DATA SHEET
SKY81290: 1.2 A Single Flash LED Driver With AS2C Interface
Applications
Description
LED photo flash/torch devices
The SKY81290 is a high-efficiency, 1.2 A high current boost
converter with a programmable constant current sink. It is an
ideal power solution for LED photo flash applications in all single
cell, Li-ion powered products.
Camera-enabled mobile devices
Cellphones/smartphones
Multimedia mobile phones
Features
Input voltage range: 2.7 V to 5.5 V
Single channel flash output
Up to 1.2 A regulated output current
Up to 88% efficiency
Switching frequency: 2.0 MHz
Separate flash enable
Single resistor sets Flash and Movie Mode current
Flash safety timer
AS Cwire single wire programming:
Movie Mode current
Flash/Movie Mode current ratio
Maximum flash current ratio
2
True Load Disconnect
Soft start and input current limit
Over voltage (open LED, open circuit), short circuit, and
over-temperature protection
TDFN (14-pin, 3 x 3 mm and 3 x 2 mm) packages (MSL1,
260 C per JEDEC J-STD-020)
Skyworks Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of Green™, document number
SQ04-0074.
The SKY81290 maintains output current regulation by switching
the internal high-side and low-side switch transistors. The
transistor switches are pulse-width modulated at a fixed
frequency of 2.0 MHz. The high switching frequency allows the
use of a small external inductor and output capacitor, which
makes the SKY81290 ideally suited for small battery-powered
applications.
Skyworks proprietary Advanced Simple Serial Control
(AS2Cwire™) digital interface is used to enable, disable, configure,
and program the operation of the SKY81290. Using the AS2Cwire
interface, the Movie Mode current level for each LED, flash safety
timer, and the flash-to-Movie-Mode current ratio can be
programmed to one of 16 levels.
The SKY81290 includes a separate flash enable input (FLEN) to
initiate the flash operation. Also included is a flash inhibit pin
(FLINH) that reduces the flash current to Movie Mode levels during
high battery demand. The maximum Flash and Movie Mode
current is set by one external resistor where the ratio of Flash to
Movie Mode current is set at approximately 7:1.
The SKY81290 contains a thermal management system to protect
the device in the event of an output short-circuit condition. Builtin circuitry prevents excessive inrush current during start-up. The
shutdown feature reduces quiescent current to less than 1.0 μA.
The SKY81290 is available in a 14-pin, 3 x 3 mm TDFN package
and a 14-pin, 3 x 2 mm TDFN package. A typical application
circuit is shown in Figure 1. The pin configuration and packages
are shown in Figure 2. Signal pin assignments and functional pin
descriptions are provided in Table 1.
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DATA SHEET • SKY81290 1.2: A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
L1
1 μH
SW
OUT
IN
VBATT = 2.9 V to 5.5 V
COUT
2.2 μF
CIN
2.2 μF
Flash LED
SKY81290
Enable/Set Input
EN / SET
Flash Enable
FL
FLEN
RSET
RSET
Flash Inhibit
FLINH
PGND AGND
FLGND
S3419
Figure 1. Typical Application Circuit
N/C
1
14
RSET
EN/SET
2
13
FL
FLEN
3
12
AGND
4
IN
N/C
1
14
RSET
EN/SET
2
13
FL
FLGND
FLEN
3
12
FLGND
11
N/C
AGND
4
11
N/C
5
10
FLINH
IN
5
10
FLINH
SW
6
9
AGND
SW
6
9
AGND
PGND
7
8
OUT
PGND
7
8
OUT
3x3 mm TDFN
3x2 mm TDFN
S3267
Figure 2. SKY81290 Pinout – 14-Pin TDFN Packages
(Top View)
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DATA SHEET • SKY81290: 1.2 A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Table 1. SKY81290 Signal Descriptions
Pin
Name
Description
Pin
Name
Description
1
N/C
No connect.
8
OUT
Power output of the boost converter. Connect a 10 V,
X7R 2.2 μF or larger ceramic capacitor from OUT to
PGND, and locate as close to the device as possible.
Connect OUT to the anode of the flash LED.
2
EN/SET
Enable and serial control input. This pin is the AS2Cwire
addressing and programming input to adjust the Movie
Mode current level, select the Flash-to-Movie-Mode
ratio, and set the flash safety timer. This pin has an
internal 675 kΩ pull-down resistor.
9
AGND
Analog ground pin. Connect AGND to PGND and FLGND
at a single point as close to the device as possible.
3
FLEN
Flash enable pin. A low-to-high transition on this pin
initiates a flash pulse and a high-to-low transition
terminates a flash pulse. This pin has an internal 225 kΩ
pull-down resistor.
10
FLINH
Flash inhibit pin. FLINH is an active high control input
with an internal 225 kΩ resistor to AGND. A low-to-high
transition on the FLINH pin reduces FL pin sink current to
the maximum (default) Movie Mode current level.
4
AGND
Analog ground pin. Connect AGND to PGND and FLGND
at a single point as close to the device as possible.
11
N/C
No connect.
5
IN
Flash output boost converter power input. Connect IN to
the input power source. Connect a 10 V, X7R 2.2 μF or
larger ceramic capacitor from IN to PGND, and locate as
close to the device as possible for optimum
performance.
12
FLGND
Flash ground pin. Connect FLGND to PGND and AGND at
a single point as close to the device as possible.
6
SW
Boost converter switching node. Connect a 1 μH
inductor between the SW and IN pins.
13
FL
LED flash current sink pin. Connect the cathode of the
flash LED to this pin.
7
PGND
14
RSET
Flash current set pin. Connect a resistor from RSET to
AGND to program the desired flash current for the
current sink pin (FL).
Power ground. Connect PGND to the same single point
as AGND and located as close to the device as possible.
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DATA SHEET • SKY81290 1.2: A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Table 2. SKY81290 Absolute Maximum Ratings
Parameter
Symbol
Maximum voltage rating
Minimum
Maximum
Units
IN, OUT, SW
–0.3
+6.0
V
EN/SET, FLEN,
FLINH, RSET, FL
–0.3
VIN + 0.3
V
Storage temperature
TS
–65
+150
C
Junction operating temperature
TJ
–20
+150
C
+300
C
Soldering temperature (at leads, 10 sec)
TLEAD
Thermal resistance (as mounted on an FR4 board, measured
according to EIA/JESD 51 series):
3 x 3 TDFN
3 x 2 TDFN
ΘJA
Maximum power dissipation @ 25 C:
3 x 3 TDFN
3 x 2 TDFN
PD
Note:
35
41
C/W
C/W
3.29
2.80
W
W
Exposure to maximum rating conditions for extended periods may reduce device reliability. There is no damage to device with only one parameter set at the limit and all other
parameters set at or below their nominal value. Exceeding any of the limits listed here may result in permanent damage to the device.
CAUTION: Although this device is designed to be as robust as possible, electrostatic discharge (ESD) can damage this device. This device
must be protected at all times from ESD. Static charges may easily produce potentials of several kilovolts on the human body
or equipment, which can discharge without detection. Industry-standard ESD precautions should be used at all times.
Table 3. SKY81290 Recommended Operating Conditions
Parameter
Symbol
Minimum
Typical
Maximum
Units
Input voltage
VIN
2.7
5.5
V
Operating temperature
TOP
–40
+85
C
Electrical and Mechanical Specifications
The absolute maximum ratings of the SKY81290 are provided in
Table 2. Recommended operating conditions are specified in
Table 3. Electrical specifications are provided in Table 4.
Typical performance characteristics of the SKY81290 are
illustrated in Figures 3 to 19.
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DATA SHEET • SKY81290: 1.2 A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Table 4. SKY81290 Electrical Specifications (Note 1)
(VIN = 3.6 V, CIN = COUT = 2.2 μF, RSET = 162 kΩ, L = 1 μH, TA = –40 C to +85 C [Typical Values are TA = +25 C],
Unless Otherwise Noted)
Parameter
Symbol
Test Condition
Min
Typical
Max
Units
5.5
V
Power Supply, Current Sinks
Input voltage range (Note 2)
VIN
Supply current
IIN(Q)
2.7
EN/SET = FLEN = IN,
FL load = 1 A
1.40
EN/SET = IN,
FLEN = AGND
0.23
Input shutdown current
ISHDN
EN/SET and FLEN = AGND
Maximum flash current
IFL(MAX)
RSET = 135 kΩ,
VF = 3.3 V, VIN = 4.2 V
Boost switch current limit
ILIMIT
IFL(ACC)
IFL = 1 A
Total output current, Movie Mode
IMM(LOAD)
Move Mode current set to
100%, IFL = 1 A
Movie Mode current accuracy
IMM(ACC)
Flash to Movie Mode ratio
IFL/IMM
Switching frequency
fOSC
Over-temperature shutdown threshold
TSD
mA
1
1.2
2.8
–8
+8
143
–8
1.5
+8
2.0
A
%
mA
7
TA = 25 °C
μA
A
1.8
Flash current accuracy
mA
%
–
2.5
MHz
C
140
Output over-voltage limitation
VOVP
5.3
V
Open LED, short circuit protection threshold
VFL_FLT
150
mV
Protection delay time
tFLT_DEL
1.4
ms
EN/SET, FLEN, FLINH
Logic threshold:
Low
High
VIL
VIH
Internal pull-down resistance (EN/SET)
REN/SET_PUDN
675
kΩ
Internal pull-down resistance (FLEN, FLINH)
RPUDN
225
kΩ
0.4
1.4
0.3
75
V
V
μs
Serial interface low time (EN/SET)
tEN/SET(LO)
Minimum EN/SET high time
tEN/SET(HI-MIN)
Maximum EN/SET high time
tEN/SET(HI-MAX)
EN/SET off timeout time
EN/SET latch timeout time
FLEN delay time:
On
Off
tFLEN(ON)
tFLEN(OFF)
40
10
μs
μs
FLINH on delay time
tFLENH(ON)
93
μs
50
ns
75
μs
tEN/SET(OFF)
500
μs
tEN/SET(LAT)
500
μs
EN/SET = AGND
Auto Disable Function
Shorted LED detection voltage
VLED(DETECT)
VIN = 3.6 V, ILED = 2.4 mA
1.7
V
Note 1: Performance is guaranteed only under the conditions listed in this table.
Note 2: Flash mode operation may be limited by the boost switch current limit.
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DATA SHEET • SKY81290 1.2: A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Typical Performance Characteristics
(VIN = 3.6 V, CIN = COUT = 2.2 μF, RSET = 162 kΩ, L = 1 μH, TA = –40 C to +85 C [Typical Values are TA = +25 C],
Unless Otherwise Noted)
95
90
IMM = 174 mA
IMM = 142 mA
90
80
Efficiency (%)
Efficiency (%)
85
80
75
70
65
70
60
50
IFL nom = 1.2 A
IFL nom = 1.0 A
IFL nom = 700 mA
IFL nom = 540 mA
60
40
55
50
2.7 2.9
3.1
3.3 3.5
3.7
3.9
4.1 4.3
4.5
4.7
4.9
5.1
5.3
30
5.5
3.2 3.3
3.4
3.5
Input Voltage (V)
3.6
3.7
3.8
3.9
4.0
4.1
4.2
4.3
4.4
Input Voltage (V)
Figure 3. Movie Mode Efficiency vs Input Voltage
Figure 4. Flash Mode Efficiency vs Input Voltage
0
+0.6
+0.4
–0.2
+0.2
Accuracy (%)
Accuracy (%)
–0.4
–0.6
–0.8
–1.0
–1.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
–1.4
–1.2
–1.6
–60
–40
–20
0
+20
+40
+60
+80
–1.4
–60
+100
–40
–20
+20
+40
+60
+1.5
+100
Flash On Time Delay (ms)
30
+1.0
+0.5
0
–0.5
–1.0
25
20
15
10
TA = +85 °C
TA = +25 °C
TA = –40 °C
5
0
–1.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
Input Voltage (V)
Figure 7. Movie Mode Current Accuracy vs Input Voltage
(IMM = 142 mA, L = 1 μH)
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
Input Voltage (V)
Figure 8. Flash On Time Delay vs Input Voltage
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+80
Figure 6. Movie Mode Current Accuracy vs Temperature
(IMM = 142 mA, VIN = 3.6 V, L = 1 μH)
Figure 5. Flash Mode Current Accuracy vs Temperature
(IFL = 1 A, VIN = 3.6 V, L = 1 μH)
Accuracy (%)
0
Temperature (°C)
Temperature (°C)
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DATA SHEET • SKY81290: 1.2 A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
80
EN/SET Latch Timeout (ms)
EN/SET Off Timeout (ms)
70
60
50
40
30
TA = +85 °C
TA = +25 °C
TA = –40 °C
20
10
0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
70
60
50
40
30
TA = +85 °C
TA = +25 °C
TA = –40 °C
20
10
0
2.7
5.5
3.1
3.5
1.4
4.7
5.1
5.5
1.2
1.0
0.8
0.6
TA = +85 °C
TA = +25 °C
TA = –40 °C
0.4
0.2
1.4
1.2
1.0
0.8
0.6
TA = +85 °C
TA = +25 °C
TA = –40 °C
0.4
0.2
0
3.1
3.5
3.9
4.3
4.7
5.1
5.5
2.7
3.1
3.5
Input Voltage (V)
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Figure 11. EN/SET, FLEN Low Threshold Voltage vs Input Voltage
Figure 12. EN/SET, FLEN High Threshold Voltage vs Input Voltage
3.0
2.16
2.14
Supply Current (mA)
Boost Switching Frequency (MHz)
4.3
Figure 10. EN/SET Latch Timout vs Input Voltage
EN/SET, FLEN High Threshold
Voltage (V)
EN/SET, FLEN Low Threshold
Voltage (V)
Figure 9. EN/SET Off Timeout vs Input Voltage
0
2.7
3.9
Input Voltage (V)
Input Voltage (V)
2.10
2.10
2.08
2.06
2.04
2.02
2.5
2.0
1.5
1.0
0.5
2.00
1.98
2.7
3.1
3.5
3.9
4.3
4.7
5.1
Input Voltage (V)
Figure 13. Boost Switching Frequency vs Input Voltage
(TA = 25 °C, L = 1 μH)
5.5
0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Figure 14. Supply Current vs Input Voltage
(VEN/SET = VFLEN = VIN, IFL = 0 mA, Non-Switching)
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DATA SHEET • SKY81290 1.2: A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
VSW
(2 V/div)
VSW
(2 V/div)
VOUT
(10 mV/div)
VOUT
(50 mV/div)
ISW
(100 mA/div)
ISW
(1 A/div)
Time (400 ns/div)
Time (400 ns/div)
Figure 15. Movie Mode Ripple
(IMM = 142 mA, COUT = 2.2 μF, VIN = 3.6 V, L = 1 μH)
Figure 16. Flash Mode Ripple
(IFL = 1 A, COUT = 2.2 μF, VIN = 3.6 V, L = 1 μH)
VFLEN
(4 V/div)
VFLEN
(4 V/div)
VOUT
(2 V/div)
VOUT
(2 V/div)
VSINK
(2 V/div)
VSINK
(1 V/div)
IFL
(1 A/div)
IFL
(1 A/div)
Time (100 µs/div)
Figure 17. Flash Turn On
(VOUT = 3.6 V, IFL = 1 A)
Time (100 µs/div)
Figure 18. Movie Mode to Flash Turn On
(VOUT = 3.6 V, IFL = 174 mA to 1.2 A)
VEN/SET
(5 V/div)
VOUT
(2 V/div)
VSINK
(2 V/div)
IFL
(100 mA/div)
Time (200 µs/div)
Figure 19. Movie Mode Turn On
(VOUT = 3.6 V, IFL = 142 mA)
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DATA SHEET • SKY81290: 1.2 A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
SW
OUT (to Flash LED)
FL
IN
EN/SET
FLEN
System Control Enable
and AS2C Interface
FLGND
RSET
FLINH
AGND
PGND
S3170
Figure 20. SKY81290 Functional Block Diagram
Functional Description
Move (Torch) Mode
The SKY81290 is a boost converter with a current-regulated
output designed to drive high current, white LEDs used in camera
flash applications. The SKY81290 has a constant current sink
channel to accurately regulate the current flow through a high
current, high intensity white flash LED.
The Movie (Torch) Mode current level is programmed by the
SKY81290 AS2Cwire interface using the EN/SET pin. The Movie
Mode current level can be adjusted to one of 16 steps using a
logarithmic scale where each code level is 1 dB below the
previous code. The maximum Movie Mode current is fixed at 1/7th
of the maximum programmed flash current set by the RSET
resistor. The manual FLEN signal has priority over Movie Mode
operation.
The SKY81290 has two basic operating modes: a Flash Mode
controlled by the FLEN pin, and a Movie/Torch Mode controlled
through the AS2Cwire interface.
A functional block diagram is shown in Figure 20.
Flash Mode
A flash pulse is initiated by strobing the FLEN input pin low-tohigh. The maximum flash current in the SKY81290 is set by an
external resistor (RSET) that sets the flash current and the
maximum Movie Mode current. The maximum flash current is
limited by the boost switch current limit.
For mobile GSM systems where the phone remains in constant
contact with the base station by regular communication, a FLINH
pin is provided to prevent both the camera flash and PA
transmission pulses from occurring simultaneously. This avoids
potential dips to the Li-ion battery voltage below the system’s cut
off voltage.
During a flash event, strobing the FLINH pin low-to-high reduces
the LED current to the default Movie Mode current level for the
duration of FLINH. Strobing FLINH high-to-low instructs the
SKY81290 to revert the flash LED current to its maximum level,
assuming that the FLEN pin is still active (high).
The FLEN signal overrides the Movie Mode operation when
toggled to a logic high level. The SKY81290 does not reenter
Movie Mode when FLEN is brought low. To reenter Movie Mode
after a flash event, the device must be cycled off and back on to
reset the Movie Mode and reprogrammed with the AS2Cwire
interface to the desired Movie Mode operation.
Open LED or Short Circuit Protection
The SKY81290 features open LED protection and short circuit
protection. When the FL pin voltage drops below 150 mV, the
boost output reaches the overprotection level (typically 5.3 V).
After the output voltage reaches the overprotection level, if the FL
voltage is kept below 150 mV for more than 1.4 msec (typical),
the SKY81290 triggers the open LED/short circuit protection and
latches off the device. The output is also disconnected from the
input supply. To restart the device requires cycling the input
power or EN pin.
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DATA SHEET • SKY81290 1.2: A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Flash Safety Timer
The SKY81290 is equipped with a flash safety timer that will turn
off the flash according to the programmed safety time in Flash
Mode. The default safety time is set as 1 sec but can be
programmed between 0.25 sec and 1.75 sec. The safety timer
can also be disabled through AS2Cwire programming.
default Movie Mode current level appears at the FL channel. The
default Movie Mode current level is maintained on FL as long as
the FLINH and FLEN pins are asserted.
Besides setting the flash current using the RSET resistor, the flash
current can be changed after FLEN is asserted by programming
the Movie Mode current register.
Short LED Protection
AS2Cwire Control of Movie Mode Operation
The SKY81290 is equipped with an auto-disable feature for the
flash LED channel. After the device is enabled and system start up
commences, a test current of 2.4 mA (typical) is forced through
the sink channel. The channel is disabled if the voltage of the FL
pin does not drop to a predetermined threshold (1.7 V minimum).
Movie Mode operation is managed by programming the AS2Cwire
interface. This interface relies on the number of rising edges of
the EN/SET pin to address and load internal data registers as
indicated in Table 5.
This feature is very convenient for disabling the current sink when
the flash LED fails to a short circuit. This small test current is
added to the set output current in both Flash and Movie Mode
conditions.
Register 0 controls the Movie Mode current level as a percentage
of the maximum Movie Mode current. Table 5 also shows the
default values for each of the address registers.
AS2Cwire Serial Interface
Over-Temperature Protection
The SKY1290 has internal thermal protection circuitry to latch off
the device if the internal power dissipation exceeds a preset
thermal limit for over 1.4 ms. The junction over-temperature
threshold is 140 °C. During Flash or Movie Mode operation, if an
environmental condition, flash current sink, or the boost converter
causes the internal die temperature to rise above 140 °C, the
device latches off and disconnects the output from the input
circuit.
Flash Mode LED Current
Flash sink current can be programmed up to a maximum of 1.2 A.
The maximum flash current is set by the RSET resistor. For the
desired flash current, the resistor value can be calculated using
the following equation:
I FL
162 k A 162 k
1.2 A
RSET
135 k
The AS2Cwire interface latches data or an address after the
EN/SET pin has been held high for longer than tLAT (500 μs).
Address or data are differentiated by the number of EN/SET rising
edges. Since the data registers are 4 bits each, the differentiating
number of pulses is 24 or 16, so that Register/address 0 is
signified by 17 rising edges and Register/address 3 by 20 rising
edges (refer to Table 5).
Data in Register/address 0 is inclusively applied to any number of
rising edges between 1 and 16. A typical write protocol is a burst
of EN/SET rising edges that signify a particular address followed
by a pause with EN/SET held high for the prescribed tLAT timeout
period, then a burst of rising edges signifying data, and a tLAT
timeout for the data registers.
Once an address is set, then multiple writes to the corresponding
data register are allowed. Address 0 is the default address on the
first rising edge after the SKY81290 has been disabled.
A flash event is initiated by asserting the FLEN pin. A flash event
is automatically terminated when FLEN is de-asserted or the flash
safety timer expires. Whenever the FLINH pin is asserted, the
Table 5. AS2Cwire Serial Interface Addressing
Register/Address
EN/SET
Rising Edges
Function
Default
(No Programming)
0
17
Movie Mode current
100%
1
18
Flash safety timer time
1 second
2
19
Output enable control
On
3
20
Flash current ratio (Flash/Movie Mode current ratio is fixed at 1:7)
100%
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DATA SHEET • SKY81290: 1.2 A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Address
tLO
Data
tHI
tLAT
tLAT
EN/SET
1
Address
2
16
17
1
2
n ≤ 16
0
Data Register 1
1
0
n
S3090
Figure 21. AS2Cwire Serial Interface Timing Diagram
When EN/SET is transitioned from high to low and held low longer
than tOFF (500 μs), the device enters a shutdown mode and draws
less than 1 μA from the input supply. All data and addresses are
cleared (reset to 0) during shutdown.
AS2Cwire addressing controls the Movie Mode output current and
the ratio of Movie Mode current to flash current. If there are no
programmed write instructions applied to the EN/SET pin before
the assertion of the FLEN pin, and the device is enabled, then all
registers are loaded with the default values shown in Table 5.
If the number of rising edges applied at the EN/SET pin is fewer
than 17, the internal state machine interprets the instruction to
program the output currents to the desired current level for Movie
Mode operation.
A timing diagram for the AS2Cwire interface is shown in Figure 21.
Register 0: Movie Mode Current
The SKY81290 Movie Mode current settings are controlled using
the AS2Cwire interface. The ratio between the flash current level
and maximum Movie Mode current level is fixed at 1:7. For
example, if an RSET value of 135 kΩ is chosen, then the flash
current is set to 1200 mA. For Movie Mode operation, the
maximum current available is then:
IFL(MAX) = 162 kΩ/RSET × 1000 mA
IMOVIEMODE = IFL(MAX)/7 = 1200 mA/7 = 171 mA
Register/address 0 controls precise Movie Mode current levels.
The Movie Mode current can be adjusted in a logarithmic fashion
to one of 16 steps represented as a fraction of the maximum
Movie Mode current as noted in Table 6.
Table 6. Register/Address 0: Movie Mode Current Programming
Data
Percentage of Maximum Movie Mode Current
Data
Percentage of Maximum Movie Mode Current
1 (default)
100.0
9
49.5
2
93.7
10
43.2
3
87.4
11
36.9
4
81.1
12
30.6
5
74.8
13
24.3
6
68.4
14
18.0
7
62.1
15
11.7
8
55.8
16
5.5
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DATA SHEET • SKY81290 1.2: A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Table 7. Register/Address 1: Flash Safety Timer
Data
Flash Safety Timer Time
(seconds)
Data
Flash Safety Timer Time
(seconds)
1
Disables the timer
5 (default)
1.00
2
0.25
6
1.25
3
0.50
7
1.50
4
0.75
8
1.75
Table 8. Register/Address 2: Movie Mode Enable Control
Data
Movie Mode Enable
Data
Movie Mode Enable
1
Off
3
On
2
Off
4 (default)
On
Table 9. Register/Address 3: Flash Current Ratio
Data
Maximum Flash Current Ratio
Data
Maximum Flash Current Ratio
1 (default)
100%
3
70%
2
84%
4
62%
Register 1: Flash Safety Timer
The SKY81290 is equipped with a flash safety timer. This timer
limits the operation time in Flash Mode to thermal issues. The
safety timer can be adjusted from 0.25 seconds to 1.75 seconds
as noted in Table 7.
Register 2: Movie Mode Enable Control
To enable or disable Movie Mode, a write instruction to address 2
is applied to the EN/SET pin (see Table 8). If no write instruction is
applied, the default value for address 2 is “on.” During a flash
event, the LED is enabled regardless of the Movie Mode setting.
Register 3: Flash Current Ratio
During flash start up, the maximum peaked sustained flash
current level is programmable using Register/address 3. This level
is a fraction of the maximum flash current set by RSET. The ratio
can vary from 100 percent to 62 percent in 4 steps as shown in
Table 9.
Shutdown
section enters shutdown mode and draws less than 1 μA from the
input power source. All data and address registers for the Flash
and/or Movie Mode are cleared (reset to 0) during shutdown.
Evaluation Board Description
The SKY81290 Evaluation Board is used to test the performance
of the SKY81290 LED Driver. An Evaluation Board schematic
diagram is provided in Figure 22. Layer details for the Evaluation
Board are shown in Figure 23. Table 10 provides the Bill of
Materials (BOM) for Evaluation Board components.
Package Dimensions
The PCB layout footprint for the SKY81290 is provided in
Figure 24 (3 x 3 TDFN) and Figure 25 (3 x 2 TDFN). Typical case
markings are shown in Figure 26.
Package dimensions, and tape and reel dimensions for the 14pin, 3 x 3 mm TDFN package are shown in Figures 27 and 28,
respectively. Package dimensions, and tape and reel dimensions
for the 14-pin, 3 x 2 mm TDFN package are shown in Figures 29
and 30, respectively.
Since the flash current sink is the only power return for the flash
LED load, there is no leakage current to load if all the sink
switches are disabled. When the EN/SET pin is held low for
greater than tOFF (500 μs), the SKY81290 flash boost converter
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DATA SHEET • SKY81290: 1.2 A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Package and Handling Information
Instructions on the shipping container label regarding exposure to
moisture after the container seal is broken must be followed.
Otherwise, problems related to moisture absorption may occur
when the part is subjected to high temperature during solder
assembly.
additional information, refer to the Skyworks Application Note,
Solder Reflow Information, document number 200164.
Care must be taken when attaching this product, whether it is
done manually or in a production solder reflow environment.
Production quantities of this product are shipped in a standard
tape and reel format.
The SKY81290 is rated to Moisture Sensitivity Level 1 (MSL1) at
260 C. It can be used for lead or lead-free soldering. For
DC +
FLINH
JP6
1 2 3
MCU
R5
R6
R7
10 kΩ 10 kΩ 10 kΩ
SW 1
MMC
2
4
1
3
5
SW 2
Flash Current Ratio
2
4
U2
1
2
3
4
VDD
GP 5
GP 4
GP 3
VSS
GP 0
GP 1
GP 2
8
7
6
5
2
4
FLEN
2
4
1
3
5
2
4
SW 4
SW 5
1
3
5
JP4
2
JP3
2
1
1
R4
100 kΩ
VOUT
R3
100 kΩ
LED 1
RED
D1
LED 2
Green
SW 3
Movie ON /OFF
R10
10 kΩ
R8
330 Ω
R9
330 Ω
PIC 12F 675
1
3
5
C3
1 μF
JP2
0Ω
1
3
5
JP1
0Ω
U1
DC JP5
1 2 3
R2
100 kΩ
EN /SET
C1
2.2 μF
L1
1 μH
1
2
3
4
5
6
7
JP8
FLINH
1
3
5
7
9
N/C
EN /SET
FLEN
AGND
IN
SW
PGND
RSET
FL
FLGND
N/C
FLINH
AGND
OUT
14
13
12
11
10
9
8
R1
162 kΩ
C2
2.2 μF
2
4
6
8
10
S3265
Figure 22. SKY81290 Evaluation Board Schematic
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DATA SHEET • SKY81290 1.2: A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Top Layer
Bottom Layer
Figure 23. SKY81290 Evaluation Board Layer Details
Table 10. SKY81290 Evaluation Board Bill of Materials (BOM)
Component
Description
Manufacturer
Part #
C1, C2
2.2 μF, 10 V, X7R, 0603
Murata
GRM188R71A225KE15
C3
1 μF, 10 V, X5R, 0805
Murata
GRM216R61A105KA01
D1
White flash LED
Seoul Semiconductor
SSC-FCW401Z4
JP3, JP4, JP5, JP6
Connecting header, 2mm zip
Sullins Electronics
PRPN401PAEN
L1
1 μH, 3 A, 45 mΩ, 2.5 mm x 2 mm
TOKO
DFE252012C
LED1
Red LED, 1206
Chicago Miniature Lighting
CMD15-21SRC/TR8
LED2
Green LED, 1206
Chicago Miniature Lighting
CMD15-21VGC/TR8
JP1, JP2
0 Ω, 1%
Vishay
Chip resistor
R1
162 kΩ, 1%, 0402
Vishay
Chip resistor
R2, R3, R4
100 kΩ, 1%, 0603
Vishay
Chip resistor
R5, R6, R7, R10
10 kΩ, 1%, 0603
Vishay
Chip resistor
R8, R9
330 Ω, 1%, 0603
Vishay
Chip resistor
SW1 to SW5
Switches, SPST, 5 mm
ITT Industries
PTS645TL50
U1
1.2 A step-up current regulator for flash LEDs
Skyworks
SKY81290
U2
8-bit CMOS, flash-based I/C (8-pin PDIP package)
Microchip
PIC12F675
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DATA SHEET • SKY81290: 1.2 A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Pin 1 Indicator
0.3 X 45°
3.00
0.40 Pitch
2.55
14X 0.200
14X 0.800
15X Exposed
Solder Area
1.70
All dimensions are in millimeters
S3417
Figure 24. SKY81290 PCB Layout Footprint (3 x 3 TDFN)
15X Exposed
Solder Area
2.50
2.00
0.85
14X 0.75
Pin 1 Indicator
0.3 X 45°
0.40 Pitch
14X 0.20
All dimensions are in millimeters
S3418
Figure 25. SKY81290 PCB Layout Footprint (3 x 2 TDFN)
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DATA SHEET • SKY81290 1.2: A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Pin 1
Indicator
Skyworks P/N
Lot #
TDFN 3x3 Package
Skyworks P/N
Lot #
Pin 1
Indicator
TDFN 3x2 Package
Figure 26. Typical Case Markings
(Top View)
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DATA SHEET • SKY81290: 1.2 A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Pin 1
Indicator
3.00 ± 0.05
0.203 Ref.
Pin 1 Indicator
0.30 X 45°
1.65 ± 0.05
Exp. DAP
0.18 ± 0.05
0.400 BSC
2.5 ± 0.05
Exp. Pad
2.40 Ref
3.00 ± 0.05
0.00/0.05
0.425 ± 0.05
0.75 ± 0.05
Top View
Side View
Bottom View
All measurements are in millimeters.
S3266
Figure 27. SKY81290 14-Pin TDFN Package Dimensions (3 x 3 mm)
ø1.50 +0.10/–0
4.00 ± 0.10
3.30 ± 0.10 (Bo)
A
Pin 1
Indicator
1.75 ± 0.10
5.50 ± 0.05
B
A
12.00 ± 0.30
2.00 ± 0.05
0.30 ± 0.05
0.10 ± 0.10
1.10 ± 0.10 (Ko)
8.00 ± 0.10
B
0.10 ± 0.10
B
Notes:
1. Carrier tape material: black conductive polystyrene.
2. Cover tape material: transparent conductive material.
3. Cover tape size: 9.2 mm width
4. ESD surface resistivity is ≤ 1 x 1010 Ohms/square per EIA, JEDEC
tape and reel specification.
5. Ao and Bo measured on a plane 0.30 mm above the bottom of the pocket.
6. All measurements are in millimeters
R0.30
ø1.50 Min.
3.30 ± 0.10 (Ao)
A
S3416
Figure 28. SKY81290 Tape and Reel Dimensions (3 x 3 mm Package)
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DATA SHEET • SKY81290 1.2: A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
2.50 ± 0.05
Exp. Pad
0.18 ± 0.05
3.00 ± 0.05
0.33 ± 0.05
0.75 ± 0.05
0.80 ± 0.05
Exp. Pad
2.00 ± 0.05
0.00/0.05
0.203 Ref.
0.40 BSC
Pin 1
Indicator
Pin #1 Identification
Chamfer C0.30 X 45°
2.40 Ref.
Top View
Side View
Bottom View
S3268
All measurements are in millimeters.
Figure 29. SKY81290 14-Pin TDFN Package Dimensions (3 x 2 mm)
4.00
2.00 ± 0.05
ø1.5 + 0.1/–0
ø1.00 Min.
Pin 1 Indicator
1.75 ± 0.10
4.00 (Note 1)
3.50
R0.20 Max.
3.30 (Bo)
A
1.05 (Ko)
2.30 (Ao)
R0.25 Typ.
A
Notes:
1. Sprocket hole pitch cumulative tolerance ±0.2.
2. Carrier tape material: black conductive polystyrene.
3. Pocket position relative to sprocket hole measured as true position
of pocket, not pocket hole.
4. Cover tape material: transparent conductive material.
5. All measurements are in millimeters.
Figure 30. SKY81290 Tape and Reel Dimensions (3 x 2 mm Package)
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S3415
8.0 + 0.3/–0.1
A
0.30 ± 0.05
DATA SHEET • SKY81290: 1.2 A SINGLE FLASH LED DRIVER WITH AS2C INTERFACE
Ordering Information
Model Name
SKY81290 Single Flash LED Driver
Manufacturing Part Number
Evaluation Board Part Number
TDFN, 3 x 3 mm: SKY81290-11-564LF
SKY81290-11-564LF-EVB1
TDFN, 3 x 2 mm: SKY81290-11-563LF
SKY81290-11-563LF-EVB2
TDFN, 3 x 2 mm: SKY81290-11-563LFJ
SKY81290-11-563LFJ-EVB1
Copyright © 2012-2014 Skyworks Solutions, Inc. All Rights Reserved.
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information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to
update the materials or information and shall have no responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes.
No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or
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Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury,
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Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of
products outside of published parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for
applications assistance, customer product design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifications or parameters.
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