TLED2043

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4-CHANNEL WHITE LED DRIVER SLDS147C – JUNE 2002 – REVISED NOVEMBER 2002 1POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 /C0068 Integrated FETs with Low RDS-ON ... 6 Ω Max /C0068 Current-Controlled Output Drives That Are Proportional to Battery Voltage to Save Power /C0068 Integrated Power-Supply Switches for Power Savings During OFF State . . . 1 µA Max /C0068 Up to 89% Efficiency /C0068 Applications: LCD Display for Cell Phones, PDAs, Palmtops, etc. terminal assignments 1234 A D1 S1 S4 D4 B VIN1 VOUT2 SW VIN2 C IN+ VOUT1 VIN3 GND D FB NC IN– VOUT3 E D2 S2 D3 S3 NC – No internal connection TERMINAL DESCRIPTION D1, D2, D3, D4 Drain of FETs 1, 2, 3, and 4, respectively S1, S2, S3, S4 Source of FETs 1, 2, 3, and 4, respectively VIN1, VIN2, VIN3 Input of switches 1, 2, and 3, respectively VOUT1, VOUT2, VOUT3 Output of switches 1, 2, and 3, respectively SW Operates switches 1, 2, and 3 in unison Low input = switches are closed High input or Open = switches are open IN+ Noninverting input to current-control amplifier IN– Inverting input to current-control amplifier FB Provides feedback connection to IN– of current-control amplifier GND Device ground Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Copyright  2002, Texas Instruments IncorporatedPRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. SW VIN1 VOUT1 IN+ IN– FB V IN2 VOUT2 GND VIN3 VOUT3 NC PW PACKAGE (TOP VIEW) NC – No internal connection GQN PACKAGE (TOP VIEW) 1234 A B C D E

4-CHANNEL WHITE LED DRIVER SLDS147C – JUNE 2002 – REVISED NOVEMBER 2002

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description/ordering information The TLED2043 is a four-channel, white LED driver used for backlighting color LCD displays in portable equipment. The device consists of four FET outputs, each of which is used essentially as a current sink to bias a single LED. The gates of the FETs are controlled collectively by a current-control amplifier that automatically monitors the battery voltage. If the battery voltage drops when compared to an externally set reference voltage, the current-control amplifier proportionately lowers all four FETs’ output drives to conserve battery power. Additionally, the TLED2043 has internal switches that are programmed to disconnect the power supply and supporting circuitry to the device when LED operation is not needed, offering significant power savings during periods of inactivity. Offering smaller board space, lower R DS-ON , and lower overall cost, the TLED2043 has clear advantages over the use of discrete devices in implementing a white-LED driver solution. Compared to the use of charge pumps and dc-dc converters in similar applications, the TLED2043 again can offer the advantages of smaller board space and lower solution cost because no costly inductors and/or capacitors are required. In addition, it avoids the switching-noise and power-loss issues associated with such devices. Characterized for operation from –40°C to 85°C, the TLED2043 is offered in 20-pin TSSOP (PW) and MicroStar Jr. BGA (GQN) packages for maximum space savings.

ORDERING INFORMATION

TA PACKAGE † ORDERABLE PART NUMBER TOP-SIDE MARKING TSSOP (PW) Tube of 70 TLED2043IPW 2043I –40°C to 85°C TSSOP (PW) Reel of 2000 TLED2043IPWR 2043I VFBGA (GQN) Reel of 1000 TLED2043IGQNR 2043I † Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available at www.ti.com/sc/package. FUNCTION TABLE SW INPUT SWITCH 1, 2, 3 STATUS H All OFF L All ON Open All OFF

4-CHANNEL WHITE LED DRIVER SLDS147C – JUNE 2002 – REVISED NOVEMBER 2002 3POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 functional block diagram AMP1 VIN1 300 KΩ (TYP) VDD (Internal) VIN1 VOUT1 VIN2 VOUT2 VIN3 VOUT3 SW FB IN+ IN– Current-Control Amplifier absolute maximum ratings over operating free-air temperature range (unless otherwise noted)† † Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. NOTES: 1. All voltage values are with respect to the network ground terminal. 2. Maximum power dissipation is a function of TJ(max), θJA, and TA. The maximum allowable power dissipation at any allowable ambient temperature is PD = (TJ(max) – TA)/θJA. Operating at the absolute maximum TJ of 150°C can affect reliability. 3. The package thermal impedance is calculated in accordance with JESD 51-7.

4-CHANNEL WHITE LED DRIVER SLDS147C – JUNE 2002 – REVISED NOVEMBER 2002

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recommended operating conditions MIN MAX UNIT VIN1 2.7 5.5 VIN2 Switch input voltage 0 5.5 V VIN3 0 5.5 VSW Input voltage for SW pin 0 5.5 V IOUT1 3 IOUT2 Switch output current 3 mA IOUT3 3 VDS FET output drain-source voltage 5.5 V ID FET output drain current 50 mA TA Operating free-air temperature –40 85 °C electrical characteristics, TA = 25°C (unless otherwise noted) supply voltage switch section PARAMETER TEST CONDITIONS MIN TYP MAX UNIT VOUT1 VIN1 = 3.6 V, IOUT = 3 mA VIN–0.1 VOUT2 Switch output voltage VIN1 = 3.6 V, IOUT = 3 mA VIN–0.1 V VOUT3 VIN1 = 3.6 V, IOUT = 3 mA VIN–0.1 VSW High input voltage range for SW OFFVIN1 = 2.7 V to 5.5 V (see Note 4)VDD × 0.7 VVSW Low input voltage range for SW ONVIN1 = 2.7 V to 5.5 V (see Note 4) VDD × 0.3 V IL Low input current for SW VIN1 = 3.6 V, VSW = 0 V 20 100 µA IDD Input current (see Figure 1) ON state (VSW = 0 V) 1 mA IDD Input current (see Figure 1) OFF state (VSW = OPEN) 1 µA NOTE 4: V DD = VOUT1 amplifier (AMP1) section, VIN1 = 3.6 V PARAMETER TEST CONDITIONS MIN TYP MAX UNIT VIO Input offset voltage VIN1 = 2.7 V to 5.5 V, VIC × VIN or 100 mV TA = 25°C 0.3 4 mVVIO Input offset voltage VIC = 0.5 × VIN or 100 mV (see Figure 2) TA = Full range 5 mV IIO Input offset current 8 pA IIB Input bias current 45 pA VICR Common-mode input voltageVIN1 = 2.7 V to 5.5 V (see Figure 3) 0 VDD –1.5 V AVD Open-loop voltage gain 70 dB B1 Unity-gain bandwidth 630 kHz VOH Output voltage (FB) R L ≥ 100 kΩ (see Figure 4) VDD –1.5 V VOL Output voltage (FB) R L ≥ 100 kΩ (see Figure 5) 0.1 V constant-current circuit section, AMP + FET PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ID(OFF) Drain off-state current VIN1 = 3.6 V, SW: OFF (VSW = VDD or OPEN), VDS = 5.5 V 25 250 nA ron Drain-source ON resistanceVIN1 = 2.7 V, IN+ = 0.1 V, ID = 20 mA (see Figure 6) 6 Ω VS Source voltage VIN1 = 2.7 V to 5.5 V, FB = 200 mV, VD = 0.5 V, RL = 10 Ω (see Figure 7) 194 199 204 mV

0.5 VIN1

Figure 1. IDD (ON State)

0.5 VIN1 or 100 mV

Figure 2. VIO

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Figure 3. VICR Figure 4. VOH

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Figure 7. VS

Figure 8. Typical Application Circuit

4-CHANNEL WHITE LED DRIVER SLDS147C – JUNE 2002 – REVISED NOVEMBER 2002

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DEVICE OPERATION/APPLICATION HINTS Refer to the functional block diagram and typical application circuit (see Figure 8) White LEDs commonly are used to produce the backlight for small color LCDs found in portable electronics, such as cell phones and PDAs. Because the LED’s brightness and chromaticity are dependent on the LED’s bias current, precise control of this current is necessary for proper illumination of the LCD. The TLED2043 is, essentially, four voltage-controlled current sinks that are regulated in unison, with each current sink setting the bias current for one white LED. The basic circuitry and operation of the TLED2043 can be divided into three main operating blocks described below. output FETs The TLED2043 has four n-channel MOSFETs to drive four external LEDs. The FETs have a specified maximum r on of 6 Ω , while delivering 20 mA of load current. To determine the biasing current for each LED, the gate of each FET is driven by a buffer whose output is controlled by the current-control amplifier. current control amplifier The output of the Current Control Amplifier simultaneously drives four unity-gain amplifiers connected to the gates of the output FETs. To determine the drain current of each FET (the LED current), the noninverting input (IN+) of this amplifier typically is coupled to the battery voltage via Switch 1, while the inverting input (IN–) typically is coupled to a fixed reference voltage that remains constant as battery voltage changes. Therefore, the output of the Current Control Amplifier and the corresponding LED currents are proportional to the difference between the battery and reference voltages. As battery voltage drops with use, so does the LED current, allowing for lower power consumption to conserve battery power. switch 1, 2, 3 The TLED2042 has three switches that are opened/closed in unison via an active-low switch-enable (SW) pin; the switches are closed with a low input applied and opened with a high input. Each switch has a maximum loss of 0.1 V across it; thus, the output of each switch is specified to be (V IN – 0.1 V) < VOUT < VIN. During periods of inactivity when the LEDs are not needed, significant power savings can be achieved (from a maximum of 1 mA to 1 µA) by opening the switches. The purpose of each switch is described below:

• Switch 1: used to remove power to the TLED2043 when the LEDs are not needed.
• Switch 2 (or 3): used to remove power to the series voltage reference (VREF in the typical application Circuit). Without this switch, VREF current flows continuously (through R1 and R2), even when power is removed from the TLED2043. (Note that, if a shunt reference like the TLV431 is used, current still flows through the reference, even if Switch 2 is open).
• Switch 3: Though not used in the typical application circuit here, this switch can be used to connect various external circuitries to the current-control amplifier. One example is to connect an external voltage to either input of the current-control amplifier to implement an analog LED brightness control (see next section).

4-CHANNEL WHITE LED DRIVER SLDS147C – JUNE 2002 – REVISED NOVEMBER 2002 11POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TYPICAL CHARACTERISTICS efficiency Laboratory measurements and calculations have shown that the application circuit in Figure 8 typically has the following efficiency:

• Battery Voltage = 3.6 V: /C0104 = 78.8% (ILED = 12.2 mA)
• Battery Voltage = 3.3 V: /C0104 = 89% (ILED = 7.8 mA)
• Battery Voltage = 3.1 V: /C0104 = 80.4% (ILED = 4.5 mA) NOTE: Efficiency, as mentioned previously, refers to the efficiency of the overall solution and is defined simply as: /C0104 = PLED /PBATTERY where PBATTERY is the total power delivered by the battery to the entire circuit. Thus, the efficiency indicates how effectively the TLED2043 delivers power to the LEDs. As such, LED selection can have a significant impact on calculated efficiency. For instance, two different brands of LEDs may have different values of V F for the same value of IF. According to the equation above, the LED with the larger VF will dissipate more power (PLED = VF × IF) and thus will achieve higher efficiency. This result simply states how much power is dissipated in the LED, not how well that particular LED converts the electrical power into light–this, of course, solely depends on the LED construction and characteristics. It should be pointed out that although a lower calculated efficiency is achieved using the LED with the lower VF (for the same IF), the benefit of the lower VF is that there is now more headroom for LED operation as battery voltage drops. LED brightness control The brightness of an LED is proportional to its bias current. Since the current control amplifier determines the LED current by sensing the difference between its two inputs, changing the voltage at either IN– or IN+ (or both) affects LED current and brightness. There are several methods to achieve this. 1. Variable VREF : use an adjustable shunt regulator (e.g., TL431/TLV431) and a variable resistor to change voltage applied to IN– of the current-control amplifier.
• VREF ↑, brightness ↓ 2. External Analog Voltage, VBRIGHT : applied to either IN– or IN+ of the current-control amplifier.
• IN–: VBRIGHT ↑ , brightness ↓
• IN+: VBRIGHT ↑ , brightness ↑ NOTE: If using this method, VBRIGHT should be coupled resistively to the Current Control Amplifier via Switch 3, allowing it to be disconnected from the amplifier when the switches are opened. Doing so prevents wasted current flow from V BRIGHT to ground when no power is applied to the TLED2043. 3. Variable Resistors: use a variable resistor anywhere along the signal path of IN– or IN+ (R1–R8); this allows for adjustment of the voltage at IN– or IN+ (or both).

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When using equipment such as cell phones, often it is desirable to adjust the brightness of the LCD display. of achieving “digital” control of the LED brightness using standard resistors and signal switches. of the current-control amplifier, resulting in increased LED current and brightness. Figure 9. Example of a “Digital” Brightness Control

MPBG133C – APRIL 2000 – REVISED AUGUST 2002 1POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 GQN (R-PBGA-N20) PLASTIC BALL GRID ARRAY M0,05 0,65 0,08 4200704/D 07/2002 3,90 4,10 3,10 2,90 1,00 MAX 0,35 0,45 Seating Plane 1,95 TYP A 2,60 2 3 4 B C D E 0,15 0,25 0,325 0,65 A1 Corner Bottom View 20× NOTES: A. All linear dimensions are in millimeters. B. This drawing is subject to change without notice. C. MicroStar Junior/C0116 configuration D. Falls within JEDEC MO-225 variation BC. E. This package is tin-lead (SnPb). Refer to the 20 ZQN package (drawing 4204492) for lead-free. MicroStar Junior is a trademark of Texas Instruments.

MTSS001C – JANUARY 1995 – REVISED FEBRUARY 1999 1POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 PW (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE

14 PINS SHOWN

0,65 M0,10 0,10 0,25 0,50 0,75 0,15 NOM Gage Plane 9,80 9,60 7,90 7,70 2016 6,60 6,40 4040064/F 01/97 0,30 6,60 6,20 0,19 4,30 4,50 0,15 A 1,20 MAX 5,10 4,90 3,10 2,90 A MAX A MIN DIM PINS ** 0,05 4,90 5,10 Seating Plane 0°–8° NOTES: A. All linear dimensions are in millimeters. B. This drawing is subject to change without notice. C. Body dimensions do not include mold flash or protrusion not to exceed 0,15. D. Falls within JEDEC MO-153

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