PRODUCT SUMMARY
SKY81298: 2.4 A Three-Channel Flash LED Driver
with I2C Control Interface
Applications
Description
The SKY81298 is a high-efficiency, high-current boost converter
with three independently programmable constant current outputs.
The device is optimized for LED flash applications implementing
tri-tone flash LED color compensation, or dual rear LED flash plus
single front LED flash to support “selfie” pictures taken from the
front-facing camera. The SKY81298 uses a single DC/DC boost
and only one inductor to support all three LED outputs, and all
LED outputs may be enabled simultaneously to support up to a
total of 2.4 A total LED current.
LED photo flash with Movie/Torch mode
Tri/dual tone LED for color compensation
“Selfie” flash for front-facing camera (PIP enabled)
Smartphones/tablets
Features
Input voltage range: 2.5 V to 5.5 V
The SKY81298 maintains the flash LED output current using a
DC-DC step-up converter with a bypass function to maximize
efficiency under all load conditions. The flash current for each
channel can be programmed up to 1.5 A at 12 mA step. The
device uses a common cathode (current source) topology to allow
a direct flash LED cathode connection to the ground plane which
facilitates LED heat dissipation. The total combined output current
for flash outputs is 2.4 A.
Each channel can program up to 1.5 A with 12 mA step size;
up to 2.4 A total combined output current
> 90% LED efficiency at 250 mA (3.3 V < VIN < 3.6 V,
VF = 3.3 V);
> 85% LED efficiency at 1 A (3.4 V< VIN < 3.9 V, VF = 3.3 V)
2.75 MHz switching frequency
Soft-start and input current limit
Separate flash enable/flash inhibit
Programmable blinking LED notification
Industry standard 1 MHz I2C programming
Flash and Movie mode current
Input voltage monitor with programmable thresholds
Current read-back in input voltage monitor operation
Programmable safety timer
The high-frequency 2.75 MHz DC-DC boost switching frequency
allows the use of a small external inductor and output capacitor,
which makes the SKY81298 ideally suited for small battery-
powered applications. A startup control circuit automatically
senses the flash LED forward voltage at any programmed output
current setting and determines the most efficient operation mode.
An industry standard I2C digital interface is used to program the
SKY81298 LED Flash and Movie modes. Device operations are
fully configurable; Movie and Flash current level, current limits,
and fault reporting are managed through I2C. Also included are
separate flash enable inputs to initiate the flash operation and a
flash inhibit input either to reduce the flash current to Movie-
mode levels or to shut off the flash current during high battery
demand conditions. The flash enable inputs can be configured to
control different flash LEDs as required by the system designer.
Fault read back
Fault protection
Integrated safety timer
Over-voltage (open LED, open circuit)
Short circuit
Over-temperature protection
Flash mode input voltage monitor
Open-drain fault output
The SKY81298 is available in a small 1.903 1.903 0.605 mm,
16-bump Wafer-Level Chip Scale (WLCSP) package.
Temperature range: −40 C to +85 C
Small WLCSP (16-bump, 1.903 1.903 0.605 mm, 0.4 mm
pitch) package (MSL1, 260 C per JEDEC J-STD-020)
The typical application circuits are shown in Figures 1a and 1b.
Skyworks GreenTM products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of GreenTM, document number
SQ04–0074.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
203693A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • August 31, 2015
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