AS3685A/AS3685B

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: ams_sales@ams.com
Please visit our website at www.ams.com
austriamicrosystems
AS3685A/AS3685B
Datasheet
Datasheet
AS3685A/AS3685B
1 General Description
ƒ
Overtemperature Protection
ƒ
Automatic 800ms Flash Timeout to protect the
flash LED
ƒ
Two Device Variants:
− AS3685A: Direct control to select three
currents
− AS3685B: Single Pin Interface or Two Pin
Interface with Strobe Input; 17 different
currents can be selected
am
lc s
on A
te G
nt
st
il
Additionally the AS3685 limits the flash time
automatically to protect the flash LED.
lv
The AS3685 is low noise high efficiency capacitive
charge pump with 1:1, 1:1.5 and 1:2 operating
modes in a small 3x3mm DFN10 or a tiny 2x1.5mm
WL-CSP (Wafer Level Chip Scale Package)
package. It can drive one flash led at up to 1000mA
current. It supports flash/torch and indicator mode
for the flash led.
al
id
Ultra Small High Efficiency 1000mA Charge Pump for White
LED Flash
2 Key Features
ƒ
ƒ
High Efficiency capactive charge pump with 1:1,
1:1.5 and 1:2 modes
− 1:2 Mode can be disabled
(different device versions available)
ƒ
Up to 1000mA Led Current
ƒ
Automatic Charge Pump Mode switching (Up)
ƒ
LED cathode disconnect in Shutdown
Package
− DFN10 3x3mm (10 pins + exposed pad)
− WL-CSP (Wafer Level Chip Scale Package)
3x4 balls 0.5mm pitch (2x1.5mm)
3 Applications
ƒ
Flash / Torch for Mobile Phones, Digital
Cameras and PDA
4 Application Diagram
Figure 1 – Application Diagram of AS3685A/AS3685B
ni
ca
CFLY1 1.0 F
CBAT
2.2 F
Te
ch
VBAT
www.austriamicrosystems.com/AS3685
(ptr)
CFLY2 1.0 F
C1+ C1- C2+ C2VBAT
VCP
AS3685A
AS3685B
EN1
ILED
EN2
CVCP
2.2 F
DLED
ISET VSS
RTXMASK
RISET
Revision 2.2
1 - 24
AS3685A/AS3685B
Datasheet
Table of Contents
General Description........................................................................................................................................... 1
Key Features ..................................................................................................................................................... 1
Applications ....................................................................................................................................................... 1
Application Diagram .......................................................................................................................................... 1
Characteristics................................................................................................................................................... 3
5.1 Absolute Maximum Ratings..................................................................................................................... 3
5.2 Operating Conditions .............................................................................................................................. 3
5.3 Electrical Characteristics ......................................................................................................................... 4
6 Typical Operation Characteristics...................................................................................................................... 6
7 Detailed Functional Description ......................................................................................................................... 8
7.1 Low Noise Charge Pump ........................................................................................................................ 8
7.1.1 Mode Switching........................................................................................................................ 8
7.1.2 Soft Start .................................................................................................................................. 9
7.2 Current Source (Sink).............................................................................................................................. 9
7.2.1 AS3685A Current Setting ......................................................................................................... 9
7.2.2 AS3685B Current Setting ....................................................................................................... 12
7.2.3 AS3685A and AS3685B TXMask Function ............................................................................ 15
7.3 Protection Functions.............................................................................................................................. 16
7.3.1 Overtemperature Protection ................................................................................................... 16
7.3.2 Flash Timeout ........................................................................................................................ 16
7.4 Layout Recommendations..................................................................................................................... 16
8 External Components ...................................................................................................................................... 17
8.1 Capacitor and Resistor Selection .......................................................................................................... 17
8.2 Usage of PCB Wire Inductance............................................................................................................. 17
8.3 External Component Specifications ...................................................................................................... 17
9 Pinout and Packaging...................................................................................................................................... 18
9.1 DFN10 3x3mm ...................................................................................................................................... 18
9.1.1 Pin Assignments DFN10 3x3mm ........................................................................................... 18
9.1.2 Pin Descriptions DFN10 3x3mm ............................................................................................ 18
9.1.3 Package Drawings and Marking DFN10 3x3.......................................................................... 19
9.2 WL-CSP 2x1.5mm (Wafer Level Chip Scale Package) ......................................................................... 21
9.2.1 Pin Assignments WL-CSP 2x1.5mm...................................................................................... 21
9.2.2 Pin Descriptions WL-CSP 2x1.5mm....................................................................................... 21
9.2.3 Package Drawings and Marking WL-CSP 2x1.5mm .............................................................. 22
10 Ordering Information........................................................................................................................................ 23
Te
ch
ni
ca
am
lc s
on A
te G
nt
st
il
lv
al
id
1
2
3
4
5
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
2 - 24
AS3685A/AS3685B
Datasheet
5 Characteristics
5.1 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.
Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Parameter
Min
Max
Unit
VBATMAX
Maximum Supply Voltage
-0.3
7.0
V
IIN
Input Pin Current without causing
latchup
-25
+25
mA
TSTRG
Storage Temperature Range
-55
125
°C
Humidity
5
85
%
VESD
Electrostatic Discharge
-1000
1000
V
PT
Total Continuous Power Dissipation
TBODY
Notes:
1.
Non condensing
Norm: MIL 883 E Method 3015
W
DFN10 3x3mm, TA = 70°C 1
1.02
W
WL-CSP 2x1.5mm, TA = 70°C 1
16.3
mW/
°C
DFN10 3x3mm
14.7
mW/
°C
WL-CSP 2x1.5mm
Junction Temperature
150
°C
Body Temperature during Soldering
260
°C
am
lc s
on A
te G
nt
st
il
TJUNC
At 25ºC, Norm: Jedec 17
1.14
PT Derating Factor 2
PDERATE
Note
lv
Symbol
al
id
Table 1 – Absolute Maximum Ratings
according to IPC/JEDEC JSTD-020C
Depending on actual PCB layout and PCB used; for peak power dissipation during flashing see
document ‘AS3685 Thermal Measurements’
For 1A flash current see application notes ‘AN3685_1Aflash’ and ‘AN3685_1Aflash_thermal_1v0’.
The PT derating factor changes the total continuous power dissipation, if the ambient temperature
is different to 70°C. Therefore for e.g. 85°C calculate PT85°C = PT – PDERATE * (85°C – 70 °C)
2.
ca
5.2 Operating Conditions
Table 2 – Operating Conditions
VBAT
Parameter
Min
Typ
Max
Unit
Note
Battery Supply Voltage
3.0
3.6
5.5
V
Supply voltage range
Battery Supply Voltage,
Functionally working
2.6
V
AS3685 functionally working,
but not all parameters fulfilled
0.4
A
Depending on load current
and charge pump mode
2.0
A
Limited lifetime, max 20,000s
25
85
°C
1.0
4.0
μA
ni
Symbol
ch
VBATFUNC
Te
IBAT
Operating Current
TAMB
Ambient Temperature
IOFF
Off mode current
www.austriamicrosystems.com/AS3685
(ptr)
-30
Revision 2.2
EN1 = 0, EN2 = 0;
VBAT<=4.2V
3 - 24
AS3685A/AS3685B
Datasheet
Table 2 – Operating Conditions
IOPERATING
Min
Power Consumption without
load
Typ
Max
Unit
Note
0.85
mA
1:1 Mode
6.6
mA
1:1.5 Mode
8.1
mA
1:2 Mode
Max
Unit
Note
VBAT *
CPmode
V
CP-mode is 1, 1.5 or 2
(automatically selected)
5.3 Electrical Characteristics
Table 3 – Charge Pump Characteristics
Parameter
VCPOUT
V(VCP) Output voltage
without load – do not short to
VSS
Output limitation
Min
Charge Pump effective
Resistance
RCP
Eta
Typ
5.4
5.6
internally limited
0.28
0.53
Ω
1:1 Mode
VBAT = 3.6V, ICPOUT = 200mA
1.37
2.00
Ω
1:1.5 Mode
VBAT = 3.3V, ICPOUT = 500mA,
TJUNCTION<=85°C
1.95
2.44
Ω
1:2 Mode
VBAT = 3.0V, ICPOUT=700mA,
TJUNCTION<=85°C
93
%
Vin=3.0V-4.5V, Iout=100mA
(Charge Pump alone)
mVpp
Vin=3.0-4.5V, Iout=350mA,
am
lc s
on A
te G
nt
st
il
Symbol
al
id
Parameter
lv
Symbol
Efficiency
75
Output ripple voltage
fclk
Operating Frequency
tUP_DEB_LONG
Initial Mode Switching
Debounce Time
256
μs
tUP_DEB
Mode Switching Debounce
Time
16
μs
ca
VRIPPLE
100
-20%
1.0
+20%
MHz
Mode switching up-debounce
time after enabling of the
charge pump or after mode
switching between 1:1 to 1:1.5
Mode switching up-debounce
time in normal operation
Table 4 – Current Source (Sink) Characteristics
ILED
Parameter
ni
Symbol
Output Current Range
Current Setting Accuracy
VISET
Current Generator Set Point
Voltage (pin ISET)
ch
IACCURACY
IISET
Current Generator operating
range
IFLASH2ISET
Flash Current to Bias Current
Ratio
Te
Min
www.austriamicrosystems.com/AS3685
(ptr)
-10%
Typ
Max
Unit
Note
700
1000
mA
700mA: RISET = 14.2kΩ
1000mA: RISET = 10kΩ
500
+10%
mA
Measured with RISET = 19.9kΩ
and maximum flash current
1.3
10.0
V
130
7650
μA
A/A
IISET = VISET / RISET
if the resulting bias current is
higher than 200μA (typ.), the
current source is disabled
AS3685A, EN1=1, EN2=1 or
AS3685B at full flash current
(700mA with RISET = 14.2kΩ)
Revision 2.2
4 - 24
AS3685A/AS3685B
Datasheet
Table 4 – Current Source (Sink) Characteristics
ITORCH2ISET
Torch Current to Bias Current
Ratio
VSWITCH
Mode Switching Threshold on
V(ILED) between 1:1 -> 1:1.5
and 1:1.5 -> 1:2
Min
Typ
Max
Unit
Parameter
AS3685A, EN1=0, EN2=1
1639
A/A
400
mV
AS3685A, EN1=1, EN2=1 or
AS3685B with ILED>350mA
(with RISET = 14.2kΩ)
(150mA with RISET = 14.2kΩ)
150
200
250
mV
All lower currents
Min
Typ
Max
Unit
Note
For Pins EN1 and EN2
Table 5 –Digital Interface characteristics
Symbol
Note
High Level Input voltage
1.5
VBAT
V
VIL
Low Level Input voltage
0.0
0.5
V
ILEAKAGE
Input pin leakage current
-10
10
μA
tPULSEWIDTH
Pulsewidth for signals on EN1
and EN2 (high or low pulses)
1.0
unlimited
μs
Max
Unit
Do not leave EN1 and EN2
floating; (47kΩ pulldowns can
be used)
am
lc s
on A
te G
nt
st
il
VIH
al
id
Parameter
lv
Symbol
Table 6 – Protection Functions
Symbol
Parameter
Min
Typ
TOVTEMP
Overtemperature protection
140
°C
TOVTEMPHYST
Overtemperature protection
Hysteresis
5
°C
tFLASHTIMEOUT
Flash Timeout Time
800
+20%
ms
AS3685A, EN1=1, EN2=1 or
AS3685B flash modes
Te
ch
ni
ca
-20%
Note
If the junction temperature
exceeds TOVTEMP, the current
sink will be disabled and the
charge pump switched back
into 1:1 mode until the
temperature drops below
TOVTEMP - TOVTEMPHYST
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
5 - 24
AS3685A/AS3685B
Datasheet
6 Typical Operation Characteristics
Figure 2 – Efficiency vs. Battery Voltage (with Lumiled PWF1)
Figure 3 – Battery Current vs. Battery Voltage (with Lumiled PWF1)
1.6
100
ILED=100m
ILED=200m
ILED=300m
ILED=400m
90
1.4
1.2
ILED=500m
80
70
ILED=700m
ILED=600m
0.6
ILED=700m
ILED=500m
ILED=400m
ILED=300m
0.4
50
ILED=200m
0.2
ILED=50m
ILED=100m
lv
ILED=600m
60
0.8
0.0
40
2.8
3.2
3.6
4.0
4.4
4.8
2.8
5.2
3.2
3.6
4.0
5.2
Figure 5 – Linearty of Current Sink
0.8
0.7
ILED=700m
0.6
0.6
ILED=500m
0.3
ILED [A]
ILED=300m
ILED=100m
0.1
0.4
ILED=300m
ILED=200m
0.2
ILED=100m
0.1
ILED=50m
ILED=50m
0.0
2.8
ILED=500m
ILED=400m
0.3
ILED=200m
0.2
ILED=600m
0.5
ILED=400m
0.4
ILED=700m
0.7
ILED=600m
0.5
ILED [A]
4.8
am
lc s
on A
te G
nt
st
il
Figure 4 – LED current I(ILED) vs. Battery Voltage (with Lumiled PWF1)
3.2
3.6
4.0
4.4
4.8
0.0
5.2
0.0
VBAT [V]
0.5
1.0
1.5
2.0
2.5
VILED [V]
Figure 6 –I(ILED) vs. R(ISET) (Flash and Torch Mode of AS3685A)
Figure 7 – Startup of AS3685A -- ILED Current
ca
1200
1000
ni
Flash Mode
800
600
ch
ILED [mA]
4.4
VBAT [V]
VBAT [V]
0.8
al
id
1.0
IBAT [A]
Efficiency of Charge Pump [%]
ILED=50m
400
200
Te
Torch Mode
0
0k
20k
40k
60k
80k
100k
120k
140k
ILED 500mA/div 100µs/div
VBAT=3.3V, ILED=700mA
R ISET [Ohm]
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
6 - 24
AS3685A/AS3685B
Datasheet
Figure 9 – Shutdown of AS3685A -- IBAT Current
lv
al
id
Figure 8 – Startup of AS3685A -- IBAT Current
IBAT 500mA/div 100µs/div
VBAT=3.3V, ILED=700mA
am
lc s
on A
te G
nt
st
il
IBAT 500mA/div 100µs/div
VBAT=3.3V, ILED=700mA
Figure 10 – Typical Operating Waveforms 1:1.5 Mode
Figure 11 – Typical Operating Waveforms 1:2 Mode
VCP ac-coupled, 50mV/div 250ns/div
VBAT=3.3V, ILED=500mA
Te
ch
ni
ca
VCP ac-coupled, 100mV/div 1µs/div
VBAT=3.3V, ILED=500mA
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
7 - 24
AS3685A/AS3685B
Datasheet
7 Detailed Functional Description
Figure 12 – Internal Circuit Diagram of AS3685A/AS3685B
C2+
C2-
Low Noise
Charge Pump
1:1, 1:1.5, 1:2 Modes
VBAT
VCP
al
id
VBAT
C1-
clk
mode
soft_limit
1MHz
5.3V
Overtemp
Detect
Vswitch
EN1
EN2
Digital
Control
ILED
am
lc s
on A
te G
nt
st
il
EN2
EN1
lv
C1+
1.3V
Different Control Logic
for AS3685A and AS3685B
TXMask
AS3685
ISET
VSS
7.1 Low Noise Charge Pump
The AS3685 charge pump uses two external flying capacitors to generate output voltages higher than the battery
voltage. The charge pump can operate in three different modes:
ƒ
ni
ƒ
1:1 Bypass Mode or Off Mode
− Battery input and output are connected by a low-impedance switch
− Battery current = output current
1:1.5 Mode
− The output voltage is 1.5 times the battery voltage (without load)
− Battery current = 1.5 times output current
1:2 Mode
− The output voltage is 2 times the battery voltage (without load)
− Battery current = 2 times output current
ca
ƒ
ch
The flying capacitors are switched at the fixed frequency fclk.
7.1.1 Mode Switching
Te
The AS3685 monitors the voltage at the current sink V(ILED) and if this voltage falls below VSWITCH, for a time
longer than the debounce time, the charge pump automatically switches into a higher mode. The debounce time
is set to tUP_DEB_LONG at enabling of the charge pump or immediately after a 1:1 to 1:1.5 mode change. Afterwards
the debounce time is reduced to tUP_DEB. (This allows the LED current to settle properly on startup or after a
mode change)
The charge pump enters always 1:1 mode in off mode or in case of overtemperature.
It is possible to avoid the 1:2 mode (factory programmable) to limit the battery current to 1.5 times the output
(=LED) current.
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
8 - 24
AS3685A/AS3685B
Datasheet
7.1.2 Soft Start
The soft start mechanism reduces the inrush current. Battery current is smoothed when switching the
charge pump on and also at each switching condition. This precaution reduces electromagnetic radiation
significantly.
7.2 Current Source (Sink)
lv
al
id
The AS3685 operates in three different modes:
ƒ
Indicator Mode: A small (average) current is used to obtain an indication function with the flash LED (e.g.
indication for camera operation)
ƒ
Torch Mode: A moderate current of e.g. 150mA allows the use of the flash LED as a torch or video light
ƒ
Flash Mode: A high current of e.g. 700mA (up to 1000mA) is set for a high brightness flash. Only in this
mode, the flash timeout timer limits the total flash time.
ƒ
Pulsed Indicator Mode (only AS3685A): The control device sends a short sequence to the AS3685A and the
AS3685A enables the flash LED for a defined fixed duration (torch current setting). This duration is
controlled by the AS3685A and the control device does not need to start an internal timer function.
am
lc s
on A
te G
nt
st
il
The current through the LED and the operating mode is controlled by the two digital pins EN1 and EN2. There
are two versions of the AS3685 available: AS3685A and AS3685B. The only difference between these versions
is the digital interface as shown below:
7.2.1 AS3685A Current Setting
For the AS3685A, the operating mode and the current through the LED is defined by the following table:
Table 7 – AS3685A Current Settings
ILED
EN1
EN2
0
1
0
0
1
1
1
Notes:
ILED/IISET
0
(Off)
10kΩ
0mA
0mA
0%
4.7mA average
6.7mA average
0.67%
Indicator
(=150mA with
1/32 duty cycle1))
(=214mA with
1/32 duty cycle1))
(=21.4% /
32)
(=ITORCH2ISET/32)
Torch
150mA
214mA
21.4%
1639
(=ITORCH2ISET)
Flash
700mA
1000mA
100%
7650
(=IFLASH2ISET)
52.2
The on-time for indicator mode is 1μs, off time 31μs (32μs = 32.25kHz)
ni
1)
Off
Percent of
Full Scale
14.2kΩ
ca
0
for RISET =
Mode
Where IISET is:
ch
VISET
RISET
1.3 V
RISET
Te
IISET
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
9 - 24
AS3685A/AS3685B
Datasheet
Application Hint: To obtain higher torch currents use the following circuit:
Figure 13 – AS3685A Increasing Torch Current
VBAT
VBAT
AS3685A
EN1
EN1
EN2
EN2
ISET
al
id
RTORCH
7.2.1.1 AS3685A Pulsed Indicator Mode
am
lc s
on A
te G
nt
st
il
The torch mode is controlled by EN1=0 and EN2=1 as following figure shows:
lv
RISET
Figure 14 – AS3685A Torch Mode
EN1
EN2
ILED
Torch
Current
typ. 64µs
off
off
t
ca
To allow an indication function using short pulses (with torch current settings), the pulsed indicator mode can be
used. The control device sends a setup sequence (total time required: less than 128μs) to ‘program’ the
AS3685A, and the AS3685A enables its current sink for the duration tTORCH (the current used is exactly the torch
current setting). Therefore the control does not need to setup an timer to accurately define the duration of the
indicator pulse.
Te
ch
ni
The duration tTORCH can be setup from 1ms to 15ms depending on the number of pulses on EN2 as shown in the
following figure and table:
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
10 - 24
AS3685A/AS3685B
Datasheet
Figure 15 – AS3685A Pulsed Indicator Mode
Set duration of Torch-Pulse (tTORCH)
with number of pulses on pin EN2
EN1
EN2
max. 128µs
ILED
min tPULSEWIDTH
(1µs)
tTORCH
typ. 64µs
off
Table 8 – AS3685A tTORCH timings
H-L Pulses on EN2
4
5
6
7
8
9
10
11
12
13
14
15
16
ignored (noise filter)
1ms
2ms
3ms
4ms
5ms
6ms
7ms
8ms
9ms
10ms
11ms
12ms
13ms
14ms
15ms
Te
ch
ni
≥17
0ms
am
lc s
on A
te G
nt
st
il
3
tTORCH
ca
1,2
t
lv
off
al
id
Torch
Current
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
11 - 24
AS3685A/AS3685B
Datasheet
7.2.2 AS3685B Current Setting
The current through the LED (ILED) can be set in several steps using the following waveforms:
Figure 16 – AS3685B Current Setting Method A
Define
Method A
Set current with
number of pulses
EN1
EN2
min.
tPULSEWIDTH
ILED
typ. 64µs
al
id
Current can be increased
if required
Flash/Strobe/Indicatior function
dependent on number of pulses
off
t
lv
off
am
lc s
on A
te G
nt
st
il
For method A, the current is started after a certain time after the first rising edge of EN1. The AS3685B chooses
method A, if EN1 is high at the first rising edge of EN2.
Figure 17 – AS3685B Current Setting Method B
Set current with
number of pulses
Define
Method B
EN1
EN2
Current can be
increased if required
ILED
no time limit
off
typ. 64µs
Flash/Strobe/Indicatior function
dependent on number of pulses
min tPULSEWIDTH
off
t
For method B, the current is started after the second rising edge of EN2. The AS3685B chooses method B, if
EN1 is low at the first rising edge of EN2.
Any high or low level duration for EN1 or EN2 should not be shorter than tPULSEWIDTH.
ca
The actual number of pulses on the pin EN1 (applies for methods A and B) define the mode and the current
settings for the AS3685B:
Table 9 – AS3685B Current Settings
Mode
ni
H-L-H Pulses on EN1
EN1=EN2=0
Off
ch
0
1
Indicator
Te
2
3
4
Torch
5
6
www.austriamicrosystems.com/AS3685
(ptr)
Flash
ILED
(for RISET = 14.2kΩ)
ILED
(for RISET = 10kΩ)
ILED/IISET
0mA
0%
0
(Off)
4.7mA average
6.7mA
(=150mA with
1/32 duty cycle1) )
(=214mA with
1/32 duty cycle1))
(=ITORCH2ISET/32)
41mA
60mA
448
85mA
120mA
929
129mA
180mA
1410
173mA
250mA
1891
217mA
310mA
2371
Revision 2.2
52.2
12 - 24
AS3685A/AS3685B
Datasheet
Table 9 – AS3685B Current Settings
Mode
ILED
(for RISET = 14.2kΩ)
ILED
(for RISET = 10kΩ)
ILED/IISET
7
Flash
261mA
370mA
2852
8
305mA
440mA
3333
9
349mA
500mA
3814
10
393mA
560mA
4295
11
437mA
620mA
4776
12
481mA
690mA
13
525mA
750mA
14
569mA
810mA
15
613mA
880mA
16
657mA
940mA
17
700mA
1000mA
Where IISET is:
IISET
5257
5737
6218
lv
6699
7180
7650
(=IFLASH2ISET)
am
lc s
on A
te G
nt
st
il
Notes: 1) The on-time for indicator mode is 1μs, off time 31μs (32μs = 32.25kHz)
al
id
H-L-H Pulses on EN1
VISET
RISET
1.3 V
RISET
7.2.2.1 AS3685B Single Wire Interface
Using the following application schematic, a single GPIO pin can be used to control the mode and current of the
AS3685B:
Figure 18 – AS3685B Single Wire Interface
Vbat
VBAT
AS3685B
EN1
EN1
ca
RSINGLE
ISET
ni
single GPIO Pin to set
indicator/torch/flash mode
EN2
CSINGLE
1nF
ch
An example driving waveform can be (this uses method A as shown above in section ‘AS3685B Current
Settings’):
Te
Figure 19 – AS3685B Example Single Wire Interface driving waveform
EN1
(EN2)
off
Set current with
number of pulses
www.austriamicrosystems.com/AS3685
(ptr)
Flash/Strobe/Indicatior function
dependent on number of previous pulses
Revision 2.2
off
13 - 24
AS3685A/AS3685B
Datasheet
The low time of the pulses on EN1 for setting the current should be kept short. Then the (generated) signal on
pin EN2 will stay at a high level during this time ensuring correct operation. RSINGLE should be chosen to fit to the
actual driving waveform on EN1.
7.2.2.2 AS3685B Two Wire Interface with Strobe Input
Using the following application schematic, the AS3685B current and mode can be set accurately and the camera
can directly control the exact strobe time:
Vbat
al
id
Figure 20 – AS3685B Two Wire Interface with strobe input
VBAT
Two GPIO Pins to set
current and mode
EN1
EN2
EN2
ISET
STROBE
RSTROBE
am
lc s
on A
te G
nt
st
il
Optional
Strobe Input
lv
AS3685B
EN1
An example driving waveform can be (this uses method B as shown above in section ‘AS3685B Current
Settings’):
Figure 21 – AS3685B Example Two Wire Interface driving waveform
Enable/Disable current directly by the
camera module using the 'STROBE' input
EN1
EN2
STROBE
off
Set current with
number of pulses
Flash/Strobe/Indicatior function
dependent on number of previous pulses
GPIO output driving EN2
directly defines input EN2
Te
ch
ni
ca
GPIO output driving EN2 directly is
tristated and 'STROBE'
defines input EN2
off
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
14 - 24
AS3685A/AS3685B
Datasheet
7.2.3 AS3685A and AS3685B TXMask Function
If the battery has to supply two high currents at the same time (e.g. the AS3685 flash and a RF-power amplifier) it
is possible, that the total current causes a high voltage drop on the battery resulting in a shutdown of the
complete system. In order to avoid this shutdown, the AS3685 (AS3685A or AS3685B) can reduce its current
with the signal ‘TXMask’ using the following circuit:
Figure 22 – TXMask function of the AS3685
VBAT
EN1
EN1
EN2
EN2
AS3685A
AS3685B
al
id
VBAT
ISET
RTXMASK
lv
TXMask
am
lc s
on A
te G
nt
st
il
RISET
The TXMask signal is connected to e.g. the (RF-) power amplifier enable pin (active high if the PA is enabled).
This reduces the flash current if the power amplifier is enabled and avoids the unexpected shutdown of the
system.
Note: The internal flash timeout timer (tFLASHTIMEOUT) to limit the total flash duration, is not affected by the
TXMask function (see also section ‘Flash Timeout’).
The IISET current (current into the pin ISET) for TXMask = 0 can be calculated with:
IISET , TXMask
0
V ISET
VISET
R ISET
RTXMASK
1.3 V
RISET
1.3 V
R TXMASK
For TXMask = 1 the current IISET is reduced to:
IISET , TXMask
1
V ISET
V ISET V TXMask
R ISET
R TXMASK
1.3 V
RISET
1.3 V V TXMask
RTXMASK
V(TXMask) is the actual voltage for the high level (‘1’) for the signal TXMask
ca
The maximum flash current ILEDMAX for TXMask=0 or 1 can be calculated according to the following formula
using the above obtained IISET values:
ILEDMAX IFLASH2BIAS IISET 7650 I ISET
Te
ch
ni
Choose the values for RISET and RTXMASK according to your application requirements.
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
15 - 24
AS3685A/AS3685B
Datasheet
7.3 Protection Functions
7.3.1 Overtemperature Protection
If the AS3685 junction temperature exceeds TOVTEMP, the current sink will be disabled and the charge pump
forced into 1:1 mode. If the junction temperature drops below TOVTEMP – TOVTEMPHYST, the device enables the
current sink again and the charge pump resumes normal operation.
7.3.1.1 LED Shortcircuit protection
al
id
If the LED is shorted (VCP to ILED), then depending on the set current and the resulting high power dissipation
inside the AS3685, the overtemperature protection will trigger. This protects the AS3685 and the system against
damage. If the AS3685 is in off-mode, then shorting of the diode will have no influence on the system.
Note: Do not short VCP to VSS if the supply is not current limited (e.g. by an internal protection inside the
battery), as there is an internal diode between VBAT (anode) and VCP (cathode).
7.3.2 Flash Timeout
am
lc s
on A
te G
nt
st
il
lv
The flash duration of a single flash is limited automatically to tFLASHTIMEOUT (applies only for ‘Flash’ mode(s)).
This protects the flash LED against thermal damage.
7.4 Layout Recommendations
To improve the heat dissipation, use a massive ground plane.
Figure 23 – AS3685 DFN10 3x3mm Layout Recommendation
CFLY1
CFLY2
AS3685
VBAT
EN1
VSS
1
2
3
4
5
CBAT
ILED
10
9
8
7
6
EN2
RISET
VIA, which is connected to
the ground plane, too
CVCP
'Normal' VIA
VCP
ca
Use ground place
connected to VSS
Top Layer
Bottom Layer
ni
Figure 24 – AS3685 WL-CSP 2x1.5mm Layout Recommendation
Use ground plane
connected to VSS
ch
VSS
CBAT
CVCP
EN1
Te
VBAT
A1 A1
A2
A3
B1
B2
B3
VCP
RISET
EN2
ILED
C1 C2 C3
D1 D2 D3
CFLY2
AS3685
CFLY1
Top Layer
Inner Layer
Bottom Layer
VIA, which is connected to
the ground plane, too
'Normal' VIA
Micro VIA between
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
16 - 24
AS3685A/AS3685B
Datasheet
8 External Components
8.1 Capacitor and Resistor Selection
Use low-ESR ceramic capacitors with X7R or X5R dielectric. These capacitors allow good filtering and have a
wide temperature range. The connections of all external capacitors should be kept as short as possible. All
resistors should have a tolerance of ±1%.
8.2 Usage of PCB Wire Inductance
al
id
The inductance between the battery and pin VBAT can be used as a filter to reduce disturbance on the battery.
Instead of using one capacitor (CBAT) it is recommended to split CBAT into CBAT1 and CBAT2 with the capacitance
of
CBAT1 = CBAT2 = CBAT
lv
It is recommended to apply a minimum of 20nH (maximum 200nH) with low impedance. This inductance can be
realized on the PCB without any discrete coil. Assuming that a 1mm signal line corresponds to approximately
1nH (valid if the length (L) is significantly bigger than the width (W) of the line (L/W <10)), a line length of
20mm < L < 200mm
is recommended. The shape of the line is not important.
am
lc s
on A
te G
nt
st
il
Figure 25 – PCB Wire Inductance Example1
L
Battery
Connector
AS3685
Pin VBAT
CBAT1
VSS
LTOTAL = L
CBAT2
VSS
Figure 26 – PCB Wire Inductance Example2
L1
CBAT1
VSS
AS3685
Pin VBAT
CBAT2
L2
Battery
Connector
LTOTAL = L1 + 10*L2
VSS
ca
8.3 External Component Specifications
Table 10 – External Components List
Tol
(Min)
Rating
(Max)
2.2μF
+/-20%
6.3V
CFLY1, CFLY2
1.0μF
+/-20%
6.3V
CVCP
2.2μF
+/-20%
6.3V
Min
Te
ch
CBAT 1
RISET
RTXMASK
DLED
Notes:
Value
Typ
ni
Part
10kΩ
Max
130kΩ
See section ‘TXMask function’
Notes
Package
(min)
Ceramic, X5R
0603
e.g. Murata GRM21BR71A225KA01L
Ceramic, X5R
e.g. Murata GRM188R60J105K
Ceramic, X5R
e.g. Murata GRM21BR71A225KA01L
0603
(0402, 0405)
0603
+/-1%
Current Set Resistor
0201
+/-1%
TXMask Set Resistor
0201
Flash Led
1. See section ‘Usage of PCB Wire Inductance’
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
17 - 24
AS3685A/AS3685B
Datasheet
9 Pinout and Packaging
9.1 DFN10 3x3mm
9.1.1
Pin Assignments DFN10 3x3mm
Figure 27 –Pin Assignments DFN10 3x3mm
8
1
C1+ C1- C2+ C22
VBAT
VCP
4
5
AS3685A
EN1 AS3685B
ILED
EN2
9
7
ISET VSS
Exposed Pad
am
lc s
on A
te G
nt
st
il
6
al
id
10
lv
3
9.1.2 Pin Descriptions DFN10 3x3mm
Table 11 – Pin Type Descriptions DFN10 3x3mm
Pin Type
Description
AI/O
Analog Pin
DI
Digital Input
S
Supply Pin
Table 12 – Pin Descriptions DFN10 3x3mm
Pin Number
Pin Name
Type
Description
1
C2-
AI/O
Flying Capacitor 2 connection – connect 1μF ceramic
capacitor CFLY2 between C2- and C2+
VBAT
S
C1+
AI/O
2
ca
3
4
6
EN1
DI
ISET
AI/O
EN2
DI
ch
7
AI/O
ni
5
VCP
Battery Supply Voltage
Flying Capacitor 1 connection – connect 1μF ceramic
capacitor CFLY1 between C1- and C1+
Charge Pump Output voltage – connect flash LED anode
to this pin and add CVCP capacitor with 2.2μF to VSS
Digital Control Signal EN1
Current Generator input pin – connect current set resistor
RISET between this pin and VSS (and optional RTXMASK)
Digital Control Signal EN2
C2+
AI/O
Flying Capacitor 2 connection – connect 1μF ceramic
capacitor CFLY2 between C2- and C2+
9
ILED
AI/O
Current Source input pin – connect flash LED cathode to
this pin
10
C1-
AI/O
Flying capacitor 1 connection – connect 1μF ceramic
capacitor CFLY1 between C1- and C1+
Exposed Pad
VSS
S
Te
8
www.austriamicrosystems.com/AS3685
(ptr)
Ground Connection – a proper thermal connection with
several vias to the ground plane is recommended
Revision 2.2
18 - 24
AS3685A/AS3685B
Datasheet
9.1.3 Package Drawings and Marking DFN10 3x3
am
lc s
on A
te G
nt
st
il
Top View
lv
AYWW
XZZ
AS8x
al
id
Figure 28 – DFN10 – 3x3mm Pacakge Drawing
ch
ni
ca
Bottom View
(rotated)
Te
Marking:
Line 1: AYWW
A = Pb-Free Identifier
Y = Year
WW = Week
Line 2: XZZ
X = Plant Identifier
ZZ = Letters of Free Choice
Line 3: AS8A for AS3685A or AS8B for AS3685B
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
19 - 24
AS3685A/AS3685B
Datasheet
Te
ch
ni
ca
am
lc s
on A
te G
nt
st
il
lv
al
id
Figure 29 – DFN10 – 3x3mm Detail Dimensions
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
20 - 24
AS3685A/AS3685B
Datasheet
9.2 WL-CSP 2x1.5mm (Wafer Level Chip Scale Package)
9.2.1 Pin Assignments WL-CSP 2x1.5mm
Figure 30 – WL-CSP 2x1.5mm Pin Assignments
B1
D2
C2
D1
VBAT
VCP
B2
A1
AS3685A
EN1 AS3685B
ILED
EN2
C3
B3
ISET VSS
A3
A2,D3
am
lc s
on A
te G
nt
st
il
9.2.2 Pin Descriptions WL-CSP 2x1.5mm
lv
C1
al
id
C1+ C1- C2+ C2-
Table 13 – Pin Type Descriptions WL-CSP 2x1.5mm
Pin Type
Description
AI/O
Analog Pin
DI
Digital Input
S
Supply Pin
Table 14 – Pin Descriptions WL-CSP 2x1.5mm
Pin Number
Pin Name
Type
A1
EN1
DI
Digital Control Signal EN1
VSS
S
Ground Connection – a proper thermal connection to the
ground plane is recommended
ISET
AI/O
Current Generator input pin – connect current set resistor
RISET between this pin and VSS (and optional RTXMASK)
C1+
AI/O
Flying Capacitor 1 connection – connect 1μF ceramic
capacitor CFLY1 between C1- and C1+
VCP
AI/O
Charge Pump Output voltage – connect flash LED anode
to this pin and add CVCP capacitor with 2.2μF to VSS
EN2
DI
Digital Control Signal EN2
VBAT
S
Battery Supply Voltage
C2+
AI/O
Flying Capacitor 2 connection – connect 1μF ceramic
capacitor CFLY2 between C2- and C2+
A2
A3
B1
ca
B2
C1
ch
C2
ni
B3
Description
ILED
AI/O
Current Source input pin – connect flash LED cathode to
this pin
D1
C2-
AI/O
Flying Capacitor 2 connection – connect 1μF ceramic
capacitor CFLY2 between C2- and C2+
D2
C1-
AI/O
Flying capacitor 1 connection – connect 1μF ceramic
capacitor CFLY1 between C1- and C1+
D3
VSS
S
Te
C3
www.austriamicrosystems.com/AS3685
(ptr)
Ground Connection – a proper thermal connection to the
ground plane is recommended
Revision 2.2
21 - 24
AS3685A/AS3685B
Datasheet
9.2.3 Package Drawings and Marking WL-CSP 2x1.5mm
lv
al
id
Figure 31 – WL-CSP 2x1.5mm Package Drawing
Marking:
austriamicrosystems logo
AS3685x
x = A for AS3685A, B for AS3685B,
A2 for AS3685A with 1:2 mode, B2 for AS3685A with 1:2 mode
AYWWIZZ
A = Pb-Free Identifier
Y = Year
WW = Week
I = Plant Identifier
ZZ = Letters of Free Choice
am
lc s
on A
te G
nt
st
il
Line 1:
Line 2:
Line 3:
Te
ch
ni
ca
Figure 32 – WL-CSP 2x1.5mm Detail Dimensions
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
22 - 24
AS3685A/AS3685B
Datasheet
10 Ordering Information
Table 15 – Delivery Information
AS3685A-ZWLT2Y80
WL-CSP
2x1.5mm
AS3685A2
AS8A
DFN 10 3x3mm
Delivery Form
Description
Tape&Reel
AS3685A Interface
Wafer Level Chip Scale Package,
Size 2x1.5mm, 4x3 balls, 0.5mm pitch,
RoHS compliant / Pb-free,
800ms flash timeout, 1:2 mode locked
Tape&Reel
AS3685A Interface
Wafer Level Chip Scale Package,
Size 2x1.5mm, 4x3 balls, 0.5mm pitch,
RoHS compliant / Pb-free,
800ms flash timeout, 1:2 mode
enabled 1
Tape&Reel
AS3685A Interface
DFN Package, 3x3mm, 10 pins, 0.4mm
pitch, RoHS compliant / Pb-free,
800ms flash timeout, 1:2 mode
enabled1
am
lc s
on A
te G
nt
st
il
Description:
WL-CSP
2x1.5mm
AS3685A
AS3685A-ZDFT2Y80
AS3685B-ZDFT2Y80
Package Type
al
id
AS3685A-ZWLT2N80
Marking
lv
Part Number
AS8B
DFN 10 3x3mm
Tape&Reel
AS3685B Interface
DFN Package, 3x3mm, 10 pins, 0.4mm
pitch, Pb-Free,
800ms flash timeout, 1:2 mode enabled
AS3685V-ZPPT-2X80
AS3685
AS3685 Interface Version:
A = AS3685A: Direct control to select three different currents
B = AS3685B: Single or Two pin interface with strobe; 17 different current settings
Z
…
Temperature range:
Z = -30°C – 85°C
PP
…
Package:
WL = Wafer Level Chip Scale Package
DF = DFN10
-
T
…
Delivery Form:
T = Tape&Reel
Charge Pump Mode Locking:
2N = 1:2 mode locked (device can only use 1:1 and 1:1.5 mode)
2Y = 1:2 mode available (device can use 1:1, 1:1.5 and 1:2 mode)
ni
-
ca
…
V
…
ch
2X
…
Flash Timeout time programming
80 = 800ms flash timeout time
Te
80
1
If 1000mA flash LED current is used it is usually required to allow 1:2 mode (due to the high forward
voltage of the LED).
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
23 - 24
AS3685A/AS3685B
Datasheet
Copyright
Copyright © 1997-2010, austriamicrosystems AG, Tobelbaderstrasse 30, 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.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
Diclaimer
ni
ca
am
lc s
on A
te G
nt
st
il
lv
al
id
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 life-sustaining 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
ch
Contact Information
Te
Headquarters
austriamicrosystems AG
Tobelbaderstrasse 30
Schloss Premstätten
A-8141 Austria
Tel:
Fax:
+43 (0) 3136 500 0
+43 (0) 3136 525 01
For Sales Offices, Distributors and Representatives, please visit:
http://www.austriamicrosystems.com/contact
www.austriamicrosystems.com/AS3685
(ptr)
Revision 2.2
24 - 24