Datasheet SP7615 Datasheet (Sipex)

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Page 1

Preliminary

Four Channel Constant Current LED Driver

FEATURES

■ Cost Effective LED driver

■ Constant current output ideal for Driving LED strings

■

Four Channel LED Driver provides matched LED curren

■ Current adjusted via an external resistor

■ PWM dimming possible

■ Small 2mm x 3mm DFN package

■ Outputs can be connected in parallel to

increase drive

■ Constant current for wide cathode voltage range (1.0V to 16V)

■ Highly integrated design, minimal components

■ Thermal shutdown protects the driver

Now Available in Lead Free Packaging

SP7615

GND

SET

8 Pin DFN

APPLICATIONS

■ Next Generation Mobile Phones

■ PDA, DSC, MP3 Players

■ Handheld Computers

■ LCD Display Modules

■ Keyboard Backlight

■ LED Displays

LED1

LED2

LED3

LED4

DESCRIPTION

The SP7615 is a linear constant current driver designed to drive multiple LEDs in series from a high input voltage rail. The driver acts as a high current matched, four-channel current source ensuring constant LED current for a range of input voltages. The SP7615 allows implementing the lowest cost LED driver for a variety of applications. Internal circuitry maintains the pre-set constant current output for a wide voltage range at the LED outputs (LED1,2,3,4). LED current can be adjusted up to The dimming can be achieved by controlling the I

125mA

per string with an external resistor.

input or by feeding a PWM signal to

SET

the EN pin. Fast EN turn-on and turn-off time allows for very fast PWM dimming frequencies, completely eliminating flicker. The built-in thermal protection automatically adjusts LED current to prevent overheating.

TYPICAL APPLICATION SCHEMATIC

C1 1n

GND

EN GND I

SET

SP7615

LED1

LED2 LED3 LED4

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ABSOLUTE MAXIMUM RATINGS

LED1, VLED2, VLED3, VLED4 Voltage to GND 0.3V to 16V

Vcc, V

ISET and EN Voltage to GND..................................... 6V

Output Current per LED (IOUT) ............................. 150mA

Power Dissipation per Package

8-pin DFN at TA = 85ºC ......................… 1.1W

Junction Temperature ..........................................+150ºC

Storage Temperature ........................... -55ºC to +150ºC

ESD Level. ....................................................... 2kV HBM

DFN Thermal Resistance......................................59ºC/W

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.

ELECTRICAL CHARACTERISTICS

4.5V < VCC <16V , VEN = 5V, VLED1 =VLED2 =VLED3 =VLED4 =1.0V, RSET =10kΩ or ISET=126µA, -40 < TA < 85ºC, Unless otherwise noted. Typical numbers are for TA = 25ºC.

PARAMETER MIN. TYP. MAX. UNITS CONDITIONS

Supply Voltage 4.5 5 16 V

= I

Quiescent Supply Current 20 39 mA I

Output/I

Current Multiplication Ratio

SET

700 1000 1200

LED1

LED Current (per diode) 126 mA LED to LED Current Matching -5 5 %

LED Current Line Voltage Regulation 0.15 0.6 %/V I

LED Current Load Voltage Regulation

24%/V 0.4V < V

change per volt VCC change

OUT

9%/V 1.0V < V

LED Current Thermal Regulation 0.1 %/ºC I

Pin Voltage 1.17 1.26 1.39 V I

SET

= 126mA

LED

= 1µA

SET

Thermal Shutdown Threshold 150 ºC

Thermal Shutdown Hysteresis 20 ºC

Current in OFF Mode 1 µAV

Min. ENABLE “ON Voltage” (Note1)

Max. ENABLE “OFF Voltage” (Note 2)

0.4 V

1.6 V

LED2

LED

= ZeroV

LED3

< 5V, I

=126mA

LED4

= 25mA

LED

= 126mA

LED

Note 1. ENABLE "ON" is VEN for which ILED > 80mA Note 2. ENABLE "OFF" is VEN for which ILED < 1uA@ VLED1 > 1.0V

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BLOCK DIAGRAM

GND

Bias

Figure 1. SP7615 Block Diagram

SET

Introduction

The SP7615 is a four channel constant current source LED driver with programmable output current level. The design consists of a regulator bandgap, voltage to current converter, and output mirror drivers. The bandgap ensures good performance over voltage and temperature. The four outputs are tightly coupled allowing for excellent channel matching.

Thermal Shutdown

The SP7615 uses a thermal comparator to monitor the system temperature shutting the device down if the internal temperature reaches

ºC. The device will remain off until the

150 internal temperature drops below 130

ºC.

Enable

The device has an enable function that is designed for TTL level inputs. This input will also track the V

pin so levels up to VCC are

Thermal Shutdown

Driver

V to I Converter

THEORY OF OPERATION

acceptable. The enable pin can also be used to control the LED brightness with a pulse width modulated control signal. Duty Cycle or PWM control of the LED current maintains constant LED color while brightness is changing. The SP7615 responds in less than 10µs to PWM signals applied to this pin.

SET

The I

pin is the servo point of an amplifier

SET

configured as a voltage to current converter. The voltage at this pin trips servos to the internal bandgap potential. A set resistor can be connected from the I

pin to ground to

SET

generate a reference current for the following current gain stages. A current could alternately be applied to this pin in the form of a current source or current output DAC. This pin can also have a PWM signal applied

to control the LED brightness.

LED1

LED2

LED3

LED4

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THEORY OF OPERATION

The R

1.26 * 1000/I I

SET

multiplication ratio, and I

value may be determined as R

SET

kΩ where 1.26 is a typical

OUT,

pin voltage, 1000 is a typical current

is a required

OUT

LED current in mA.

C1 1n

GND

EN GND I

SET

EN GND I

SET

C1 1n

GND

SP7615

LED1

LED2 LED3 LED4

LED1

LED2 LED3 LED4

EN GND I

SET

SP7615

LED1

LED2 LED3 LED4

D1 LED

CATHODE VOLTAGE, SUPPLY VOLTAGE

AND POWER DISSIPATION

The voltage applied to the cathode of each LED determines the overall efficiency of the SP7615 circuit. The SP7615 is designed to be able to sink 125mA at each of its four outputs; LED1 - 4. The SP7615 is also designed to be able to handle up to 16V on these pins. This voltage handling capability assumes the total power can be dissipated by the SP7615. The power dissipation inside the SP7615 will de directly related to the voltage and current applied to these pins. For example, the typical operating cathode

power dissipated by one LED driver output is 125mA * 500mV = 62.5mW. The following charts show the power dissipation of the SP7615 under various conditions. The power dissipation should be kept below

1.3W for safe operation and long term reliability at room temperature and derates to 530mW at 85ºC. While the above operating conditions are recommended, the part cannot be damaged due to internal temperature control as described above in the thermal shutdown section.

voltage is 500mV. At maximum current the

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PERFORMANCE GRAPHS

Figure 2 – Four Channel Total Power Dissipation versus Cathode Voltage at VCC = 5V

Figure 3 – Four Channel Total Power Dissipation versus Supply Voltage at Vcathode = 500mW

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TYPICAL PERFORMANCE CHARACTERISTICS

Figure 4 – LED Current versus I

Figure 5 – LED Current versus R

Current and Cathode Voltage, Vcc=5V, T= 27

SET

Value

SET

°°

°C

°°

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TYPICAL PERFORMANCE CHARACTERISTICS

Figure 6 – LED Current versus Temperature with Thermal Shutdown

Figure 7 – I

Voltage versus Temperature

SET

Page 8

TYPICAL PERFORMANCE CHARACTERISTICS

Figure 8 –PWM Signal Applied To The Enable Pin, Amplitude=5V, Duty Cycle=50%

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PACKAGE: 8 PIN DFN

Pin1 Designator to be within this

INDEX AREA

(D/2 x E/2)

D/2

E/2

TOP VIEW

D2/2

5678

E2/2

INDEX AREA

(D/2 x E/2)

4321

BOTTOM VIEW

(A3)

Seating Plane

SIDE VIEW

2x3 8 Pin DFN JEDEC MO-229 VARIATION VCED-2

SYMBOL

A A1 A3 K ¿

SIPEX Pkg Signoff Date/Rev: JL Aug18-05 / RevA

Dimensions in Millimeters:

Controlling Dimension

MIN NOM MAX MIN NOM MAX

0.80 0.90 1.00 0.032 0.036 0.039

0.00 0.02 0.05 0.000 0.001 0.002

0.20 REF 0.008 REF

0.20 - - 0.008 - -

b D D2 E E2 e L

0… - 14… 0… - 14…

0.18 0.25 0.30 0.008 0.010 0.012

1.50 - 1.75 0.059 - 0.069

3.00 BSC 0.118 BSC

1.60 - 1.90 0.063 - 0.075

0.30 0.40 0.50 0.012 0.016 0.020

Dimensions in Inches

Conversion Factor: 1 Inch = 25.40 mm

0.079 BSC2.00 BSC

0.020 BSC0.50 BSC

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ORDERING INFORMATION

Part Number Operating Temperature Range Package Type

SP7615ER .................................................. -40°C to +85°C ............................................ 8 Pin DFN (2 x 3mm)

SP7615ER/TR ............................................ -40°C to +85°C ............................................ 8 Pin DFN (2 x 3mm)

Available in lead free packaging. To order add "-L" suffix to part number.

Example: SP7615ER/TR = standard; SP7615ER-L/TR = lead free

/TR = Tape and Reel

Pack quantity is 3000 for DFN.

Corporation

ANALOG EXCELLENCE

Sipex Corporation

Headquarters and Sales Office

233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600

Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.

Datasheet SP7615 Datasheet (Sipex)

Specifications and Main Features

Frequently Asked Questions

User Manual