above limits may cause permanent damage to the device.
Normal operation is not guaranteed under the above extreme conditions.
Recommended Operating Conditions
Voltages are referenced to corresponding ground level. VSS=0V
Item
Power supply
Symbol
VDD
Min.
3.135
Ta
0
Storage temperature
Typ.
3.3
Max.
3.465
Unit
V
70
C
Remarks
Electrical Characteristics
1. Digital input DC characteristics
Item
H level input voltage
Symbol
VIH
L level input voltage
VIL
Input leakage current
IL
(VDD=3.135~3.465V, Ta=070C unless otherwise specified)
Pin
Min.
Typ.
Max.
Unit
Remarks
Note1
0.7
V
VDD
Note1
0.3
V
VDD
Note1
2
2
A
(Note 1)PDN, EN, CONT_R, CONT_G, CONT_B
2. Carge pump block analog characteristics
Item
CPOUT Voltage
CPOUT Rise time
CPOUT Fall time
Current Consumption
MS1336 - E - 00
(VDD=3.135~3.465V, Ta=070C unless otherwise specified)
Min.
Typ.
Max.
Unit
Remarks
6.27
6.6
6.93
V
@LED current disable
1
ms
20
ms
4.0
mA
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2012/01
[AK7864A]
3. LED driver block analog characteristics
Item
LED drive current range
The LED protection circuit
activation current
LED current
(R/G/B)
LED current accuracy
(R/G/B)
LED current
LED Vf dependency
LED Vf
Current Consumption
Min.
22
105
(VDD=3.135~3.465V,
Typ.
Max.
66
150
217.5
60
86.0
73.5
60.5
48
35.5
23
10.5
2.5
66
100
87.5
75
62.5
50
37.5
25
12.5
1.1
72
mA
89.0
76.5
64.5
52
39.5
27
14.5
2.5
%
%
%
%
%
%
%
%
%
4.8
1.1
Ta=070C unless otherwise specified)
Unit
Remarks
mA
(note 1)
mA
V
mA
IREF resistor =4.7k±1%
LED pin voltage=2VDD–3.1V
LED pin voltage=2VDD–3.1V
CONT_R/G/B
000
001
010
011
100
101
110
111
Refer to
LED pin voltage=(2VDD–3.1)V
(note 2)
Except LED drive current
(note 1) IREF resistance [k] = 66 ÷ [LED drive current [mA]] × 4.7[k]. [LED drive current] is
possible to be set to 22mA ~ 66mA.
(note 2) In order to keep the normal operation at generation of heat of device, when RGB 3ch
simultaneous lighting, the minimum of Vf has restriction.
Example: (when 3ch simultaneous lighting with drive current 33mA, as for the minimum of
Vf, in 1ch 1.1V and the remaining 2ch are 2.0V) When you use simultaneous lighting,
since we can check for you whether LED Vf combination to use of a drive current value
are possible, please contact us.
(note 3) External load: The total line resistance of CPOUT pin ~ LED anode and LED cathode ~
LED_R/G/G pin must be within 2.
(note 4) 50% setting is an upper bound when all channels turn on at the same time.
MS1336 - E - 00
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[AK7864A]
4. LEDD block, switching characteristics
0.7VDD
EN
0.3VDD
ts
CONTR/G/B
(high setting)
th
0.7VDD
0.7VDD
CONTR/G/B
th
(low setting)
tcl
tcl
0.3VDD
tlon
LED current
90%
10%
tloff
No.
tlon
tloff
ts
th
tcl
(VDD=3.135~3.465V, Ta=070C, unless otherwise specified)
Item
min.
typ.
max.
Unit
Conditions
LED current rise time
10
s
LED current fall time
10
s
Reset valid setup time
1
s
CONTR/G/B
LEDB_EN(0.3AVDD):standard
to
EN(0.3VDD)
Count up setup time
1
s
EN(0.7VDD)
LEDB_EN(0.7AVDD):standard
to
CONTR/G/B
Current set clearing
1
s
CONT_R/G/B:0.7VDD standard
MS1336 - E - 00
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[AK7864A]
5. PDN switching characteristics
Tpd1
3.135V
VDD
Tstup
Tpd2
PDN
EN
(VDD=3.135~3.465V, Ta=070C, unless otherwise specified)
Item
Power down period 1
Power down period 2
Start up time
Symbol
Pin
Tpd1
PDN
Tpd2
PDN
Tstup
EN
Min.
150
150
Typ.
Max.
1
Unit
ns
ns
ms
Conditions
(note 1) Please make PDN and EN Low when you turn on the power supply.
(note 2) LED (CONT_R/G/B control) lighting after max.1ms after EN rise to high.
6. Power Down Characteristic
Item
Supply Current at Power down
MS1336 - E - 00
(VDD=3.135~3.465V, Ta=0~70C, unless otherwise specified)
Min.
Typ.
Max.
Unit.
Remarks
20
A
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2012/01
[AK7864A]
External circuit example
14
VSS
1µF
CONT_R
7
CONT_G
6
CONT_B
5
4
EN
PDN
3
IREF
2
VDD
1
10µF
LED_B
8
AK7864A
Top View
15
CP
16
CN
9
VSS
10
LED_G
1µF
MS1336 - E - 00
11
VSS
12
LED_R
13
CPOUT
4.7k
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2012/01
[AK7864A]
Package
1.
Package dimension
unit [mm]
3.00±0.07
B
1.80
1.50
9
13
8
A
1.50
1.80
3.00±0.07
12
5
16
0.30±0.07
4
1
0.22±0.05
C0.30
0.05 M S A B
0.50
0.05 S
0.12~ 0.18
A部
A
0.00~ 0.05
0.70
0.05MAX
0.75MAX
S
0.17~ 0.27
【 A部詳細図
】
Detail of A
2.
Marking
Marketing code
:7864-A
Date code
:XXXXX
7864-A
XXXXX
MS1336 - E - 00
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[AK7864A]
IMPORTANT NOTICE
 These products and their specifications are subject to change without notice.
When you consider any use or application of these products, please make inquiries the sales
office of Asahi Kasei Microdevices Corporation (AKM) or authorized distributors as to current
status of the products.
 AKM assumes no liability for infringement of any patent, intellectual property, or other rights in the
application or use of any information contained herein.
 Any export of these products, or devices or systems containing them, may require an export
license or other official approval under the law and regulations of the country of export pertaining
to customs and tariffs, currency exchange, or strategic materials.
 AKM products are neither intended nor authorized for use as critical componentsNote1) in any
safety, life support, or other hazard related device or systemNote2), and AKM assumes no
responsibility for such use, except for the use approved with the express written consent by
Representative Director of AKM. As used here:
Note1) A critical component is one whose failure to function or perform may reasonably be
expected to result, whether directly or indirectly, in the loss of the safety or effectiveness of
the device or system containing it, and which must therefore meet very high standards of
performance and reliability.
Note2) A hazard related device or system is one designed or intended for life support or
maintenance of safety or for applications in medicine, aerospace, nuclear energy, or other
fields, in which its failure to function or perform may reasonably be expected to result in loss
of life or in significant injury or damage to person or property.
 It is the responsibility of the buyer or distributor of AKM products, who distributes, disposes of, or
otherwise places the product with a third party, to notify such third party in advance of the above
content and conditions, and the buyer or distributor agrees to assume any and all responsibility
and liability for and hold AKM harmless from any and all claims arising from the use of said
product in the absence of such notification.
MS1336 - E - 00
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2012/01
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