AS3691
4 Precision 400mA Current Sources for
RGB and Single Color LEDs
General Description
The AS3691 (AS3691A and AS3691B) features four high
precision current sinks to drive up to four LED strings. Each of
the current sinks can sustain up to 15V and drive up to 400mA.
Every channel can be controlled independently by PWM inputs.
To ensure best efficiency AS3691 is able to regulate any external
LED power supply (DC-DC converter) to its perfect needs
(patented feedback function).
The full scale current is set by external resistor.
Ordering Information
and
Content Guide
appear at end of
datasheet.
Key Benefits & Features
The benefits and features of the AS3691 4 Precision 400mA
Current Sources for RGB and Single Color LEDs, are listed below:
Figure 1:
Added Value of Using AS3691
Benefits
Features
•
4 × up to 0.4A constant current outputs
•
Programmable with external resistors
•
4 independent PWM inputs
•
Absolute current accuracy ±0.5%
•
’Automatic Supply Regulation’
(1)
to reduce power
dissipation
•
Very wide output voltage current source voltage
compliance
• Down to 0.41V
• Up to 15V
(2)
•
Fully flexible current outputs / no SW effort
•
Perfect color uniformity
•
Unique DC-DC feedback function
•
Maximum number of LEDs per channel
•
On-chip safety features
•
Easy integration due to several package
types including thermal enhanced eP-TSSOP
•
Integrated overtemperature protection
•
Package options:
• QFN24 (4 × 4mm)
• eP-TSSOP
Note(s):
1.
ams
system patent
2. 15V is sufficient for most applications as the AS3691 does not switch off the LED current completely
ams Datasheet
[v2-07] 2016-Jan-21
Page 1
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AS3691 −
Pin Assignments
Pin Number
QFN
Package
Pin Number
eP-TSSOP
Package
Pin Name
Type
Description
Current source CURR4 control; internal pullup
resistor to VREG (can be left open, if CURR4 is
always switched ON)
High … 100% current
Low … 5% current
Automatic supply regulation for CURR4; if not
used, leave open
Digital test input; Leave open or connect to
VSS; internal pulldown to VSS
Automatic supply regulation for CURR3; if not
used, leave open
Current source CURR3 control; internal pullup
resistor to VREG (can be left open, if CURR3 is
always switched ON)
High … 100% current
Low … 5% current
Connect to current set resistor R3
Current source 3 output
Connect to current set resistor R3 directly at
resistor itself
Shunt regulator supply; connect to Rvdd and
Cvdd
Connect to current set resistor R2 directly at
resistor itself
Current source 2 output
Connect to current set resistor R2
Current source CURR2 control; internal pullup
resistor to VREG (can be left open, if CURR2 is
always switched ON)
High … 100% current
Low … 5% current
Automatic supply regulation for CURR2; if not
used, leave open
VSS supply connection
Automatic supply regulation for CURR1; if not
used, leave open
7
16
ON4
DI
8
9
10
17
18
19
UV4
TEST
UV3
AO
AI
AO
11
20
ON3
DI
12
13
14
15
16
17
18
21
22
23
24
1
2
3
RES3
CURR3
RFB3
VREG
RFB2
CURR2
RES2
AI/O
AI/O
AI
S
AI
AI/O
AI/O
19
4
ON2
DI
20
21
22
5
6
7
UV2
VSS
UV1
AO
S
AO
ams Datasheet
[v2-07] 2016-Jan-21
Page 5
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