PAM2810LED1G

4-Channel Programmable LED Current Sink PAM2810 Features n n n n n Description The PAM2810 provides 4 regulated current sinks, capable of sinking up to 40mA current to accommodate 4 white LEDs. It requires no charge pump, has no noise and EMI, and significantly improves the efficiency in Li bettery range. LED brightness can be controlled by PWM techniques. The constant current sink is set with an external sense resistor. Alternatively, a PWM signal applied to the EN pin can vary the anticipated brightness of the LED. The device is in shut down mode when the EN input is logic low. The PAM2810 is available in SOT23-8 and DFN 2 mmX2mm Packages. n n n n n Cost Effective LED Driver Support up to 4 White LEDs Output Current up to 40mA per LED Low Dropout Voltage Ultra Low Quiescent Supply Current: 65 μ A (typ) No Noise and EMI Shutdown Current Less than 1 μ A Over Temperature Protection Small Packages : SOT23-8 and DFN 2mmx2mm Pb-free Package Applications n White LED for LCD Display Backlights n White LED Keypad Backlights n 1-Cell Li-Ion Battery-operated Equipment Including PDAs, Hand-held PCs, Cellular Phone Typical Application Circuit VIN C1 0.1μF 4 VIN 2 EN LED1 8 1 LED2 7 PAM2810 LED3 6 LED4 5 GND 3 ISET R1 6.2 k Power Analog Microelectronics , Inc www.poweranalog.com 08/2008 Rev 1.1 1 4-Channel Programmable LED Current Sink PAM2810 Typical Application Circuit V BAT VIN C1 0.1μF 4 VIN 2 LED1 EN PAM2810 1 ISET LED4 GND R1 6.2kΩ 3 R1 6.2k Ω VIN C1 0.1μF 4 VIN 2 LED1 EN PAM2810 1 ISET LED4 GND 3 LED2 LED3 8 7 6 5 8 7 6 5 NC LED2 LED3 Block Diagram VIN VIN C IN 0.1 μ F 1.22V Ref LED1 LED2 LED3 LED4 EN ISET Current Setting Current Sinks RSET GND Power Analog Microelectronics , Inc www.poweranalog.com 08/2008 Rev 1.1 2 4-Channel Programmable LED Current Sink PAM2810 P in Configuration Top View DFN 2mmX2mm Top View SOT23-8 VIN GND EN ISET 1 2 3 4 8 7 6 5 LED1 LED2 LED3 LED4 ISET EN GND VIN 1 EJXYW 8 7 6 5 LED1 LED2 LED3 LED4 2 3 4 EJ: Product Code X: Internal Code Y: Year W: Week Pin Number DFN2x2 1 2 3 4 5 6 7 8 SOT23-8 4 3 2 1 5 6 7 8 Power Analog Microelectronics , Inc www.poweranalog.com 07/2008 Rev 1.1 EJX YW Name VIN GND EN ISET LED4 LED3 LED2 LED1 Description Input Voltage Ground Enable, Allow PWM Brightness Control, Active High LED Current Adjustment Pin LED4 Cathode Terminal LED3 Cathode Terminal LED2 Cathode Terminal LED1 Cathode Terminal 3 4-Channel Programmable LED Current Sink PAM2810 Absolute Maximum Ratings These are stress ratings only and functional operation is not implied . Exposure to absolute maximum ratings for prolonged time periods may affect device reliability . All voltages are with respect to ground . Input Voltage Range............................-0.3V to 6V Operation Junction Temperature.....-40°C to 125 °C PWM Pin voltage............... -0.3V to (VIN+0.3V)/6V Storage Temperature.....................-65 °C to 150 °C Maximum Junction Temperature..................150°C Soldering Temperature....................... 300°C,5sec Recommended Operating Conditions Input Voltage Range.......................... 2.7V to 5.5V Operation Temperature Range.........-40 °C to 85 °C Thermal Information Parameter Thermal Resistance (Junction to Ambient) Thermal Resistance (Junction to Case) Symbol Package SOT23-8 θJA DFN SOT23-8 θJC DFN 20 102 ºC/W 130 Maximum 250 Unit E lectrical Characteristic T A=25°C, V IN=3.6V, R SET=5.1k Ω, V LEDX=0.5V, unless otherwise noted. PARAMETER Input Voltage Output Current Current Matching Between Any Two Outputs Current Sink Dropout ISET PIN Voltage Output Current to Current Set Ratio Quiescent Supply Current Shutdown Supply Current EN Input Logic High EN Input Logic Low EN Pin Current Symbol V IN ILEDX ILED-MATCH VDROPOUT V SET ILEDX/ISET IQ ISHDN VHI V LO IEN V(EN) = 1.5V V(EN) = 0V 0.1 0.1 Rset=10MΩ,with no loads EN=logic low 1.4 0.4 1 1 Rset=3kΩ,ILEDX=40mA 1.22 100 65 0.1 80 1 μA μA V V μA μA VDD=5V CONDITIONS MIN Vf+V LED （Note） TYP 3.6 MAX 5.5 40 ±5 0.25 UNITS V mA % V V Note: Vf: LED forward voltage; V LED: voltage of LEDx pins. Power Analog Microelectronics , Inc www.poweranalog.com 07/2008 Rev 1.1 4 4-Channel Programmable LED Current Sink PAM2810 Typical Performance Characteristics T A=25°C, V IN=3.6V, R SET=5.1k Ω, V LEDX=0.5V, unless otherwise noted. LED Current VS LED Pin Voltage 45 40 LED Current (mA) 45 40 35 LED Curent VS Input Voltage 35 30 25 20 15 10 5 0 0 0.3 0.6 0.9 1.2 1.5 LED Pin Voltage(V) R=12.7KΩ R=4.3KΩ R=6.2KΩ R=3.2KΩ LED Curent(mA) 30 25 20 15 10 5 0 3 3.5 4 4.5 5 5.5 Input Voltage(V) R=12.7KΩ R=4.3KΩ R=6.2KΩ R=3.2KΩ VIset VS Input Voltage 1.2135 1.2125 LED Current VS Rset 50 45 40 LED Current(mA) 1.2115 Viset(V) 35 30 25 20 15 10 5 0 1.2105 1.2095 1.2085 1.2075 3 3.5 4 4.5 5 5.5 Input Voltage(V) 0 5 10 Rset(kΩ) 15 20 Efficiency VS Input Voltage 100 90 80 Efficiency(%) LED Current vs PWM Duty Cycle 30 25 LED Current (mA) 70 60 50 40 30 20 10 0 3 Rset=6.2k 20 15 10 5 0 3.25 3.5 3.75 4 4.25 4.5 0 20 40 60 80 100 Input Voltage(V) PWM Duty Cycle (%) Power Analog Microelectronics , Inc www.poweranalog.com 07/2008 Rev 1.1 5 4-Channel Programmable LED Current Sink PAM2810 A pplication Information The PAM2810 is a 4-channel programmable white-LED driver. The matched current regulators each have a 100:1 ratio between the LEDx outputs and the ISET current. The PAM2810 is capable of supplying 40mA per channel with the proper selection of the external RSET resistor, with a total of 160mA output current available. LED brightness control of PAM2810 can be achieved with a PWM signal. Output Current Capability The PAM2810 is capable of providing up to 40mA per LED under an input voltage of 2.7V to 5.5V. An external resistor is used to set the output current, as approximated with the following equation: R SET=100 *(1.22V / I LEDX ) In order that the output currents could be regulated properly, the LEDx pin voltage(V LEDX) must be larger than the dropout voltage of the current sink(V DROPOUT). To ensure the desired current is obtained, apply the following equation to determine the minimum input voltage: V IN - V DIODE = V LEDX ≥ V DROPOUT V DIODE is the diode forward voltage, and some typical value of V DROPOUT can be found from the following table. Table 1. I LED, R SET and V DROPOUT ILED 10mA 20mA 30mA 40mA RSET 12.7kΩ 6.2kΩ 4.3kΩ 3.2kΩ VDR OPOUT 40mV 80mV 120mV 150mV Table 2. PWM Frequency and Duty cycle Frequency 100Hz 1kHz 2 kHz 4 kHz 8 kHz 10 kHz Cycle 10ms 1ms 500μs 250μs 125μs 100μs Duty-Cycle Request > > > > > > 0.5 100 5 100 10 100 20 100 40 100 50 100 The maximum PWM frequency can be selected according to the table above. If the PWM frequency is much less than 100Hz, flickering may be seen in the LEDs. For the PAM2810, zero duty cycle will turn off the LEDs and a 50% duty cycle will result in an average ILED being half of the programmed LED current. For example, if RSET is set to program 20mA, a 50% duty cycle will result in an average ILED of 10mA. RSET should be chosen not to exceed the maximum current capability of the device. Shutdown When the EN pin is logic low, the PAM2810 will be in shutdown mode. While disabled, the PAM2810 typically draws 0.1 μ A current form the power supply. There is no internal pull-up or pull-down on the EN pin. Over Temperature Protection T h e PA M 2 8 1 0 e q u i p s o v e r t e m p e r a t u r e protection. When the junction temperature (T J) exceeds +150°C, the current source turns off automatically. The device will turn on again after the IC’s T J cools down under +125°C. Operating at absolute maximum temperature is not recommended. PWM Brightness Control Brightness control can be realized by applying a PWM signal to the EN pin. The constant current is set by the external resistor selected using the RSET equation. The LED brightness is proportional to the duty cycle (D) of the PWM signal. The PWM frequency (f) should be limited to accommodate the start-up time (50 μ s) of the device. D * (1/f) > 50 μ s Power Analog Microelectronics , Inc www.poweranalog.com 07/2008 Rev 1.1 6 4-Channel Programmable LED Current Sink Parallel LEDx Outputs for Increased Current Drive Output pins LED1 to LED4 may be connected together in any combination to sink higher current through fewer LEDs. For example in Figure 1, outputs LED1 and LED2 are connected together to drive one LED while LED3 and LED4 are connected together to drive a second LED. PAM2810 Connecting outputs in parallel does not affect internal operation of the PAM2810 and has no impact on the electrical characteristics. If less than four LEDs connected, the left pin can be floating or connected to GND, as shown in Typical Application Circuit on page 2.Connecting to GND is recommended. The current calculating method is the same as the RSET equation mentioned. Power Dissipation VIN Cin 0. 1μF LED1 LED2 LED3 LED4 The maximum allowable power dissipation that the package is capable of handling can be determined as follows: P DMAX = (T JMAX - T A) / θ JA Where T JMAX is the maximum junction temperature, T A is the ambient temperature, and θ JA is the junction-to-ambient thermal resistance of the specified package. The DFN 2x2 package has a θ JA of 80°C/W and the SOT23-8 250°C/W. This value of θ JA is highly dependant upon the layout of the PCB. The actual power dissipated by the PAM2810 follows the equation: P DISS=(V IN *I IN) - N(V DIODE * I LEDX) Where N equals the number of active outputs, V DIODE is the LED forward voltage, and I LEDX is the current supplied to the LEDx. Input Capacitor Selection EN GND ISET Rset Figure 1. Two Parallel Connected LEDs With this configuration, two parallel current sinks of equal value both provide current to each LED. If the current sink provides 10mA each, every LED can be drived with 20mA and gets double brightness. Other combinations of parallel outputs can be implemented similarly, such as in Figure 2. VIN Cin 0.1μF LED1 LED2 LED3 LED4 EN GND ISET Rset The PAM2810 is designed to work under a stable input voltage. To ensure the stability of input, it may be necessary to add a small input capacitor to help filter out any noise that probably appears on the line. Surface-mount multi-layer ceramic capacitors are recommended, which are small and inexpensive. A capacitance of 0.1 μ F is typically sufficient. Figure 2. One Parallel Connected LED Power Analog Microelectronics , Inc www.poweranalog.com 07/2008 Rev 1.1 7 4-Channel Programmable LED Current Sink PAM2810 Ordering Information PAM2810 X X Package Type Pin Configuration Pin Configuration A: 1: VIN 2: GND 3: EN 4: ISET 5: LED4 6: LED3 7: LED2 8: LED1 B: 1: ISET 2: EN 3: GND 4: VIN 5: LED4 6: LED3 7: LED2 8: LED1 Package Type A: SOT23-8 G: DFN 2x2-8 Part Number PAM2810AG PAM2810BA Marking EJXYW EJXYW Package DFN 2x2-8 SOT23-8 Shipping 3,000 units/Tape & Reel 3,000 units/Tape & Reel P lease consult PAM sales office or authorized distributors for more details . Power Analog Microelectronics , Inc www.poweranalog.com 07/2008 Rev 1.1 8 4-Channel Programmable LED Current Sink PAM2810 Outline Dimensions SOT23-8 (TYP) (MAX) 0.20 (REF.) (REF.) L1 ( REF.) Symbol A A1 A2 c D E E1 Dimensions In Millimet ers Min Max 1.45 MAX 0 0.10 1.10 1.30 0.12 (REF) 3.10 2.70 3.00 2.60 1.80 1.40 Symbol L L1 θ b e e1 Dimensions In Millimet ers Min Max 0.60 0.30 0.60 (REF) 10° 0° 0.38 0.22 0.65 (REF) 0.33 (REF) Power Analog Microelectronics , Inc www.poweranalog.com 07/2008 Rev 1.1 9 4-Channel Programmable LED Current Sink PAM2810 Outline Dimensions DFN 2x2 D B A 4 INDEX AREA (D/2 xE/2) 9 TOP VIEW E A C SEATING PLANE 8 0.08 C SIDE VIEW e Nxb Pin#1 ID 4 INDEX AREA (D/2 xE/2) E2 A1 D2 BOTTOM VIEW SYMBOL A A1 MIN 0.70 0.00 COMMON DIMENSION NOM MAX 0.75 0.80 0.02 0.05 Summary Table Lead Body Count Size 8 2X2 Lead Pitch (e) 0.50 Pin #1 ID R0.20 D BSC E BSC MIN b NOM MAX MIN D2 NOM MAX MIN E2 NOM MAX MIN L NOM MAX N 2.00 2.00 0.18 0.25 0.30 1.05 1.20 1.30 0.45 0.60 0.70 0.20 0.30 0.40 8 NxK Unit: Millimeters Power Analog Microelectronics , Inc www.poweranalog.com 08/2008 Rev 1.1 10 NxL