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AS3685C
Datasheet
Datasheet
austriamicrosystems
AS3685C
Ultra Small High Efficiency 1000mA Charge Pump for White
LED Flash with Two Wire Serial Interface
Additionally the AS3685 limits the flash time
automatically to protect the flash LED.
2 Key Features
High Efficiency capactive charge pump with 1:1,
1:1.5 and 1:2 modes
−
1:2 Mode can be disabled by interface
Up to 1000mA Led Current
Automatic Charge Pump Mode switching (Up)
4 Application Diagram
Figure 1 – Application Diagram of AS3685C
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Two Wire Interface
−
Accurate Control of Currents and Modes
Package
−
DFN10 3x3mm (10 pins + exposed pad)
−
WL-CSP (Wafer Level Chip Scale Package)
3x4 balls 0.5mm pitch (2x1.5mm)
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.
LED cathode disconnect in Shutdown
Overtemperature Protection
Automatic Flash Timeout to protect the LED
−
Adjustable between off, 100ms…1500ms
3 Applications
Flash / Torch for Mobile Phones, Digital
Cameras and PDA
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1 General Description
AS3685C
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 AS3685 TXMask Function...................................................................................................... 12
7.3 Protection Functions.............................................................................................................................. 13
7.3.1 Overtemperature Protection ................................................................................................... 13
7.3.2 Flash Timeout ........................................................................................................................ 13
7.4 Layout Recommendations..................................................................................................................... 13
8 External Components ...................................................................................................................................... 14
8.1 Capacitor and Resistor Selection .......................................................................................................... 14
8.2 Usage of PCB Wire Inductance............................................................................................................. 14
8.3 External Component Specifications ...................................................................................................... 14
9 Pinout and Packaging...................................................................................................................................... 15
9.1 DFN10 3x3mm ...................................................................................................................................... 15
9.1.1 Pin Assignments DFN10 3x3mm ........................................................................................... 15
9.1.2 Pin Descriptions DFN10 3x3mm ............................................................................................ 15
9.1.3 Package Drawings and Marking DFN10 3x3.......................................................................... 16
9.2 WL-CSP 2x1.5mm (Wafer Level Chip Scale Package) ......................................................................... 18
9.2.1 Pin Assignments WL-CSP 2x1.5mm...................................................................................... 18
9.2.2 Pin Descriptions WL-CSP 2x1.5mm....................................................................................... 18
9.2.3 Package Drawings and Marking WL-CSP 2x1.5mm .............................................................. 19
10 Ordering Information........................................................................................................................................ 20
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4
5
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AS3685C
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.
Table
1 – Absolute Maximum Ratings
Symbol
V
BATMAX
I
IN
T
STRG
V
ESD
PT
Parameter
Maximum Supply Voltage
Input Pin Current without causing
latchup
Storage Temperature Range
Humidity
Electrostatic Discharge
Min
-0.3
-25
-55
5
Max
7.0
+25
125
85
Unit
V
mA
°C
%
V
Note
At 25ºC, Norm: Jedec 17
Total Continuous Power Dissipation
P
DERATE
T
JUNC
T
BODY
Notes:
1.
2.
Body Temperature during Soldering
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 PT
85°C
= PT – P
DERATE
* (85°C – 70
°C)
5.2 Operating Conditions
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Table
2 – Operating Conditions
Symbol
VBAT
Parameter
Battery Supply Voltage
VBATFUNC
Battery Supply Voltage,
Functionally working
Operating Current
I
BAT
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T
AMB
I
OFF
Ambient Temperature
Off mode current
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Non condensing
-1000
1000
1.14
1.02
16.3
Norm: MIL 883 E Method 3015
DFN10 3x3mm, T
A
= 70°C
1
W
W
PT Derating Factor
2
WL-CSP 2x1.5mm, T
A
= 70°C
1
DFN10 3x3mm
mW/
°C
14.7
150
mW/
°C
°C
WL-CSP 2x1.5mm
Junction Temperature
260
°C
according to IPC/JEDEC J-
STD-020
Min
3.0
2.6
Typ
3.6
Max
5.5
Unit
V
V
Note
Supply voltage range
AS3685 functionally working,
but not all parameters fulfilled
Depending on load current
and charge pump mode
Limited lifetime, max 20,000s
Mode setting=off;
VBAT<=4.2V
0.4
2.0
-30
25
1.0
85
4.0
A
A
°C
μA
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AS3685C
Datasheet
Table
2 – Operating Conditions
Symbol
I
OPERATING
Parameter
Power Consumption without
load
Min
Typ
0.85
6.6
8.1
Max
Unit
mA
mA
mA
Note
1:1 Mode
1:1.5 Mode
1:2 Mode
5.3 Electrical Characteristics
Table
3 – Charge Pump Characteristics
Symbol
Parameter
V(VCP) Output voltage
without load – do not short to
VSS
Output limitation
Min
Typ
Max
V
BAT
*
CP-
mode
Unit
V
Note
V
CPOUT
CP-mode is 1, 1.5 or 2
(automatically selected)
internally limited
R
CP
Charge Pump effective
Resistance
Eta
V
RIPPLE
fclk
t
UP_DEB_LONG
t
UP_DEB
Output ripple voltage
Operating Frequency
Initial Mode Switching
Debounce Time
Mode Switching Debounce
Time
Table
4 – Current Source (Sink) Characteristics
Symbol
I
LED
Parameter
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Output Current Range
-10%
I
ACCURACY
I
INDICATOR
V
ISET
I
ISET
Current Setting Accuracy
Indicator Current setting
Current Generator Set Point
Voltage (pin ISET)
10.0
Te
Current Generator operating
range
I
FLASH2ISET
V
SWITCH
Flash Current to Bias Current
Ratio
Mode Switching Threshold on
V(ILED) between 1:1 -> 1:1.5
and 1:1.5 -> 1:2
350
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5.4
5.6
0.28
1.37
0.53
2.00
Ω
Ω
1.95
2.44
93
Ω
1:2 Mode
V
BAT
= 3.0V, I
CPOUT
=700mA,
T
JUNCTION
<=85°C
Vin=3.0V-4.5V, Iout=100mA
(Charge Pump alone)
Vin=3.0-4.5V, Iout=350mA,
Efficiency
75
%
100
1.0
mVpp
MHz
μs
-20%
+20%
256
16
μs
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
Min
Typ
700
500
1.0
1.3
130
7650
400
450
Max
Unit
mA
mA
mA
V
μA
A/A
mV
I
ISET
= V
ISET
/ R
ISET
if the resulting bias current is
higher than 200μA (typ.), the
current source is disabled
At full flash current
(700mA with R
ISET
= 14.2kΩ)
Note
1000
+10%
700mA: R
ISET
= 14.2kΩ
1000mA: R
ISET
= 10kΩ
1.1
1:1 Mode
V
BAT
= 3.6V, I
CPOUT
= 200mA
1:1.5 Mode
V
BAT
= 3.3V, I
CPOUT
= 500mA,
T
JUNCTION
<=85°C
Measured with R
ISET
= 19.9kΩ
and maximum flash current
Data1<7:0>(flash LED current)
>= 0x80h in flash mode;
I
LED
>350mA @ R
ISET
=14.2kΩ
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