AS3691
Datasheet
Datasheet
AS3691
4 Precision 400mA Current Sources for RGB and Single Color Leds
1 General Description
2 Key Features
4 x up to 0.4A constant current outputs
Programmable with external resistors
4 independent PWM inputs
Absolute current accuracy +/-0.5%
’
Automatic Supply Regulation’ to reduce power
dissipation
1)
1)
2)
Patent Pending
4 Application Diagrams
VDD
Csup
100nF
Figure
1 – Application Diagram of AS3691 for Single Color Lighting
Cvdd
100nF
UV
VREG
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AS3691
D1
Ref
Overtemp
Te
Pad VSS
VSS
PWM
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15V is sufficient for most applications as the
AS3691 dose not switch off the LED current
completely
3 Applications
General Lighting
Backlighting
RGB Backlighting for LCD TV/Monitors with
White Color Balancing
Rvdd
UV1
CURR1
UV2
CURR2
UV3
CURR3
UV4
CURR4
Vc
Vc
Vc
Vc
T1
I1
R2
T2
I2
R3
T3
I3
R4
T4
I4
R1
ON1
RFB1
RES1 ON2
RFB2
RES2 ON3
RFB3
RES3 ON4
RFB4
RES4
Ri1
Ri2
Ri3
Ri4
VSS
PWM
Revision 2.3
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VDD
UV
The AS3691 (AS3691A and AS3691B) features four
high precision current sources for lighting of up to
four LED strings (RGB or single color leds). Each
of the four currents sources can be controlled
independently by PWM inputs. The full scale
current value is set by external resistors.
Very wide output voltage current source
voltage compliance
−
Down to 0.41V
2)
−
Up to 15V
Integrated overtemperature protection
Separate sense pads (Rfb1-Rfb4) for easy and
precise PCB Layout
Package
−
DIE
−
QFN24 4x4mm
−
eP-TSSOP
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AS3691
Datasheet
Table of Contents
1
2
3
4
5
General Description ......................................................................................................................................... 1
Key Features.................................................................................................................................................... 1
Applications...................................................................................................................................................... 1
Application Diagrams ....................................................................................................................................... 1
Pinout............................................................................................................................................................... 4
5.2
6
6.1
6.2
6.3
7
8
Pin Descriptions........................................................................................................................................ 4
Absolute Maximum Ratings ...................................................................................................................... 6
Operating Conditions ................................................................................................................................ 6
5.1
Pin Assignments ....................................................................................................................................... 4
Characteristics ................................................................................................................................................. 6
Typical Operation Characteristics .................................................................................................................... 8
Detailed Functional Description ..................................................................................................................... 12
8.1
8.2
8.3
Shunt Regulator...................................................................................................................................... 12
Overtemperature Protection.................................................................................................................... 12
Automatic Supply Regulation.................................................................................................................. 13
9
Application Information .................................................................................................................................. 14
9.1
Design Example...................................................................................................................................... 15
9.1.1
Using Automatic Supply Regulation................................................................................................. 16
9.2
Layout Recommendations ...................................................................................................................... 16
10
10.1
10.2
10.3
11
Package Drawings and Markings ............................................................................................................... 17
QFN 4x4 Package Drawings and Marking .............................................................................................. 17
ePTSSOP Package Drawings and Marking............................................................................................ 19
DIE Delivery............................................................................................................................................ 20
Ordering Information .................................................................................................................................. 21
Revision History
Revision
2.3
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30.10.2007
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Date
Owner
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Description
- Added Trays as delivery option (order code AS3691A-
ZQFT)
Revision 2.3
Electrical Characteristics........................................................................................................................... 7
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