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PDF AS3649 Data sheet ( Hoja de datos )
| Número de pieza | AS3649 | |
| Descripción | 2500mA High Current LED Flash Driver | |
| Fabricantes | ams | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AS3649 (archivo pdf) en la parte inferior de esta página. Total 30 Páginas | ||
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AS3649
2500mA High Current LED Flash Driver
1 General Description
The AS3649 is an inductive high efficient DCDC step up converter
with two current sources. 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 sources
can operate in flash / torch or video light modes.
The AS3649 includes flash timeout, overvoltage, overtemperature,
undervoltage and LED short/open circuit protection functions. A
TXMASK/TORCH function reduces the flash current in case of
parallel operation to the RF power amplifier and avoids a system
shutdown. Alternatively this pin can be used to directly operate the
torch light directly. If the TXMask function is not used, it can be used
as a hardware torch input (programmable).
A hardware NTC pin can be used to measure the LED temperature
with the ADC and to automatically reduce the LED current if a
temperature threshold is exceeded.
The AS3649 is controlled by an I2C interface and has a hardware
reset pin ON. Setting ON=0 resets the AS3649. Interface input
voltage levels are 1.8V compliant.
The AS3649 is available in a space-saving WL-CSP package
measuring only 2.06x2.02x0.6mm and operates over the -30ºC to
+85ºC temperature range.
Figure 1. Typical Operating Circuit
2 Key Features
High efficiency 4MHz fixed frequency DCDC Boost converter
with soft start allows small coils
- Stable even in coil current limit
LED current adjustable up to 2x1000mA(2x1250mA with current
boost) or 2000mA and automatic load balancing for two LEDs
Automatic current adjustment for low battery voltage
PWM operation for lower output current for reliable light output
of the LED; can run at 31.5kHz to avoid audible noise
Protection functions:
Automatic Flash Timeout timer to protect the LED(s)
Overvoltage and undervoltage Protection
Overtemperature Protection
LED short/open circuit protection
ADC to measure LED temperature
NTC to automatically reduce the flash current if the LED
temperature is too high (programmable level)
I2C Interface with hardware reset pin
Available in tiny WL-CSP Package, 16 balls 0.5mm pitch,
2.06x2.02x0.6mm package size
3 Applications
Flash/Torch for mobile phones
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www.ams.com/AS3649
1.0-2
1 - 39
1 page  
AS3649
Datasheet - Electrical Characteristics
6 Electrical Characteristics
VVIN = +2.7V to +4.4V, TAMB = -30ºC to +85ºC, unless otherwise specified. Typical values are at VVIN = +3.7V, TAMB = +25ºC, unless otherwise
specified.
Table 3. Electrical Characteristics
Symbol
Parameter
General Operating Conditions
Condition
Min Typ Max Unit
VVIN Supply Voltage
Pin VIN
2.7 3.7 4.4
V
VVINREDUCED_
FUNC
Supply Voltage
AS3649 functionally working, but not all parameters
fulfilled
2.5
4.4
2.7
V
5.5
ISHUTDOWN
Shutdown Current
TXMASK/TORCH=L, STROBE=L, ON=L, VVIN<3.7V
1.0 2.0 µA
ISTANBY
Standby Current
Interface active, TXMASK/TORCH=L, STROBE=L
VVIN<3.7V
1.0 10 µA
TAMB
Operating Temperature
-30 25 85 ºC
1
Application Efficiency LCOIL=0.6µH@3A, LESR=60m, LED_OUT1,2=2000mA,
(DCDC and current source)
tFLASH<300ms, VFLED=3.7V
83
%
tFLASH
Flash Duration
DCDC Step Up Converter
VVIN>3.3V, TAMB<85ºC, ILED_OUT<2000mA
If TAMB or ILED_OUT is reduced or VVIN is increased,
longer flash times are allowed.
For longer flash durations, see section Current Reduction
by VIN Measurements in Flash Mode and Diagnostic
Pulse on page 15
300 ms
VVOUT
DCDC Boost output
Voltage
(pin VOUT1/2)
2.8 5.5 V
RPMOS
RNMOS
On-resistance
On-resistance
DCDC internal PMOS switch
DCDC internal NMOS switch
45 m
47 m
fCLK
Operating Frequency
All internal timings are derived from this oscillator
-7.5% 4.0 +7.5% MHz
VVOUT5V
DCDC Boost output
Voltage
(pin VOUT1/2)
Constant voltage mode operation const_v_mode (see
page 30)=1
5.0
V
Current Sources
VLED
LED forward voltage
Two flash LEDs, ILED_OUT<2x1000mA
Single flash LED, ILED_OUT<1800mA
2.8 3.32 4.0
2.8 3.32 4.4
V
V
ILED_OUT
LED_OUT1/2 current
combined
VVIN>3.3V, coil_peak=11b,
coil SPM3012T-1R0M,
tFLASH<300ms
dual flash LED,
current_boost=0
single flash LED
0
0
2000 mA
2000 mA
ILED_OUT_BO
OST
ILED_OUT
LED_OUT1/2 current
combined
LED_OUT1/2 current
source accuracy
ILED_OUT
RAMP
LED_OUT1/2 ramp time
ILED_OUT
RIPPLE
LED_OUT current ripple
Dual flash LED, current_boost=1
Otherwise
ILED_OUT=500mA...800mA, 0ºC<TJ<100ºC
Rampup initiated by I2C command
Rampup started by STROBE
Full range Ramp-down
ILED_OUT = 1000mA
0 25002 mA
-7 +7 %
-5 +5 %
730 µs
530 µs
500 µs
40 mAPP
www.ams.com/AS3649
1.0-2
5 - 39
5 Page 
AS3649
Datasheet - Detailed Description
8 Detailed Description
The AS3649 is a high performance DCDC step up converter with internal PMOS and NMOS switches. Its output is connected to one or two flash
LEDs1 with two internal current sources and hardware LED temperature protection using an external NTC. The device is controlled by the pins
SDA and SCL in I2C mode and includes a hardware reset input ON.
The actual operating mode like standby, torch light, indicator or flash mode, can then be chosen by the interface. If not in standby mode, the
device automatically enters shutdown and resets all registers by setting pin ON=0.
The AS3649 includes a fixed frequency DCDC step-up with accurate startup control. Together with the current source (on LED_OUT1/2) it
includes several protection and safety functions.
8.1 Internal Circuit Diagram
Figure 16. Internal Circuit Diagram
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8.2 Softstart / Soft ramp down
During startup and ramp down the LED current is smoothly ramped up and ramped down. If the DCDC converter goes out of regulation
(measured by monitoring the voltage across the current sources), the ramp up is temporarily stopped in order for the DCDC to return to
regulation2.
1. If two LEDs are connected, it is possible to operate each of the two LEDs individually as the LED current can be
selected individually.
2. The actual value of the LED current setting can be readout by the register led_current_actual (see page 31) to allow
the camera processor to adopt to the actual operating conditions.
www.ams.com/AS3649
1.0-2
11 - 39
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet AS3649.PDF ] | |
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