SP7686/SP7686A
Constant Current Flash Driver in DFN 2mm x 3mm
January 2010
Rev. 2.1.0
GENERAL DESCRIPTION
The SP7686/SP7686A are current regulated
charge pumps ideal for powering high power,
high brightness LEDs for camera FLASH
applications of up to 500mA.
The charge pump automatically switches
between step-up and step-down modes
ensuring that the LED current does not depend
on the forward voltage. A low current sense
reference voltage (60mV to 360mV) allows the
use of small 0603 current sensing resistors.
The SP7686 has a DAC programmable
feedback reference voltage allowing the user
to precisely set FLASH and TORCH output
current levels, while the fixed version
SP7686A has set levels of FLASH and TORCH
reference voltage.
Both parts have over-
voltage, over-current, over-temperature and
FLASH time-out protection features.
The SP7686 and SP7686A are offered in a
RoHS compliant “green”/halogen free space
saving 8-pin 2x3mm DFN package.
APPLICATIONS
•
Cell Phone Flash
•
Cell Phone Torch
•
General LED applications
FEATURES
•
Output current up to 500mA
•
Up to 94% efficiency
•
Single Wire serial interface
•
2.4MHz switching frequency
•
FB Reference voltage adjusts in 10mV
steps from 60mV to 360mV
•
10nA Shutdown
•
PWM brightness control for DAC
•
Fast turn-on (<150μs)
•
3.5s Timeout function
•
Thermal shutdown protection
•
Built-in over-voltage and over-current
protection
•
Fixed output SP7686A
•
Automatic soft start limits in-rush
current
•
RoHS Compliant, “Green”/Halogen
Free 8-pin 2x3mm DFN
TYPICAL APPLICATION DIAGRAM
Fig. 1: SP7686 and SP7686A Application Diagrams
Exar Corporation
48720 Kato Road, Fremont CA 94538, USA
www.exar.com
Tel. +1 510 668-7000 – Fax. +1 510 668-7001
SP7686/SP7686A
Constant Current Flash Driver in DFN 2mm x 3mm
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation of
the device at these ratings or any other above those
indicated in the operation sections of the specifications
below is not implied. Exposure to absolute maximum
rating conditions for extended periods of time may affect
reliability.
V
IN
........................................................... -0.6V to 6.0V
C1, C2, EN, CTRL, FB, V
OUT
.....................-0.6 to V
IN
+0.3V
Storage Temperature .............................. -65°C to 150°C
Power Dissipation ............................... Internally Limited
1
Lead Temperature (Soldering, 10 sec) ................... 260°C
ESD Rating (HBM - Human Body Model) .................... 2kV
ESD Rating (HBM) EN ........................................... 1.2kV
OPERATING RATINGS
Input Voltage Range V
IN
............................... 2.7V to 5.5V
Ambient Temperature Range ..................... -40°C to 85°C
Thermal Resistance
θ
JA
...................................... 59°C/W
ELECTRICAL SPECIFICATIONS
Specifications with standard type are for an Operating Temperature of T
A
= 25°C only; limits applying over the full
Operating Temperature range are denoted by a “•”. Minimum and Maximum limits are guaranteed through test, design, or
statistical correlation. Typical values represent the most likely parametric norm at T
A
= 25°C, and are provided for reference
purposes only. Unless otherwise indicated, V
IN
= 3.6V, C
IN
=10μF, C
OUT
=2.2μF, C
FLY
=0.22μF, T
A
= –40°C to 85°C.
Parameter
Operating V
IN
Range
Operating Input Current
Shutdown Supply Current
Quiescent Current
FB Voltage for DAC=00000
FB Voltage for DAC=00001
FB Voltage for DAC=11111
FB DAC LSB
FB Voltage Accuracy
FB voltage (SP7686A, Torch)
FB Voltage (SP7686A, Flash)
FB Pin Current
Switching Frequency
Equivalent Resistance, 1x mode
Equivalent Resistance, 2x mode
Thermal Regulation
Thermal Shutdown Die Temperature
Thermal Shutdown Hysteresis
Settle time (TS) after last count
Ctrl Input Data Rate
Wake-up time (TPOR) from Vin off
Wake-up time (TON) from shutdown
Delay time (TDELAY) from 1st to
2nd pulse
Turn-off time (TOFF) into shutdown
Turn-off time (TOFFC )into shutdown
Time Duration before shutdown
Logic low voltage
2.8
200
3.5
25
0.5
140
15
15
1
600
200
75
50
350
4.2
0.4
50
2.0
2.4
0.6
8
0.01
-14
54
147
60
160
Min.
2.7
2
0.01
300
0
58
350
9.7
14
66
173
0.5
2.8
1.4
Typ.
Max.
5.5
3
1
Units
V
mA
μA
μA
mV
mV
mV
mV
%
mV
mV
μA
MHz
Ω
Ω
%/°C
°C
°C
μs
μs
μs
μs
μs
μs
μs
s
V
•
•
•
•
•
CTRL minimum pulse width
V
IN
pin low to high, 1 CTRL pulse, V
FB
=0mV
1 CTRL pulse or (EN pin low to high SP7686A)
1
st
to 2nd CTRL pulse time delay –
guaranteed by design
EN pin high to low (SP7686A)
CTRL pin high to low
V
FB
>120mV (SP7686, 11 CTRL pulses),
FLASH= high (SP7686A)
Driver shutdown
V
FB
= 60mV
Driver turns off
Driver turns on again
•
•
•
•
•
•
Variation from specified V
FB
Flash = LOW, Open loop comparator trip
voltage
Flash = HIGH, Open loop comparator trip
voltage
V
FB
=0.3V
•
Open loop comparator trip voltage
Open loop comparator trip voltage
•
Condition 1
V
IN
= 2.7 – 5.5V, FLASH = 0V, Iload = 100uA
V
CRTL
< 0.4V for > 350μsec,
V
EN
< 0.4V (SP7686A)
V
FB
= 0mV, DAC=00000
Conditions
© 2010 Exar Corporation
2/16
Rev. 2.1.0
SP7686/SP7686A
Constant Current Flash Driver in DFN 2mm x 3mm
Parameter
Logic high voltage
CTRL, EN pin current
Min.
1.4
0.5
Typ.
Max.
Units
V
μA
•
•
Driver enabled
(EN pin is SP7686A only)
Conditions
Note 1: Guaranteed maximum allowable power dissipation depends on the ambient temperature
BLOCK DIAGRAM: SP7686
Fig. 2: SP7686 Block Diagram
BLOCK DIAGRAM: SP7686A
Fig. 3: SP7686A Block Diagram
© 2010 Exar Corporation
3/16
Rev. 2.1.0
SP7686/SP7686A
Constant Current Flash Driver in DFN 2mm x 3mm
PIN ASSIGNMENT
SP7686 SP7686A
Fig. 4: SP7686 and SP7686A Pin Assignment
PIN DESCRIPTION: SP7686
Name
1
2, 3
Pin Number
V
IN
C1, C2
Description
Power supply input. Place a 10μF decoupling capacitor next to this pin.
Connect an external 0.22μF flying capacitor between these pins
This pin is used to control LED current. Once enabled the adjustable driver counts
positive going edges at this pin and sequentially increases FB voltage with 10mV steps
to a maximum 31 steps or 360mV. When this pin is held LOW for longer than 200μs
the SP7686 enters shutdown. The part can be enabled using this pin. The first positive
edge resets the part. A second positive edge sets the part to VFB=0. A third positive
going edge will increase FB voltage to 60mV and subsequent positive edges increment
VFB in 10mV steps. The voltage level can increase only and must be reset to zero by
the 200μs shutdown timer in order to go to a lower current value. The part will be
limited to a 3.5s on time when FB voltage is set to 120mV and above. This pin cannot
be left open.
Current feedback input. Place an external current sense resistor from this pin to ground.
Voltage at this pin will be internally compared to the DAC output (60mV – 360mV).
Ground pin for SP7686 bias and reference (low current).
Ground pin for power (high current).
Output voltage of the internal charge pump. Connect the LED between this pin and the
current sense resistor. Voltage at this pin will be regulated in order to maintain constant
LED current. Place a 2.2μF ceramic capacitor next to this pin.
4
CTRL
5
6
7
8
FB
SGND
PGND
V
OUT
© 2010 Exar Corporation
4/16
Rev. 2.1.0
SP7686/SP7686A
Constant Current Flash Driver in DFN 2mm x 3mm
PIN DESCRIPTION: SP7686A
Name
1
2, 3
Pin Number
V
IN
C1, C2
Description
Power supply input. Place a 10μF decoupling capacitor next to this pin.
Connect an external 0.22μF flying capacitor between these pins
The SP7686A uses the flash pin to switch between two internally preset voltage levels,
for Flash and Torch mode. The part is enabled and disabled by the separate ENABLE
pin. The part has a 3.5s maximum on time in Flash mode. After a 3.5s timeout occurs
the part shuts down and can be enabled by the FLASH or ENABLE pins. This pin cannot
be left open.
Current feedback input. Place an external current sense resistor from this pin to ground.
Voltage at this pin will be internally compared to 60mV or 160mV depending on the
logic level of the FLASH pin.
The SP7686A has this enable/shutdown pin. (Logic high = enable, logic low =
shutdown). Used to immediately disable the driver and PWM brightness control. There
is an internal pull down on this pin.
Ground pin for power (high current).
Output voltage of the internal charge pump. Connect the LED between this pin and the
current sense resistor. Voltage at this pin will be regulated in order to maintain constant
LED current. Place a 2.2μF ceramic capacitor next to this pin.
4
FLASH
5
FB
6
7
8
EN
PGND
V
OUT
ORDERING INFORMATION
Part Number
SP7686AER-L
SP7686AER-L/TR
SP7686ER-L
SP7686ER-L/TR
SP7686EB
Temperature
Range
-40°C≤T
A
≤+85°C
-40°C≤T
A
≤+85°C
-40°C≤T
A
≤+85°C
-40°C≤T
A
≤+85°C
SP7686EB
Marking
SP7686A
YYWWX
SP7686A
YYWWX
SP7686
YYWWX
SP7686
YYWWX
Package
2x3mm
DFN8
2x3mm
DFN8
2x3mm
DFN8
2x3mm
DFN8
Packing
Quantity
Bulk
3K/Tape & Reel
Bulk
3K/Tape & Reel
Note 1
Lead Free and
Halogen Free
Lead Free and
Halogen Free
Lead Free and
Halogen Free
Lead Free and
Halogen Free
Note 2
MSL L1@250°C
MSL L1@250°C
MSL L1@250°C
MSL L1@250°C
“YY” = Year – “WW” = Work Week – “X” = Lot Number
© 2010 Exar Corporation
5/16
Rev. 2.1.0
京公网安备 11010802033920号
EEWORLD
