SP7616EB [EXAR]
High Accuracy 4-Channel Low Side LED Driver for CCFL Replacement; 高精度四通道低边LED驱动器，用于替代CCFL
| 型号： | SP7616EB |
| 厂家： | 
EXAR CORPORATION |
| 描述： | High Accuracy 4-Channel Low Side LED Driver for CCFL Replacement |
| 文件： | 总11页 (文件大小：1353K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SP7616
High Accuracy 4-Channel Low Side LED Driver for
CCFL Replacement
May 2009
Rev. 2.0.4
GENERAL DESCRIPTION
APPLICATIONS
The SP7616 is a 30V 4-Channel linear low side
LED driver. It is capable of powering up to four
LED strings of nine LEDs @ 60mA per string
for a total of 36 LEDs with 1.5% typical
current matching between channels. The
desired LED current can be adjusted with an
external resistor, and the precision string-to-
string current matching ensures consistent
color temperature across the whole display.
The device also features very low dropout
voltage to maximize system efficiency and
avoid difficult thermal design constraints.
Dimming can be achieved by feeding a PWM
signal to the PWM pin, or use an analog signal
to control the ISET current, this allows
brightness control without unwanted color
shifts. Fast LED current turn-on/off time allows
up to 5 kHz PWM dimming frequencies with as
low as 10% duty cycle, completely eliminating
flicker. The built-in thermal protection
prevents damage to the device under fault
conditions.
• CCFL replacement in TFT displays
• Panel backlighting
• Casino gaming light systems
• Advertising backlighting
FEATURES
• Wide 4.5V to 30V operating range
• 60mA LED current per channel
• 1.5% channel to channel current
matching
• Analog Dimming control
• PWM operation up to 5kHz with 10%
Duty Cycle
• Low dropout: 150mV @ 20mA
• Built-in Over Temperature Protection
• Small 2X3mm DFN package
− Lead Free, RoHS Compliant
TYPICAL APPLICATION DIAGRAM
Fig. 1: SP7616 Application Diagram
Exar Corporation
www.exar.com
48720 Kato Road, Fremont CA 94538, USA
Tel. +1 510 668-7000 – Fax. +1 510 668-7001
SP7616
High Accuracy 4-Channel Low Side LED Driver for
CCFL Replacement
ABSOLUTE MAXIMUM RATINGS
OPERATING 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.
Input Voltage Range VIN................................4.5V to 30V
Junction Temperature Range....................-40°C to 100°C
Thermal Resistance θJA ...................................... 59°C/W
ESD Rating (HBM - Human Body Model) ....................2kV
ESD Rating (MM - Machine Model)........................... 500V
Operating Junction Temperature............ -40°C to +125°C
Power Dissipation.................................Internally Limited
VIN............................................................-0.3V to 32V
LED1, LED2, LED3, LED4.............................-0.3V to 32V
ISET, PWM .................................................-0.3V to 6.0V
Storage Temperature.............................. -65°C to 150°C
Power Dissipation................................ Internally Limited
Lead Temperature (Soldering, 10 sec) ...................300°C
ELECTRICAL SPECIFICATIONS
Specifications with standard type are for an Operating Junction Temperature of TJ = 25°C only; limits applying over the full
Operating Junction 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 TJ = 25°C, and are provided for
reference purposes only. Unless otherwise indicated, VIN = 4.5V to 30V, CIN = 1uF, TJ = –40°C to 125°C.
Parameter
Min.
Typ.
Max.
Units
Conditions
Operating Input Voltage Range
Shutdown Supply Current
4.5
30
60
V
•
30
μA
Voltage at ISET is pulled to 3V Vin 30V
No LED connected, VLED pins are tied to
GND. RSET=1MΩ
Quiescent Supply Current
350
500
μA
Quiescent Supply Current
Quiescent Supply Current
LED Current Matching
1
1.5
3
mA
mA
%
ILED = 30mA
1.5
0.5
ILED = 60mA
-3
3
•
Relative to average of all 4 channels
VLED = 0.5V to 25V , VIN = 28V,
RSET =50kΩ
LED Current Line Regulation
0.1
0.05
60
1
%/V
% / V
mA
Line Regulation
0.1
VIN = 4.5V to 25V, VLED=0.5V (Note 2)
Maximum LED Current per
channel
RSET = 17.4kΩ,
LED Leakage Current
Dropout Voltage
2
μA
PWM pin LOW, VLED = 1V, VIN= 5V
(Note 3)
0.30
1075
1075
1
0.45
1118
1130
V
1032
1000
ILED = 30mA, RSET=35.833kΩ,
0°C ≤ TJ ≤ 125°C
Output Current Multiplication
Ratio K = ILED•RSET
•
ISET Voltage
V
Thermal Shutdown Die
Temperature
ILED = 0mA. LED current will self recover
when temperature drops below the trip
point, minus thermal shut down
hysteresis.
150
15
°C
Thermal Shutdown Hysteresis
20
°C
PWM Pin Logic LOW
PWM Pin Logic HIGH
PWM pin Hysteresis
0.8
5.5
V
V
Driver is disabled
Driver is active
2.4
400
mV
If ISET is pulled above this threshold the
device goes into full shutdown
ISET Shutdown Threshold
3
V
V
•
ISET Shutdown Threshold
Hysteresis
0.3
Typical PWM Maximum Dimming
Frequency
Applied to PWM pin. See typical
performance curves.
5
kHz
%
Typical PWM Dimming Duty
Cycle Range
Applied to PWM pin @ 5kHz. See typical
performance curves.
10
90
© 2009 Exar Corporation
2/11
Rev. 2.0.4
SP7616
High Accuracy 4-Channel Low Side LED Driver for
CCFL Replacement
Parameter
Min.
Typ.
Max.
Units
Conditions
Turn-on time from Shutdown
Turn-off time into Shutdown
100
300
20
μs
μs
VMOD from 5V to 0V, RSET = 50kΩ
VMOD from 0V to 5V, RSET = 50kΩ
Note 1: ILED Variations from specified by RSET value at VLED changing from 0.5 to 25V
Note 2: ILED Variations from specified by RSET value at VIN changing from 4.5 to 25V
Note 3: RSET = 31.6kΩ: Dropout voltage is measured as the VLED voltage where LED current drops 5% from nominal value
BLOCK DIAGRAM
Fig. 2: SP7616 Block Diagram
© 2009 Exar Corporation
3/11
Rev. 2.0.4
SP7616
High Accuracy 4-Channel Low Side LED Driver for
CCFL Replacement
PIN ASSIGNMENT
Fig. 3: SP7616 Pin Assignment
PIN DESCRIPTION
Name
Pin Number
Description
Input voltage for the IC. Connect a 1uF decoupling capacitor between this pin and
ground.
VIN
1
2
This pin must be held high to enable the output drivers. It can be used for PWM
dimming up to 5 kHz.
PWM
Connect resistor RSET from this pin to ground to set output current. Pulling this pin
above the shutdown threshold stated in the Electrical Specifications puts the IC into
shutdown mode.
ISET
GND
3
4
Ground return for LED currents and circuitry of the SP7616.
Connect an LED between each pin and VIN. Current value is controlled by RSET. The
current level through each pin is internally matched within 3%. Connect unused
channel(s) to GND to save current consumption.
LED1-4
5 - 8
ORDERING INFORMATION
Temperature
Part Number
Packing
Quantity
Marking
Package
Note 1
Note 2
Range
Lead Free and/or
Halogen Free
SP7616ER-L
-40°C≤TJ≤+125°C
-40°C≤TJ≤+125°C
8pin 2x3DFN
Bulk
Lead Free and/or
Halogen Free
SP7616ER-L/TR
SP7616EB
8pin 2x3DFN 3K/Tape & Reel
SP7616 Evaluation Board
“YY” = Year – “WW” = Work Week – “X” = Lot Number
© 2009 Exar Corporation
4/11
Rev. 2.0.4
SP7616
High Accuracy 4-Channel Low Side LED Driver for
CCFL Replacement
TYPICAL PERFORMANCE CHARACTERISTICS
All data taken at VIN = 8V, TJ = TA = 25°C, unless otherwise specified.
VIN
VIN
ILED 20mA/DIV
ILED 20mA/DIV
Typical Turn on Characteristics
Typical Turn Maximum Input Voltage
100
PWM Signal
PWM = 100Hz
80
PWM = 1KHz
PWM = 5KHz
60
VLED (Cathode Voltage)
ILED 20mA/DIV
40
20
0
0
20
40
60
80
100
PWM Duty Cycle (%)
PWM Duty Cycle Linearity
PWM Response 1kHz 10% Duty Cycle
PWM Signal
PWM Signal
VLED (Cathode Voltage)
VLED (Cathode Voltage)
ILED 20mA/DIV
ILED 20mA/DIV
PWM Response 1kHz 90% Duty Cycle
PWM Response 1kHz 50% Duty Cycle
© 2009 Exar Corporation
5/11
Rev. 2.0.4
SP7616
High Accuracy 4-Channel Low Side LED Driver for
CCFL Replacement
PWM Signal
VLED (Cathode Voltage)
ILED 20mA/DIV
PWM Response 5kHz 50% Duty Cycle
PWM Response 5kHz 90% Duty Cycle
35
30
25
20
15
10
5
0
5
10
15
20
25
30
Vin
PWM Response 5kHz 10% Duty Cycle
Typical Shutdown Current vs Input Voltage
70
60
50
40
30
20
10
0
0
0.2
0.4
0.6
0.8
1
V LED (Cathode Voltage)
Typical Dropout Performance
© 2009 Exar Corporation
6/11
Rev. 2.0.4
SP7616
High Accuracy 4-Channel Low Side LED Driver for
CCFL Replacement
THEORY OF OPERATION
INTRODUCTION
The SP7616 is a four-channel constant current
source LED driver with programmable output
current level. The design consists of a
regulator reference voltage source, current
amplifier, and output driver. The precision
reference voltage ensures good performance
over voltage and temperature. The four
outputs are tightly coupled allowing for
excellent LED current matching.
Figure 1
The RSET value may be determined from the
SETTING LED CURRENT
previous equation for VMOD = 0V.
The
equation below shows the effect of using a
VMOD in the circuit on the LED current.
The current in the LED strings is set by
adjusting the RSET resistor connected between
the ISET pin and ground. The LED current is
set using the following the following equation.
K
RSET
ILED ≈
(
1V − VMOD
)
mA
K
RSET
Where:
1V = Typical ISET Voltage
ILED =
mA
Where:
K = Output Current Multiplication Ratio
ILED is the desired LED current
K = Output Current Multiplication Ratio
ILED is the desired LED current
VMOD is the adjustment voltage
PWM DIMMING
Note that this method of current control is not
as precise as adjusting RSET. The voltage at
the ISET pin is adjusted slightly during
manufacturing to ensure that K, the output
current multiplication ratio, is as accurate as
The LED dimming control is done through the
PWM pin. The acceptable frequency range of
this signal is 100Hz to 5kHz. The acceptable
duty cycle range of the signal is 10% to 90%
at 1KHZ. When the PWM pin is driven low,
only the LED current sources are disabled
while the rest of the chip is still enabled.
possible.
When the SP7616 was originally
released at the end of 2006, the multiplication
ratio and ISET voltage were specified
separately.
However, market feedback for
better accuracy when using RSET alone
prompted the change to the way the part is
specified today.
ANALOG DIMMING CONTROL
Besides digital PWM control, the LED current
can be controlled continuously (from high to
low LED current) by raising the voltage at the
bottom of RSET, VMOD, from 0.0V to 1V
SHUTDOWN USING ISET PIN
In normal operation, the voltage at ISET pin is
around 1V. To ensure fast turn on at low duty
cycle and high PWM frequency, only the
output drivers are switching in PWM mode.
However, the whole chip can be shutdown by
pulling the voltage at ISET above 3V minimum.
maximum.
This configuration is shown in
figure 1 below.
© 2009 Exar Corporation
7/11
Rev. 2.0.4
SP7616
High Accuracy 4-Channel Low Side LED Driver for
CCFL Replacement
At 20mA LED current and VIN = 30V
additional power dissipated in the package is
equal to 600mW that will increase die
temperature to 59°C/W x 0.6W = 35.4C,
where 59°C/W is the package thermal
resistance. Assuming that all other channels
are working at VLED =1.5V the die temperature
will be approximately 41°C above ambient
temperature and that decreases operating
temperature range. Also to protect the part if
too many LEDs are shorted, and the VLED
voltage becomes to high, making the part
dissipates too much power, the over
temperature protection will shut the part off
VIN CONSIDERATIONS (IMPORTANT)
The VIN pin of the SP7616 (Pin 1) needs to be
connected to the anode of the LED for proper
operation. If these are not tied together, the
part can get into a latch condition as a result
of improper sequencing.
A second way the part can get into a latch
condition is if the input voltage falls below
1.5V but does not fall below 0.5V before the
power is re-applied.
In both cases, the latch condition can be
“reset” by pulling the input voltage below 0.5V
for >3 seconds. This latch is similar to what
one might experience with a uC if a reset was
not asserted after a brown out condition.
when
the
die
temperature
reaches
approximately 150°C.
OVER-TEMPERATURE PROTECTION
UNUSED CHANNELS AND LED 2 CHANNEL
(PIN 7)
The SP7616 has over-temperature protection
to prevent permanent damage to the device.
When the die temperature rises above 150°C
the output drivers are shut off. The output
current will self recover when the temperature
drops below the trip point with the preset
hysteresis of 15°C. Thus a part that shut off at
150°C will not try to restart unless the die
temperature is below 135°C
LED 2 channel should never be grounded or
left unconnected it should always be used
during operation. Other unused channels can
be tied to the ground to save on power
consumption.
SHORTED LEDS
If all LEDs on a string are shorted, the LED
cathode voltage will be VIN. It is still a
working condition for this device but it
significantly increases the dissipated power.
© 2009 Exar Corporation
8/11
Rev. 2.0.4
SP7616
High Accuracy 4-Channel Low Side LED Driver for
CCFL Replacement
Figure 2
Typical Application: CCFL Replacement powered from 3 Li-ion batteries.
Figure 3
Using the SP7616 from a fixed source
© 2009 Exar Corporation
9/11
Rev. 2.0.4
SP7616
High Accuracy 4-Channel Low Side LED Driver for
CCFL Replacement
PACKAGE SPECIFICATION
8PIN 2X3mm DFN
© 2009 Exar Corporation
10/11
Rev. 2.0.3
SP7616
High Accuracy 4-Channel Low Side LED Driver for
CCFL Replacement
REVISION HISTORY
Revision
Date
Description
Reformat. Increased shutdown current to 60uA. Changed specification methodology
for setting LED current. Multiplier value changed to 1075 typical. Changed room and
over temp limits. Dropout voltage changed to 300mV typical, 450mV maximum.
2.0.4
May 22, 2009 Added additional information in applications “VIN Considerations” section. Updated
resistor values for Maximum LED current per channel specification and current
multiplication ratio. Changed PWM frequency and PWM duty cycle to typicals and
referred to new curves in the typical performance graph section.
FOR FURTHER ASSISTANCE
Email:
customersupport@exar.com
Exar Technical Documentation:
http://www.exar.com/TechDoc/default.aspx?
EXAR CORPORATION
HEADQUARTERS AND SALES OFFICES
48720 Kato Road
Fremont, CA 94538 – USA
Tel.: +1 (510) 668-7000
Fax: +1 (510) 668-7030
www.exar.com
NOTICE
EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve
design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein,
conveys no license under any patent or other right, and makes no representation that the circuits are free of patent
infringement. Charts and schedules contained here in are only for illustration purposes and may vary depending upon a
user’s specific application. While the information in this publication has been carefully checked; no responsibility, however,
is assumed for inaccuracies.
EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or
malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its
safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in
writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes all
such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances.
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
© 2009 Exar Corporation
11/11
Rev. 2.0.4
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