AK7864 [AKM]
3 channel LED driver with Charge Pump; 3通道LED驱动器与电荷泵
| 型号： | AK7864 |
| 厂家： | 
ASAHI KASEI MICROSYSTEMS |
| 描述： | 3 channel LED driver with Charge Pump |
| 文件： | 总12页 (文件大小：212K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
[AK7864]
Device Outline
This product is include the charge pump power supply and include 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 best for the LED drive for the CIS sensor.
Features
■ Operation Voltage
3.3V±5%
■ Operating Temperature Range
■ LED driver current
0 ~ 70℃
RED: 66mA (Adjustment external resister:22 ~ 66mA)
GREEN: 66mA (Same as above, each channel is spec in
absolute value.)
BLUE: 66mA (Same as above, each channel is spec in
absolute value.)
Usable Vf MAX range of the LED is 4.8V. The resistance for
the current regulation is usable in 1/16W -type.
▪ 50% setting is an upper bound when 3ch becoming
turning on at the same time.
▪ 3ch independent ON/OFF.
▪ Current setting in eight steps
When the external resistance value becomes the
assumption outside, it has the protection circuit which
doesn't make the electric current which flows through the
LED equal to or more than 150mA（-30%～+45%）
±9.1%（by ideal resistance）
■ Current Accuracy
■ LED Current rise / fall time
■ Charge Pump pressor circuit
■ Package
10μs (typ.) (10% ~ 90%)
Generate the necessary voltage for the LED （Vf max 4.8V）
16pinQFN 3mm, 0.75mm thickness with radiation TAB in
Solderside
■ Power
VDD 3.135 ~ 3.465V
■ Application
A light source driver for CIS module of MFP
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[AK7864]
Block Diagram
CPO
CP1
VDD
(3.3V±5%)
LED_R
LED_G
LED_B
CPOUT
CONT_B
CONT_G
CONT_R
SW
SW
SW
EN
CP
CN
CP(x2)
Current
3bit
CC
8steps
Current R
PDN
Current G
Current B
IREF
VSS
R
1% accuracy
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 power supply from CPOUT pin to external LED.
□ LED Driver Part
This product generates 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 level with CONT_R/G/B and EN combination.
It is possible to light 1ch LED or 3ch simultaneously. Please set the current less than 50% by 3ch
simultaneously.
-
-
Current setting of 3 channels is same. 3ch ON/OFF independent or at the same time.
Current setting can be set to 8 level with CONT_R/G/B and EN combination.
(100%/87.5%/75%/62.5%/50%/37.5%/25%/12.5%)
-
-
When 100%=60mA, 87.5%=52.5mA、75%=45mA、．．．
When 100%=66mA, 87.5%=57.75mA、75%=49.5mA、．．．
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Current setting method
The method of setting the LED current is as follows.
Latch the pattern of CONT_R, CONT_G, CONT_B at the time of following EN rise to decide the
current value.After the CONT_R, CONT_G, CONT_B signal fall once, the current interlocks with
CONT_R, CONT_G, CONT_B’s on or off.
The level is set here
EN
Turn RGB on
Not turn on
CONT_R
CONT_G
CONT_B
After fall, LED is on
with EN high period.
The relation between the pattern and the current setting value of CONT_R, CONT_G, CONT_B at
the time of the EN rise as follows.
CONT_R CONT_G CONT_B Current setting
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
100%
87.5%
75%
62.5%
50%
37.5%
25%
12.5%
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[AK7864]
Pin Allocation
CPOUT 13
VSS 14
CP 15
8
7
6
5
LED_B
CONT_R
AK7864
Top View
CONT_G
CONT_B
CN 16
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Pin Functions
No.
Name
VDD
IO
P
O
Description
1
2
power supply
IREF
PDN
EN
LED current setting external resister pin
（Use the external resistance Pull Down by power down）
Power down mode terminal
Hi: power up, Lo: power down
LED current enable terminal
Hi:enable, Lo:disable
3
4
5
6
7
I
I
I
I
I
CONT_
B
CONT_
G
CONT_
R
LED control input B
LED control input G
LED control input R
8
9
LED_B
VSS
O
P
LED output pin B （Hi-z@PD）
GND
10
11
12
13
LED_G
VSS
LED_R
CPOUT
O
P
O
O
LED output pin G （Hi-z@PD）
GND
LED output pin R （Hi-z@PD）
Charge pump power supply out put pin
（Use the internal resistance Pull Down by power down）
GND
Charge pump connect with cap positive terminal
（Use the internal resistance Pull Down by power down）
Charge pump connect with cap negative terminal
（Use the internal resistance Pull Down by power down.）
14
15
VSS
CP
P
I
16
CN
I
radiation pad
Connect it with GND.
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[AK7864]
Absolute Maximum Ratings
Voltages are referenced to corresponding ground level. VSS=0V
Item
Power supply
Symbol
VDD
Min.
−0.3
−0.3
−65
Max.
4.0
Unit
V
Remarks
Input Voltage
VINA
Tstg
VDD+0.3
150
V
Storage temperature
°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
Typ.
3.3
Max.
3.465
Unit
V
Remarks
Storage temperature
Ta
0
70
°C
When powered-up, Please set PDN to Lo, then set PDN to Hi. Release from reset + PD.
Electrical Characteristics
1. Digital input DC characteristics
(VDD=3.135~3.465V, Ta=0∼70°C unless otherwise specified)
Item
level input
voltage
Symbol
VIH
Pin
Note
1
Min.
0.7×
VDD
Typ.
Max.
Unit.
V
Remarks
H
L
level input
VIL
IL
Note
1
Note
1
0.3×
VDD
2
V
voltage
Input
current
leakage
-2
μA
（Note 1） PDN, EN, CONT_R,G,B
2. CP block, Analog characteristics
(VDD=3.135~3.465V, Ta=0∼70°C unless otherwise specified)
Item
CPOUT Voltage
Min.
6.27
Typ.
6.6
Max.
6.93
1
Unit
V
Remarks
@LED current disable
CPOUT Rise time
CPOUT Fall time
Current Consumption
msec
msec
mA
20
4.0
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3. LEDD block, Analog characteristics
(VDD=3.135~3.465V ,Ta=0∼70°C unless otherwise specified)
Item
LED drive current range
The LED protection circuit
activation current
LED current
Min.
22
Typ.
150
66
Max.
66
Unit
mA
mA
Remarks
（note 1）
105
217.5
IREF resister =4.7 kΩ±1%
60
72
mA
LED pin voltage =(2*VDD – 3.1)V
(R/G/B)
LED pin voltage =(2*VDD – 3.1)V
LED current accuracy
(R/G/B)
100
87.5
75
62.5
50
37.5
25
12.5
%
%
%
%
%
%
%
%
%
000
001
010
011
100
101
110
111
86.0
73.5
60.5
48
35.5
23
89.0
76.5
64.5
52
39.5
27
10.5
-2.5
14.5
2.5
LED pin voltage =(2*VDD – 3.1)V
reference
LED current LED pin voltage
dependence
LED Vf
1.1
4.8
V
(note 2)
Current Consumption
1.1
mA
Except LED drive current
（note 1） IREF resistance value(kΩ) ＝ 66 ÷ [LED set value (mA)] × 4.7(kΩ) , also [LED set value]
is possible to set with 22mA ~ 66mA.
(note 2) Set a lower limit value 1.1V to be only 1ch in 3ch, and use the other 2ch by 2.0V or more
with LED_Vf.
(note 3) External load: The total line resistance value of CPOUT pin ~ LED anode and LED
cathode ~ LED_X pin within 2Ω.
(note 4) 50% setting is an upper bound when 3ch becoming turning on at the same time.
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4. LEDD block, Switching characteristics
0.7VDD
EN
0.3VDD
ts
th
CONTR/G/B
(high setting)
0.7VDD
0.7VDD
tcl
th
tcl
CONTR/G/B
(low setting)
0.3VDD
tlon
90%
LED current
10%
tloff
(VDD=3.135~3.465V ,Ta=0∼70°C, unless otherwise specified)
No.
tlon
tloff
ts
Item
min.
typ.
10
10
max.
Unit
μsec
μsec
μsec
Conditions
LED current rise time
LED current fall time
Reset valid setup time
LEDB_EN(0.7AVDD):base
position
Count up setup time
LEDB_EN(0.3AVDD):base
position
1
1
1
CONTR/G/B to
EN(0.7VDD)
th
μsec
μsec
EN(0.3VDD) to
CONTR/G/B
tcl
Current set clearing
CONT_x:0.7VDD: base position
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[AK7864]
5. PDN Switching characteristics
pd
T
1
3.135V
Power
Tstup
Tpd2
PDN
E
(VDD=3.135~3.465V ,Ta=0∼70°C, unless otherwise specified)
Item
Symbol
Tpd1
Pin
PDN
Min.
150
150
Typ. Max. Unit
Conditions
Power down period 1
Power down period 2
Start up time
ns
ns
Tpd2
PDN
EN
Tstup
1
ms
( note 1) Please make PDN and EN Lo when you turn on the power supply.
( note 2) LED's lighting after max.1msec after standing up of PDN.
6. Power Down Characteristic
(VDD=3.135~3.465V ,Ta=0∼70°C, unless otherwise specified)
Item
Min.
Typ.
Max.
20
Unit.
µA
Remarks
Power Down Current
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[AK7864]
External circuit example
LED_B
8
13
CPOUT
1µF
CONT_R
14
VSS
7
AK7864
CONT_G
Top View
15
6
1µF
CP
CONT_B
5
16
CN
10µF
4.7kΩ
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[AK7864]
Package
1 Package dimension unit [mm]
3.00±0.07
B
1.80
1.50
9
12
13
8
A
5
16
4
1
C0.30
0.22±0.05
S A B
0.05 M
S
A部
S
0.05
0.50
0.17～0.27
【A部詳細図】
2 Marking
１．Marketing code
：7864
２．Date code
：XXXXX
7864
XXXXX
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[AK7864]
IMPORTANT NOTICE
z 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.
z AKM assumes no liability for infringement of any patent, intellectual property, or other rights in the
application or use of any information contained herein.
z 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.
z 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.
z 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.
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