ams AS3691B-ZQFP 4 precision 400ma current sources for rgb and single color led Datasheet

austriamicrosystems AG
is now
ams AG
The technical content of this austriamicrosystems datasheet is still valid.
Contact information:
Headquarters:
ams AG
Tobelbaderstrasse 30
8141 Unterpremstaetten, Austria
Tel: +43 (0) 3136 500 0
e-Mail: [email protected]
Please visit our website at www.ams.com
AS3691
Datasheet
Datasheet
AS3691
4 Precision 400mA Current Sources for RGB and Single Color Leds
1 General Description
2)
15V is sufficient for most applications as the
AS3691 dose not switch off the LED current
completely
am
lc s
on A
te G
nt
st
il
Patent Pending
lv
ƒ
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
dissipation1)
1)
al
id
ƒ
ƒ
2 Key Features
ƒ
ƒ
ƒ
ƒ
ƒ
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
ƒ
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.
3 Applications
General Lighting
Backlighting
RGB Backlighting for LCD TV/Monitors with
White Color Balancing
ƒ
ƒ
ƒ
4 Application Diagrams
Figure 1 – Application Diagram of AS3691 for Single Color Lighting
VDD
Csup
100nF
VDD
Rvdd
Cvdd
100nF
ca
UV
VREG
CURR1
ni
UV1
AS3691
UV2
CURR2
Vc
UV3
CURR3
Vc
UV4
UV
CURR4
Vc
Vc
ch
D1
Ref
T1
I1
Te
Overtemp
Pad VSS
T2
I2
R1
ON1
RFB1
T3
R2
RES1 ON2
RFB2
T4
I3
R3
RES2 ON3
Ri1
Ri2
RFB3
I4
R4
RES3 ON4
Ri3
RFB4
RES4
Ri4
VSS
VSS
PWM
PWM
www.austriamicrosystems.com (ptr)
Revision 2.3
1 - 22
AS3691
Datasheet
Figure 2 – Application Diagram of AS3691 for RGB Lighting
VDDG
VDDG
VDDB
VDDB
VDDR
VDDR
Rvdd
al
id
Cvdd
100nF
UVG
UVG
UVB
UVB
UVR
UVR
CURR1
AS3691
UV3
CURR2
Vc
Ref
Vc
T1
Pad
T2
PWMB
Vc
VSS
ON1
RFB1
R2
RES1 ON2
RFB2
T4
I3
R3
RES2 ON3
Ri2
RFB3
I4
R4
RES3 ON4
Ri3
RFB4
RES4
Ri4
VSS
PWMG
PWMB
PWMR
Te
ch
ni
ca
PWMR
CURR4
T3
I2
R1
Ri1
PWMG
UV4
Vc
I1
Overtemp
VSS
CURR3
am
lc s
on A
te G
nt
st
il
D1
UV2
lv
UV1
VREG
www.austriamicrosystems.com (ptr)
Revision 2.3
2 - 22
AS3691
Datasheet
Table of Contents
1
General Description ......................................................................................................................................... 1
2
Key Features.................................................................................................................................................... 1
3
Applications...................................................................................................................................................... 1
4
Application Diagrams ....................................................................................................................................... 1
5
Pinout............................................................................................................................................................... 4
Pin Assignments ....................................................................................................................................... 4
5.2
Pin Descriptions........................................................................................................................................ 4
6
al
id
5.1
Characteristics ................................................................................................................................................. 6
Absolute Maximum Ratings ...................................................................................................................... 6
6.2
Operating Conditions ................................................................................................................................ 6
6.3
Electrical Characteristics........................................................................................................................... 7
7
lv
6.1
Typical Operation Characteristics .................................................................................................................... 8
8
Detailed Functional Description ..................................................................................................................... 12
Shunt Regulator...................................................................................................................................... 12
8.2
Overtemperature Protection.................................................................................................................... 12
8.3
Automatic Supply Regulation.................................................................................................................. 13
9
am
lc s
on A
te G
nt
st
il
8.1
Application Information .................................................................................................................................. 14
9.1
Design Example...................................................................................................................................... 15
9.1.1
Using Automatic Supply Regulation................................................................................................. 16
9.2
Layout Recommendations ...................................................................................................................... 16
10
Package Drawings and Markings ............................................................................................................... 17
10.1
QFN 4x4 Package Drawings and Marking .............................................................................................. 17
10.2
ePTSSOP Package Drawings and Marking............................................................................................ 19
10.3
DIE Delivery............................................................................................................................................ 20
11
Ordering Information .................................................................................................................................. 21
ca
Revision History
Revision
Owner
Description
30.10.2007
ptr
- Added Trays as delivery option (order code AS3691AZQFT)
Te
ch
ni
2.3
Date
www.austriamicrosystems.com (ptr)
Revision 2.3
3 - 22
AS3691
Datasheet
5 Pinout
5.1 Pin Assignments
Figure 3 – Pin Usage
UV1
CURR1
AS3691
UV2
CURR2
Vc
UV3
CURR3
Vc
UV4
CURR4
al
id
VREG
Vc
Vc
D1
T1
I1
Overtemp
R1
T3
I2
R2
T4
I3
R3
I4
R4
am
lc s
on A
te G
nt
st
il
Pad
T2
lv
Ref
VSS
ON1
RES1 ON2
RFB1
RES2 ON3
RFB2
RFB3
RES3 ON4
RFB4
RES4
5.2 Pin Descriptions
Table 1 – Pin Type Descriptions
Pin Type
AI/O
Description
Analog Pin
Analog Input Pin
AO
Analog Output Pin
DI
Digital Input
S
Supply Pin
ca
AI
Table 2 – Pin Descriptions
Pin Number
QFN
Package
Pin Number
ePTSSOP
Package
Pin Name
1
10
Description
CURR1
AI/O
Current Source 1 Output
11
RFB1
AI
Connect to current set resistor R1 directly at
resistor itself
3
12
nc
nc
Leave open
4
13
RFB4
AI
Connect to current set resistor R4 directly at
resistor itself
5
14
CURR4
AI/O
Current Source 4 Output
6
15
RES4
AI/O
Connect to current set resistor R4
Te
ch
2
ni
Type
www.austriamicrosystems.com (ptr)
Revision 2.3
4 - 22
AS3691
Datasheet
Pin Number
QFN
Package
Pin Number
ePTSSOP
Package
Pin Name
Type
Description
16
ON4
DI
8
17
UV4
AO
Automatic supply regulation for CURR4; if not
used, leave open
9
18
TEST
AI
Digital Test input; Leave open or connect to
VSS; internal pulldown to VSS
10
19
UV3
AO
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
lv
al
id
7
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
20
ON3
DI
12
21
RES3
AI/O
Connect to current set resistor R3
13
22
CURR3
AI/O
Current Source 3 Output
14
23
RFB3
AI
Connect to current set resistor R3 directly at
resistor itself
15
24
VREG
S
Shunt regulator supply; connect to Rvdd and
Cvdd
16
1
RFB2
AI
Connect to current set resistor R2 directly at
resistor itself
2
CURR2
AI/O
Current Source 2 Output
3
RES2
AI/O
Connect to current set resistor R2
am
lc s
on A
te G
nt
st
il
11
17
18
19
20
DI
5
UV2
AO
Automatic supply regulation for CURR2; if not
used, leave open
6
VSS
S
7
ch
8
VSS Supply connection
AO
Automatic supply regulation for CURR1; if not
used, leave open
ON1
DI
Current source CURR1 control; internal pullup
resistor to VREG (can be left open, if CURR1 is
always switched on)
High … 100% Current
Low … 5% Current
UV1
ni
22
23
ON2
ca
21
4
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
9
RES1
AI/O
Pad
Pad
VSS
S
Connect to current set resistor R1
VSS Supply connection; add as many vias to
ground plane as possible
Te
24
www.austriamicrosystems.com (ptr)
Revision 2.3
5 - 22
AS3691
Datasheet
6 Characteristics
6.1 Absolute Maximum Ratings
Stresses beyond those listed in Table 1 may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated in Section 5
Electrical Characteristics is not implied.
Table 3 – Absolute Maximum Ratings
Note
al
id
Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Symbol
Parameter
Min
Max
Unit
VDDMAX
Supply for LEDs
-0.3
>17
V
See notes1
VINVREG
VREG Supply voltage
-0.3
7.0
V
Applicable for pin VREG
V
Applicable for 5V pins2
V
Applicable for CURR1, CURR2,
CURR3 and CURR4
5V Pins
-0.3
VIN15V
15V Pins
-0.3
17
IIN
Input Pin Current
-25
+25
mA At 25ºC, Norm: Jedec 17
TSTRG
Storage Temperature Range
-55
125
°C
Humidity
5
85
%
Non condensing
VESD
Electrostatic Discharge
-2000
2000
V
Norm: MIL 883 E Method 3015
PT
Total Power Dissipation
2.0
W
At 50ºC, no airflow for QFN24 on
3
two layer FR4-Cu PCB
PDERATE
PT Derating Factor
23
TBODY
Body Temperature during
Soldering
260
am
lc s
on A
te G
nt
st
il
Notes:
1.
2.
3.
lv
VIN5V
VREG+
0.3V
mW/
See notes3
°C
°C
according to IPC/JEDEC J-STD020C
As the AS3691 is not directly connected to this supply. Only the parameters VINVREG, VIN5V and
VIN15V have to be guaranteed by the application
All pins except CURR1, CURR2, CURR3 and CURR4
Depending on actual PCB layout and especially number of vias below the exposed pad – see layout
recommendations; can be improved e.g. with Al-PCB or airflow
ca
6.2 Operating Conditions
Symbol
Parameter
Te
VDDTOL Main Supply Voltage Tolerance
VREGINT
Min
Typ
Main Supply
ch
VDD
ni
Table 4 – Operating Conditions
Supply (shunt regulated by
AS3691)
VREGEXT
IVREG
Supply Current
TAMB
Ambient Temperature
www.austriamicrosystems.com (ptr)
-20
Max
Unit
Note
Not
Limited
V
Supply is not directly connected to
the AS3691 – see section ‘Shunt
Regulator’
+20
%
Applies only for supply VREG is
connected via Rvdd
5.0
5.2
5.4
V
If internally (shunt-)regulated by
D1
4.5
4.75
5.0
V
If externally supplied
-20
25
Revision 2.3
2.5
Excluding current through shunt
mA regulator (D1) – see section
‘Shunt Regulator’
85
°C
6 - 22
AS3691
Datasheet
6.3 Electrical Characteristics
Table 5 – Analog Electrical Characteristics
Current Source CURR1 to
CURR4 Voltage Compliance
VCURR
ICURR
Current Source Range
ICURR,
Min
Typ
Max
Unit
0.9
15.0
V
0.41
15.0
V
at 100mA
10
400(1)
mA
-0.5
+0.5
%
@25C TJUNCTION, excluding
variation of external resistors;
V(CURRx) <= 4.0V
%
(2)
-20°C to +100°C TJUNCTION,
-20°C to +85°C TAMB, excluding
variation of external resistors;
V(CURRx) <= 4.0V
Current Source Tolerance
TOL
Note
at 400mA; total power dissipation
limit PT must not be exceeded
-1.5
+1.5
ONx = high
ICURRx = 250mV / Rix (x=1...4)
al
id
Parameter
lv
Symbol
Automatic Supply Regulation
compare voltage
1.0
V
See section ‘Automatic Supply
Regulation’
VC,GAIN
Automatic Supply Regulation
gain
2.0
mA/V
Voltage to current ratio; output
current range typ 0 to 200uA
I1-4
Parallel Current
TOVTEMP
Overtemperature Limit
am
lc s
on A
te G
nt
st
il
VC
Notes:
1.
2.
1.0
mA V(CURRx) <= 15V
0.1
mA V(CURRx) <= 5.0V
°C
140
Maximum junction temperature
To obtain higher currents connect more than one current source in parallel
Accuracy at +100°C guaranteed by design and verified by laboratory characterization
Table 6 – Digital Input pins characteristics for pins ON1, ON2, ON3 and ON4
Parameter
Min
VIH
High Level Input voltage
VIL
Low Level Input voltage
Unit
2.3
VREG
V
0.0
0.9
V
Pullup resistor
ni
RPU
Input Frequency Range
Typ
kΩ
70
0
20
Note
Internal pullup resistor R1 to R4 to
VREG
This defines the actual input
frequency seen on the input ON1
kHz to ON4; the basic frequency to
generate the PWM signal is not
limited by this parameter
Te
ch
fON
Max
ca
Symbol
www.austriamicrosystems.com (ptr)
Revision 2.3
7 - 22
AS3691
Datasheet
7 Typical Operation Characteristics
Figure 4 – Output Current versus Voltage on Current Source – High Current Range
0,45
0,4
0,3
0,25
al
id
I(CURR1) [A]
0,35
0,2
0,15
0,1
lv
0,05
0
0
5
10
15
am
lc s
on A
te G
nt
st
il
VCURR1 [V]
Figure 5 – Output Current versus Voltage on Current Source – Low Current Range
12
I(CURR1) [mA]
10
8
6
4
2
0
0
2
4
6
8
10
12
14
ca
VCURR1 [V]
ni
Figure 6 – Internal voltage reference versus Temperature, V(CURR1) = 2.0V, Ri1=250Ω
253
V(RES1) [mV]
Te
ch
252
251
250
249
ICURR1 =
248
V ( RES 1)
Ri1
247
0
20
40
60
80
100
120
140
Temperature [C]
www.austriamicrosystems.com (ptr)
Revision 2.3
8 - 22
AS3691
Datasheet
Figure 7 – Output Currnent versus Temperature, V(CURR1) = 2.0V, Ri1 = 2.5Ω (Note: temperature coefficient of Ri1 = -200ppm/°C)
al
id
101
100
99
98
0
10
20
30
40
60
70
am
lc s
on A
te G
nt
st
il
Temperature [C]
50
lv
I(CURR1) [mA]
102
Te
ch
ni
ca
Figure 8 – Cross coupling of pwm on CURR1 to CURR2; I(CURR1) = 100mA to 4mA, I(CURR2) = 100mA; AS3691A
www.austriamicrosystems.com (ptr)
Revision 2.3
9 - 22
AS3691
Datasheet
am
lc s
on A
te G
nt
st
il
lv
al
id
Figure 9 – PWM performance of Current Source CURR1, I(CURR1) changed between 400mA (ON1=1) and 20mA (ON1=0); AS3691A
Figure 10 – Shunt Regulator Voltage VREG versus supply VDD with Rfb=1kΩ
6
4
ca
3
2
ni
VREG [V]
5
1
ch
0
5
10
15
20
25
30
35
40
VDD [V]
Te
0
www.austriamicrosystems.com (ptr)
Revision 2.3
10 - 22
AS3691
Datasheet
am
lc s
on A
te G
nt
st
il
lv
al
id
Figure 11 – Automatic Supply Regulation dynamic performance using DCDC converter in regulation loop (as in section 7.3)
R1 = 47kΩ, R2 = 10kΩ, R3 = 5kΩ, R4 = 500Ω, C1 = 1uF, I(CURR1) = 400mA/20mA (Ri1=0.625Ω)
3 OSRAM Golden Dragon in series as load between CURR1 and VDD
Input signal on pin ON1: PWM signal with f=10kHz, 80% duty cycle
Figure 12 – Parallel Current I1 to I4 (for measurement of I1 remove current set resistor R1)
0,7
0,5
0,4
ca
I(CURR1) [mA]
0,6
0,3
ni
0,2
0,1
0
5
10
15
VCURR1 [V]
Te
ch
0
www.austriamicrosystems.com (ptr)
Revision 2.3
11 - 22
AS3691
Datasheet
8 Detailed Functional Description
The AS3691 includes four high precision current sources (sinks). Each current source is set by an external
resistor. For internal power supply an internal shunt regulator is used. Optionally an additional 5V device can be
supplied as well with this shunt regulator.
The current sources are individually controlled by four ON inputs. If the inputs ON are high or left open, then the
current is set as follows:
250mV
Ri1−4
al
id
ICURR1−4 =
Setting the input ON to low the current is
10.0mV
Ri1− 4
for part numbers starting
with AS3691A
lv
ICURR1− 4 =
The current is not zero to avoid high voltage jumps on the LEDs and supplies and therefore reduce EMI.
0.0mV
+ I1− 4 = I1− 4
Ri1− 4
for part numbers starting with AS3691B; I1-4 is the parallel current
(see above Figure 11)
am
lc s
on A
te G
nt
st
il
ICURR1− 4 =
8.1 Shunt Regulator
The supply of the AS3691 is generated from the high voltage supply. To obtain a 5V regulated supply, a series
resistor Rvdd is used together with an internal zener diode (shunt regulator principle). An external capacitor
Cvdd is used to filter the supply on the pin VREG.
The external resistor Rvdd has to be choosen according to the following formula:
Rvdd =
VDDMIN − VVREGINTMAX
IVREGMAX
VDDMIN is the minimum voltage of the
supply, where Rvdd is connected
This ensures enough supply current (IVREGMAX) for the AS3691 under minimum supply voltage VDDMIN.
ca
If a stable 5V supply within the operating conditions limits of VREGEXT is already existing in the system it is
possible to supply the AS3691 directly. In this case remove the resistor Rvdd and connected this supply directly
to VREG.
ni
8.2 Overtemperature Protection
Te
ch
If the junction temperature inside the AS3691 rises above TOVTEMP, the current sources are switched off.
www.austriamicrosystems.com (ptr)
Revision 2.3
12 - 22
AS3691
Datasheet
8.3 Automatic Supply Regulation
The purpose of the automatic supply regulation is to minimize the voltage supply to reduce the voltage across the
current sources of the AS3691 (CURR1-CURR4 to VSS) and therefore reduce the power dissipation of the
AS3691 and the complete system. The AS3691 automatically controls the minimum required supply voltage for
the different led strings to support very power efficient systems for lighting using the following circuit (any off-theshelf dcdc converter or ldo with adjustable output voltage can be used):
VDDx
From main
supply
R1
Voltage Feedback Vfb
input for DCDC
R2
R3
R4
Csup
100nF
UVx
C1
UV1
CURR1
UV2
CURR2
am
lc s
on A
te G
nt
st
il
Feedback resistor divider
(part of DCDC converter circuit)
lv
DCDC Converter
for VDD
al
id
Figure 13 – Automatic Supply Regulation Circuit
Vc
Vc
AS3691
The function of this circuit is as follows:
All channels, which are connected to the supply VDDx should have their respective UV pin connected together to
UVx (see above Figure and Section ‘Application Schematic’). If any of these current sources has a too low
voltage, it gradually pulls the wire UVx low. (The analog gain between the current source CURRx and output UVx
is defined by the parameter VC,GAIN.)
Therefore the feedback pin Vfb of the dcdc converter is pulled low and the dcdc converter compensates this by
increasing the voltage on VDDx to obtain the same feedback voltage as before.
To stabilize this regulation loop, the low pass filter build by C1 and R4 is used (this should be the dominant pole
for the regulation loop).
The minimum output voltage VDDxmin can be set accurately by the resistors R1 and R2. The maximum output
voltage VDDxmax is set by R1, R2, R3 and R4 (Vref is the internal voltage reference of the DCDC converter;
usually Vref = Vfb):
R1 + R2
R2
VDDxMAX = Vref
R1 + R2 ( R3 + R4 )
R2 ( R3 + R4 )
ni
ca
VDDxMIN = Vref
Te
ch
Therefore even if a led string is broken (then UVx is forced to 0V) or some leds are shorted, the supply always
stays within the limits VDDxMIN and VDDxMAX.
www.austriamicrosystems.com (ptr)
Revision 2.3
13 - 22
AS3691
Datasheet
9 Application Information
Typical Application Schematic
For RGB leds (and a white color balancing circuit) use the following application schematic including automatic
supply regulation (feedback paths UVR, UVG, UVB):
Main
supply
DCDC Converter
for VDDR
VDDR
Voltage Feedback
input for DCDC
UVR
al
id
Figure 14 – Typical AS3691 System for RGB (back-)lighting; several AS3691 can be cascaded
DCDC Converter
for VDDG
VDDG
Voltage Feedback
input for DCDC
UVG
lv
Feedback resistor divider
(part of DCDC converter circuit)
am
lc s
on A
te G
nt
st
il
Feedback resistor divider
(part of DCDC converter circuit)
DCDC Converter
for VDDB
VDDB
Voltage Feedback
input for DCDC
UVB
Feedback resistor divider
(part of DCDC converter circuit)
VDDG
VDDB
VDDR
...
...
UVG
UVB
UVR
D1
Overtemp
Vc
Vc
Vc
Vc
Vc
...
D1
Overtemp
Overtemp
AS3691
AS3691
VSS
ch
Te
www.austriamicrosystems.com (ptr)
Vc
D1
ni
AS3691
Vc
ca
Vc
...
PWMG
PWMB
PWMR
5V Supply
5V powered
system
(optional)
PWMG
PWMB
PWMR
Revision 2.3
14 - 22
AS3691
Datasheet
A typical AS3691 for single color leds can be done as follows using automatic supply regulation (feedback path
UV):
Figure 15 – Typical AS3691 system for single color leds and supply regulation loop; serveral AS3691 can be cascaded
VDD
DCDC Converter
for VDD
...
...
Voltage Feedback
input for DCDC
al
id
Main
supply
Csup
100nF
UV
...
PWM
(optional)
Vc
Vc
D1
Overtemp
...
Overtemp
AS3691
AS3691
am
lc s
on A
te G
nt
st
il
5V powered
system
(optional)
Vc
lv
Vc
D1
VSS
PWM
Note: Csup (100nF) is only required, if there are long wires (>0.3m) between the DCDC converter and the
AS3691. The wire length between the Csup capacitor and the CURRx pin on AS3691 should not exceed 0.3m.
If this cannot be guaranteed, add additional capacitors of 100nF to the pins CURRx.
9.1 Design Example
Assume a single color leds application (4 times 3 leds in series, each 100mA with Uf ranging from Ufmin=3.2V to
Ufmax = 3.8V) with a fixed supply. First choose the external current set resistor with the following formula:
Ri1− 4 =
250mV
ICURR1− 4
So for a current of 100mA, use a resistor of 2.5Ω; 1/8W rated resistors are suitable (even up to 400mA).
ca
Then calculate the required voltage of the power supply. The minimum voltage on the current sink for
guaranteed operation is 0.41V (VCURR @100mA) and the maximum forward voltage of the LEDs is assumed to
be Ufmax = 3.8V. Therefore 3*3.8V + 0.41V = 11.81V.
ni
As this is the required minimum voltage of the power supply, add all the tolerances on top. Assumed +/-10%
supply tolerance results in a power supply with nominal 13V (to have at least 11.81V in worst case).
Using the following formula to calculate the external shunt resistor
VDDMIN − VREGINTMAX VDDMIN − 5.4V
=
IVREGMAX
2.5mA
ch
Rvdd =
VDDMIN is the minimum voltage of the
power supply, where Rvdd is connected
Te
obtains 2564Ω. The nearest lower(!) available value is 2.4kΩ. For Cvdd use
Cvdd = 100nF
Csup (100nF) is only required, if there are long connections between the DCDC converter and the AS3691
(>0.3m). The wire length between the Csup capacitor and the CURRx pin on AS3691 should not exceed 0.3m. If
this cannot be guaranteed, add additional capacitors of 100nF to the pins CURRx.
www.austriamicrosystems.com (ptr)
Revision 2.3
15 - 22
AS3691
Datasheet
Then calculate the maximum power dissipation inside the AS3691. The worst case is maximum voltage supply
(13V + 10%) together with LEDs with minimum forward voltage Ufmin :
For these conditions the maximum voltage on any current source (CURR1 to CURR4) is
VCURRMAX = (1 + VDDTOL ) VDD − n Uf min
Not using automatic supply regulation
In our example 14.3V – 9.6V = 4.7V. The maximum power dissipation inside the AS3691 is now (assuming 4
identical strings)
al
id
PMAX = 4 VCURRMAX ICURR
In our example 1.88W. As
TMAX =
PT − P MAX
+ 50 o C
PDERATE
For PT and PDERATE see Absolute
Maximum Ratings
am
lc s
on A
te G
nt
st
il
lv
the system can be operated safely up to an ambient temperature of 55°C assuming worst case power supplies
and worst case leds. Please note: If the internal junction temperature of the AS3691 rises too high, the AS3691
will switch off the current sources for protection (it will never damage the AS3691).
9.1.1 Using Automatic Supply Regulation
For the identical system using the automatic supply regulation, the supply is regulated to minimize the power
dissipation of the system. Therefore the tolerance of the VDD supply and also the variation in forward voltages of
the LEDs can be ignored (only the difference in one lot of leds is still important, as the four strings are connected
in parallel to the power supply). Assume a difference of ΔUf = 0.2V of forward voltage of the leds in one lot, then
calculate the maximum voltage on the current source of the AS3691 (CURR1 to CURR4) with
Using automatic supply regulation
ΔUf variation of LED forward voltage
in one lot (for one application)
VC is internal set voltage (1.0V)
VCURRMAX = n ΔU f + VC
to be 1.6V. Using the identical formulas as above, PMAX now is 0.64W and TMAX is 110°C.
ca
Therefore using automatic supply regulation, the ambient temperature can be up to 110°C under identical
conditions.
9.2 Layout Recommendations
ni
See austriamicrosystems ‘AN3691_TECH_Module Description’ as a layout example for the AS3691.
Te
ch
Layout Checklist
1. Use the bottom layer as ground plane and minimize the number and the length of connections within
this layer
2. Do as many vias as possible on the exposed pad (for thermal performance) to the ground plane
3. Connect RFBx and RESx together at the current set resistor Rix (see above recommended layout)
4. The ground connections of the current set resistors should be as close to the AS3691 as possible
5. The ground connection of the capacitor Cvdd should be as close as possible to the AS3691
6. Minimize Area build by ‘Csup VSS connection – Csup Supply Connection – LEDs – CURRx – Csup
VSS connection’ (to minimize inductance in this path)
www.austriamicrosystems.com (ptr)
Revision 2.3
16 - 22
AS3691
Datasheet
10 Package Drawings and Markings
10.1 QFN 4x4 Package Drawings and Marking
ch
ni
ca
am
lc s
on A
te G
nt
st
il
lv
al
id
Figure 16 – QFN 24 – 4x4mm
Te
Marking:
Line 1: austriamicrosystems Logo
Line 2: AYWWIZZ
A = Pb-Free Identifier
Y = Year
WW = Week
I = Plant Identifier
ZZ = Letters of Free Choice
Line 3: AS3691, AS3691A or AS3691B
www.austriamicrosystems.com (ptr)
Revision 2.3
17 - 22
AS3691
Datasheet
Te
ch
ni
ca
am
lc s
on A
te G
nt
st
il
lv
al
id
Figure 17 – QFN 24 – 4x4mm Detail Dimensions
www.austriamicrosystems.com (ptr)
Revision 2.3
18 - 22
AS3691
Datasheet
10.2 ePTSSOP Package Drawings and Marking
Te
ch
ni
ca
am
lc s
on A
te G
nt
st
il
lv
al
id
Figure 18 – ePTSSOP Package Drawing
www.austriamicrosystems.com (ptr)
Revision 2.3
19 - 22
AS3691
Datasheet
Marking:
Line 1: austriamicrosystems Logo
Line 2: AYWWIZZ
A = Pb-Free Identifier
Y = Year
WW = Week
I = Plant Identifier
ZZ = Letters of Free Choice
Line 3: AS3691, AS3691A or AS3691B
Te
ch
ni
ca
am
lc s
on A
te G
nt
st
il
lv
al
id
Figure 19 – ePTSSOP Package Drawing Detail Dimenstions
10.3 DIE Delivery
Please contact austriamicrosystems for die delivery.
www.austriamicrosystems.com (ptr)
Revision 2.3
20 - 22
AS3691
Datasheet
11 Ordering Information
Table 7 – Ordering Information
Part Number
Marking
Package Type
Delivery Form
Description
1)
AS3691A
-orAS3691 1)
QFN 24
4x4mm
Tape and Reel
in Dry Pack
Package Size = 4x4x0.85mm,
Pitch = 0.5mm, Pb-Free;
10mV on VRES for ON=0
AS3691A-ZQFT
AS3691A
QFN 24
4x4mm
Trays
in Dry Pack
Package Size = 4x4x0.85mm,
Pitch = 0.5mm, Pb-Free;
10mV on VRES for ON=0
AS3691A-ZSDF2) (AS3691A)
Sorted
Wafers
Cut Dies on Foil
Sorted Wafers;
10mV on VRES for ON=0
AS3691B-ZQFP
QFN 24
4x4mm
Tape and Reel
in Dry Pack
Package Size = 4x4x0.85mm,
Pitch = 0.5mm, Pb-Free;
0mV on VRES for ON=0
AS3691A-ZTSP
2)
2)
AS3691B-ZTSP
Note:
1)
2)
Description:
lv
am
lc s
on A
te G
nt
st
il
AS3691B-ZSDF
AS3691B
al
id
AS3691A-ZQFP
(AS3691B)
AS3691A
AS3691B
Sorted
Wafers
Cut Dies on Foil
Sorted Wafers;
0mV on VRES for ON=0
ePTSSOP
Tape and Reel
in Dry Pack
Enhanced Power TSSOP (with power pad),
Body Size=4.4mm
Pitch = 0.65mm, Pb-Free;
10mV on VRES for ON=0
ePTSSOP
Tape and Reel
in Dry Pack
Enhanced Power TSSOP (with power pad),
Body Size=4.4mm
Pitch = 0.65mm, Pb-Free;
0mV on VRES for ON=0
AS3691 with 10mV on VRES for ON=0 can be marked with ‘AS3691’ or ‘AS3691A’ (identical
behavior)
Contact austriamicrosystems for availability
AS3691 Version, either A or B
AS3691A: 10mV on VRESx (x=1 to 4) if ONx = 0 (see ‘7 Detailed Functional Description’)
AS3691B: 0mV on VRESx (x=1 to 4) if ONx = 0 (see ‘7 Detailed Functional Description’)
ni
V …
ca
AS3691V-CPPD
Temperature range -20°C - 85°C
ch
C …
Package; QF for QFN, SD for sorted DIEs, TS for enhanced Power TSSOP
D…
Delivery From; P for Tape&Reel in Dry Pack, F for cut dies on foil, T for Trays in Dry Pack
Te
PP …
www.austriamicrosystems.com (ptr)
Revision 2.3
21 - 22
AS3691
Datasheet
Copyright
Copyright © 1997-2007, austriamicrosystems AG, Schloss Premstaetten, 8141 Unterpremstaetten, AustriaEurope. Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted,
merged, translated, stored, or used without the prior written consent of the copyright owner.
al
id
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
Diclaimer
ch
ni
ca
am
lc s
on A
te G
nt
st
il
lv
Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions
appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by
description regarding the information set forth herein or regarding the freedom of the described devices from
patent infringement. Austriamicrosystems AG reserves the right to change specifications and prices at any time
and without notice. Therefore, prior to designing this product into a system, it is necessary to check with
austriamicrosystems AG for current information.
This product is intended for use in normal commercial applications. Applications requiring extended temperature
range, unusual environmental requirements, or high reliability applications, such as military, medical life-support
or lifesustaining equipment are specifically not recommended without additional processing by
austriamicrosystems AG for each application. For shipments of less than 100 parts the manufacturing flow might
show deviations from the standard production flow, such as test flow or test location.
The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However,
austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not
limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect,
special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing,
performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise
or flow out of austriamicrosystems AG rendering of technical or other services.
Contact Information
Te
Headquarters
austriamicrosystems AG
A-8141 Schloss Premstätten, Austria
T. +43 (0) 3136 500 0
F. +43 (0) 3136 5692
For Sales Offices, Distributors and Representatives, please visit:
http://www.austriamicrosystems.com/contact
www.austriamicrosystems.com (ptr)
Revision 2.3
22 - 22
Similar pages