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Datasheet
AS3648
2000mA High Current LED Flash Driver
1 General Description
The AS3648 is an inductive high efficient DCDC step up
converter with two current sinks. The DCDC step up
converter operates at a fixed frequency of 4MHz and
includes soft startup to allow easy integration into noise
sensitive RF systems. The two current sinks can oper-
ate in flash / torch / assist (=video) light modes.
The AS3648 includes flash timeout, overvoltage, over-
temperature, undervoltage and LED short circuit protec-
tion functions. A TXMASK/TORCH function reduces the
flash current in case of parallel operation to the RF
power amplifier and avoids a system shutdown. Alterna-
tively this pin can be used to directly operate the torch
light directly.
2
2 Key Features
High
- Stable even in coil current limit
LED current adjustable up to 2000mA
Two
LED operation or single LED operation (com-
bine LED_OUT1 with LED_OUT2)
The AS3648 is controlled by an I C interface and has a
hardware automatic shutdown if SCL=0 for 100ms.
Therefore no additional enable input is required for shut-
ting down of the device once the system shuts down.
The AS3648 is available in a space-saving WL-CSP
package measuring only 2.25x1.5x0.6mm and operates
over the -30ºC to +85ºC temperature range.
Figure 1. Typical Operating Circuit
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AS3648
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PWM
Protection
I
2
Automatic
current adjustment for low battery voltage
operation for lower output current for reliable
light output of the LED; running at 31.25kHz to avoid
audible noise
functions:
Automatic Flash Timeout timer to protect the LED(s)
Overvoltage and undervoltage Protection
Overtemperature Protection
LED short/open circuit protection
C Interface with automatic shutdown
constant voltage mode operation
5V
Available
in tiny WL-CSP Package, 13 balls 0.5mm
pitch 2.25x1.5x0.6mm, package size
3 Applications
Flash/torch/videolight for smartphones, feature-phones,
tablets, DSCs, DVCs
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AS3648
Datasheet, Confidential - P i n o u t
4 Pinout
Pin Assignment
Figure 2. Pin Assignments (Top View)
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Pin Description
Pin Number
A1
A2
A3
B1
B2
C1
C2
C3
Table 1. Pin Description for AS3648
Pin Name
VOUT1
GND
SW1
LED_OUT1
GND
SW2
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LED_OUT2
SCL
VIN
D1
D2
E1
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E2
STROBE
E3
TXMASK/
TORCH
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AS3648
Description
DCDC converter output capacitor - make a short connection to C
VOUT
/ VOUT2
Power and analog ground; make a short connection between both balls
Flash LED current sink
DCDC converter switching node - make a short connection to SW2 / coil L
DCDC
DCDC converter output capacitor - make a short connection to C
VOUT
/ VOUT1
Power and analog ground; make a short connection between both balls
VOUT2
DCDC converter switching node - make a short connection to SW1 /coil L
DCDC
Flash LED current sink
serial clock input for I C interface
2
Positive supply voltage input - connect to supply and make a short connection
to input capacitor C
VIN
and to coil L
DCDC
2
SDA
serial data input/output for I C interface (needs external pullup resistor)
Digital input with pulldown to control strobe time for flash function
Function 1: Connect to RF power amplifier enable signal - reduces currents
during flash to avoid a system shutdown due to parallel operation of the RF PA
and the flash driver
Function 2: Operate torch current level without using the I C interface to
operate the torch without need to start a camera processor (if the I C is
connected to the camera processor
2
2
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AS3648
Datasheet, Confidential - A b s o l u t e M a x i m u m R a t i n g s
5 Absolute Maximum Ratings
Stresses beyond those listed in
Table 3
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
Table 4, “Electrical
Characteristics,” on page 4
is not implied. Exposure to absolute maximum rating conditions for extended periods may
affect device reliability.
Table 3. Absolute Maximum Ratings
VIN to GND
STROBE, TXMASK/TORCH, SCL, SDA to
GND
SW1/2, VOUT1/2, LED_OUT1/2 to GND
VOUT1/2 to SW1/2
-0.3
-0.3
-0.3
-0.3
0.0
+7.0
VIN +
0.3
+7.0
V
V
V
V
max. +7V
voltage between GND pins
Input Pin Current without causing latchup
Continuous Power Dissipation (T
A
= +70ºC)
Continuous power dissipation
Continuous power dissipation derating factor
Electrostatic Discharge
ESD HBM
3
pins LED_OUT1/2
ESD HBM
ESD MM
ESD CDM
Temperature Ranges and Storage Conditions
Junction to ambient thermal resistance
Junction Temperature
Storage Temperature Range
Humidity
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Body Temperature during Soldering
Moisture Sensitivity Level (MSL)
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1. Depending on actual PCB layout and PCB used measured on demoboard; for peak power dissipation during
flashing see document 'AS3648 Thermal Measurements'
2. P
DERATE
derating factor changes the total continuous power dissipation (P
T
) if the ambient temperature is not
70ºC. Therefore for e.g. T
AMB
=85ºC calculate P
T
at 85ºC = P
T
- P
DERATE
* (85ºC - 70ºC)
3. Pins LED_OUT1 connected to LED_OUT2 and capacitor C
VOUT
connected to VOUT1/2 and GND; both GND
pins connected together
4. Measured on AS3648 Demoboard.
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0.0
V
short connection recommended
Norm: EIA/JESD78
-100
+100
+I
IN
1230
16.7
mA
mW
P
T
at 70ºC
P
DERATE
2
1
Note:
Diode between VOUT1/2 and
SW1/2
mW/ºC
±8000
±2000
±500
±100
V
V
Norm: JEDEC JESD22-A114F
V
Norm: JEDEC JESD 22-C101E
V
Norm: JEDEC JESD 22-A115-B
60
4
ºC/W
ºC
For more information about thermal
metrics, see application note AN01
Thermal Characteristics
Internally limited (overtemperature
protection), max. 20000s
Non condensing
+150
-55
5
+125
85
ºC
%
+260
MSL 1
ºC
according to IPC/JEDEC J-STD-020
Represents a max. floor life time of
unlimited
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Parameter
Min
Max
Units
Comments
AS3648
Datasheet, Confidential - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
V
VIN
= +2.7V to +4.4V, T
AMB
= -30ºC to +85ºC, unless otherwise specified. Typical values are at V
VIN
= +3.7V, T
AMB
=
+25ºC, unless otherwise specified.
Table 4. Electrical Characteristics
Symbol
V
VIN
V
VINREDUCE
D_FUNC
Parameter
Supply Voltage
Supply Voltage
Shutdown Current
Standby Current
Operating
Temperature
Condition
pin VIN
AS3648 functionally working, but not all
parameters fulfilled
TXMASK/TORCH=L, SCL=SDA=0V,
V
VIN
<3.7V
interface active, TXMASK/TORCH=L,
1
V
VIN
<3.7V
Min
2.7
2.5
4.4
Typ
3.7
Max
4.4
Unit
V
General Operating Conditions
I
SHUTDOWN
I
STANBY
T
AMB
Eta
0.6
1.0
25
Application Efficiency
(DCDC and current
sink)
DCDC Boost output
Voltage
(pin VOUT1/2)
DCDC Boost output
Voltage
(pin VOUT1/2)
On-resistance
On-resistance
DCDC Step Up Converter
V
VOUT
V
VOUT5V
R
PMOS
R
NMOS
f
CLK
Operating Frequency
Current Sinks
V
LED
LED forward voltage
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I
LED_OUT
LED_OUT1/2 current
sinks output combined
I
LED_OUT
I
LED_OUT
RAMP
LED_OUT1/2 current
sink accuracy
LED_OUT1/2 ramp
time
LED_OUT current
ripple
LED_OUT current
sink voltage
compliance
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I
LED_OUT
RIPPLE
V
ILED_COMP
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10
µA
ºC
%
-30
85
L
COIL
=0.6µH@3A, L
ESR
=60m,
2
LED_OUT1,2=1300mA , t
FLASH
<300ms
84
2.8
5.5
V
constant voltage mode operation
const_v_mode (see page 25)=1
DCDC internal PMOS switch
5.0
70
V
DCDC internal NMOS switch
70
All internal timings are derived from this
oscillator
two flash LEDs at 1800mA combined
single flash LED at 1600mA
-7.5%
4.0
+7.5%
2.8
3.5
3.95
4.2
V
2.8
0
V
dual flash LED
current_boost=1
2000
3
current_boost=0
0
single flash LED
I
LED_OUT
>=800mA or I
LED_OUT
<500mA
0ºC < T
J
< 100ºC
Ramp-up During startup
Ramp-down
I
LED_OUT
= 1000mA, BW=20MHz
-7
-5
250
500
20
325
360
500mA<I
LED_OUT
<800mA, 0ºC < T
J
< 100ºC
Minimum voltage between
pin LED_OUT1/2 and GND
for operation of the current
sink
current_boost=0
current_boost=1
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5.5
V
2.0
µA
m
m
MHz
1800
1600
+7
+5
1000
1000
mA
mA
%
%
µs
µs
mA
PP
mV
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