PRELIMINARY CM9311 Asymmetrical High Efficiency Two Channel Boost LED/OLED Driver Features Product Description • • • The CM9311 is a high frequency, two-channel inductor-based PWM boost regulator specifically designed for constant current white LED and constant voltage OLED drive applications. With a maximum 19V/100mA output capability, the circuit can drive up to 5 WLEDs (5 series x 1 parallel) and one OLED, allowing up to 35mA per channel. With an input voltage range from 2.7V to 6.0V, it can operate from a single cell Li-Ion battery. • • • • • • • • • • • • Integrated WLED and OLED driver 2.7V to 6V input voltage range Up to 85% typical efficiency even for differenent channel loads in terms of LED number, LED current and LED dropout Excellent 5 series x 1 parallel WLED drive capability (35 mA per channel) OLED channel with up to 18V/30 mA capability Independent current/voltage setting using external low power resistors for each channel (no ballast resistors) No external frequency compensation needed Low (<1%) LED output ripple voltage and current Input undervoltage lockout and output over voltage protection 1 MHz fixed switching frequency (0.5 MHz option available) Uses small inductor and ceramic capacitors Integrated 0.3 Ω internal power switch Disconnects LEDs during shutdown Low Profile TDFN-10 package Optional RoHS compliant lead free package The proprietary FlexBoost™ architecture (patent pending) provides high efficiency (typical 85%) for a wide input voltage range, even for different channel loads in term of LED number, LED current and LED type. The maximum LED current and OLED voltage for each channel is independently programmed with external low-power resistors (no ballast resistors needed). A 1 MHz constant frequency PWM saves board space, allowing small, low-cost external components, and permitting designers to avoid sensitive IF bands in RF applications. The output over-voltage protection circuit prevents damage in the case of a high impedance output (e.g. faulty LED). The controlled current limit circuit prevents large inductor current spikes, even at startup. To avoid possible leakage currents, the EN control pin disconnects the LEDs from ground during shutdown. Applications • • • • • Drives white LED backlighting and OLED Cellar phones Digital Cameras PDA, GPS, MP3 players Handheld devices The CM9311 is available in a compact TDFN-10 package. It can operate over the industrial temperature range of -40°C to 85°C. Typical Application L1 D1 4.7 uH 1A/20V VIN 2.7V to 6.0V C IN on (by default) 10 uF/10V Enable VOUT COUT 1 uF/16V off R SET 1 22K 1 ISET1 2 LED1 R SET 21 20K R SET 22 EN 3 VREF VOUT PhotonICTM CM9311 4 VSET2 GND LED2 VIN 5 91K SW 10 Channel CH1 CH2 9 8 OLED 7 6 COLED 10 uF/16V © 2006 California Micro Devices Corp. All rights reserved. 04/26/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 1 PRELIMINARY CM9311 Package Pinout PACKAGE / PINOUT DIAGRAM TOP VIEW BOTTOM VIEW (Pins Down View) (Pins Up View) 10 9 8 7 6 1 2 3 4 5 CMxxx xxxxxx GND PAD Pin 1 Marking 10 9 8 7 6 1 2 3 4 5 10-Lead TDFN Package (3mm x 3mm) Note: This drawing is not to scale. Ordering Information PART NUMBERING INFORMATION Lead Free Finish Pins Package Ordering Part Number1 10 TDFN CM9311-01DE Part Marking Note 1: Parts are shipped in Tape & Reel form unless otherwise specified. Specifications ABSOLUTE MAXIMUM RATINGS PARAMETER RATING UNITS ±2 kV VIN to GND [GND - 0.3] to +6.0 V Pin Voltages VOUT, SW to GND LED1, LED2, to GND ISET1, VSET2, VREF, EN to GND 20 20 [GND - 0.3] to +5.0 V V V Storage Temperature Range -65 to +150 °C Operating Temperature Range -40 to +85 °C 300 °C ESD Protection (HBM) Lead Temperature (Soldering, 10s) © 2006 California Micro Devices Corp. All rights reserved. 2 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 04/26/06 PRELIMINARY CM9311 Specifications (cont’d) ELECTRICAL OPERATING CHARACTERISTICS (SEE NOTE 1) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VIN = 3.6V; CIN = 10μF, COUT = 1μF, COLED = 1μF, L1 = 4.7μH, interleave mode, TA = 25°C (unless otherwise specified) VIN Input Voltage Range IQ Quiescent Current 2.7 ILED < 0.6mA (each channel), nonswitching VIN Rising 6.0 V 1.2 2.0 mA 2.0 2.2 2.4 V 19.5 20.0 V 10 15 μA 0.2 V V 35 mA VUVLO Undervoltage Lockout VOVP 19.0 ISD Output Overvoltage Protec- VOUT Rising tion Shutdown Current VEN = 0V VEN Device Enable Threshold 1.0 Channel 1 (WLED) LED Current (Note 1) ILED1 Device ON (by default) Device OFF VIN = 3.0V to 6.0V, RSET1(kΩ 4 WLED 2 Number of WLEDs (Note 2) VIN = 2.7V to 6.0V VLED1 Voltage on LED1 Pin Channel 2 (OLED) VOLED OLED Voltage (Note 4) IOLED VOLEDacc 1 5 Standard load (Note 3) 0.80 VIN = 2.7V to 6.0V 8 OLED Current Range ΔVOLED / VOLED VOLED Regulation 450 --------------R SET1 20 × V VSET2 2 V 18 V 30 mA 5 VIN = 3.0V to 6.0V, IOLED = 5mA to 20mA % OLED Voltage Accuracy 1% divider resistors VREF Reference Voltage TA = 25°C to 85°C 1.180 1.220 1.260 V IREF VREF Divider Current (Recommended) 10 20 50 μA Boost Circuit (Note 3) ΔILED / ILED ⋅ ΔVIN Line Regulation 3 VIN = 3.0V to 6.0V Each Channel % 1 %/V IOUT Boost Output Current VIN = 2.7V to 6.0V 100 VOUT Boost Output Voltage Standard Load (Note 3) VIN VOUTR Output Voltage Ripple Standard Load (Note 3) Duty Cycle Range VIN = 2.7V to 6.0V, ILED = 2mA to ILED MAX MOSFET ON Resistance ISW = 0.8A, VGS = 15V 300 Eff ISW Efficiency Switch Peak Current Standard Load (Note 3) Standard Load (Note 3) 85 0.5 % A PIN Input Power ILED 1,2 = 20mA, 4WLED+OLED 770 mW 1% RSET Accuracy, Each Channel 3 % ILEDR Channel Current Matching (Note 5) LED Current Ripple 0.2 mApp ILEDNL No-Load Mode (Note 5) All Channels D RDSON Control ILED acc mA 20 50 5 Standard Load (Note 3) 0 V mVpp 95 % 500 mΩ 0.6 mA © 2006 California Micro Devices Corp. All rights reserved. 04/26/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 3 PRELIMINARY CM9311 Specifications (cont’d) ELECTRICAL OPERATING CHARACTERISTICS (SEE NOTE 1) SYMBOL fs PARAMETER Switching Frequency CONDITIONS VIN = 2.7V to 6.0V MIN 0.8 TYP 1.0 MAX 1.2 UNITS MHz Note 1: ILED is the average PWM current through the LED string with internal 2/3 duty cycle and a 6 ms period. The following formula must be used to calculate the LED current: I LED ( mA ) 450 = --------------------R SET ( kΩ ) Note 2: For lower LED forward voltage the number of LEDs can be increased up to the maximum output voltage limit. Note 3: Standard Load is a 4 series x 2 parallel WLEDS configured for ILED1 = 20 mA (RSET1 = 22 kΩ) and one OLED channel (CH2) which drives VOLED=12V and IOLED=20mA. Note 4: VVSET2, the voltage on VSET2 pin should be maintained in the 0.4V - 1.0V range. The following formulas are related to OLED channel settings: R SET22 , V OLED = 20 × V SET2 , V VSET2 = ------------------------------------------ × V REF R SET21 + R SET22 Note 5: [ILED(set) - ILED(effective)]/ILED(set) for each channel. Note 6: A ILED value below 0.6 mA for each channel set the circuit in no-load mode; all channels and MOSFET switch are in shutdown and DC circuit current consumption is limited to 1 mA (see quiescent current). V OLED = V OUT – V LED2 © 2006 California Micro Devices Corp. All rights reserved. 4 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 04/26/06 PRELIMINARY CM9311 Typical Performance Curves VOLED vs. VIN ILED vs. VIN 21.2 16 21.0 ILED1 20.8 14 VOLED 12V 12 20.4 VOLED (V) ILED (mA) 20.6 20.2 20.0 19.8 VOLED=10V 10 VOLED=8.5V 8 19.6 19.4 L = 4.7uH 4 WLED + OLED TA = 25 ºC 19.2 ILED1 = 20mA 4 WLED + OLED COLED = 10uF 6 19.0 4 2 2.5 3 3.5 4 4.5 5 5.5 6 2.0 2.5 3.0 3.5 VIN (V) 4.0 4.5 5.0 5.5 6.0 6.5 VIN (V) EFFICIENCY vs. ILED EFFICIENCY v.s VIN 90 90 Vin=5.6V 85 Efficiency (%) Efficiency (%) 85 80 VOLED = 10V ILED1,2 = 20mA L = 4.7uH 4 WLED + OLED 4.2V 3.6V 80 3.0V 2.7V 75 70 ILED1,2 = 20mA VOLED = 10V L = 4.7uH 4 WLED + OLED TA = 25 ºC 65 60 75 2 3 4 VIN (V) 5 0 6 25 30 35 CH1,2=20mA+20mA 88 86 Efficiency (%) Efficiency (%) 20 EFFICIENCY vs. STRING CONFIGURATION L=4.7uH 80 75 15 90 L=3.3uH L=2.7uH L=1.5uH 85 10 ILED (m A) EFFICIENCY vs. INDUCTOR 90 5 L=10uH L=15uH 70 VOLED = 10V ILED1 = 20 mA 4 WLED + OLED TA = 25 ºC 84 CH1,2=5mA+20mA 82 CH1,2=20mA+5mA 80 78 VOLED = 10V L = 4.7uH 4 WLED + OLED TA = 25 ºC 76 74 65 2 3 4 5 6 2 3 4 5 6 © 2006 California Micro Devices Corp. All rights reserved. 04/26/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 5 PRELIMINARY CM9311 Functional Block Diagram V IN UVLO BIAS BG VREF EN V OUT OVP OSC PMW LOGIC SW D4 Q4 ENABLE R D1 ISET1 L E D1 Q1 L E D2 CONTROL D2 VSET2 Q2 CM9311 GND Pin Descriptions PIN DESCRIPTIONS LEAD(s) NAME DESCRIPTION Channel 1 LED current set pin. Between this pin and GND connect the RSET1 1 ISET1 resistor, calculated as follows: R 450 SET1 ( kΩ ) = -------------------------ILED1 ( mA ) where ILED1 is the DC LED current in channel 1. 2 LED1 3 VREF Pin to cathode of channel 1 LED string. Reference voltage output pin, used to bias VSET2 node. The voltage on this pin sets the VOLED as follows: 4 VSET2 5 LED2 6 VIN Input supply voltage pin. Bypass with a 10μF or larger ceramic capacitor to ground. 7 GND Ground terminal pin. 8 SW 9 VOUT 10 EN EPad GND V OLED = 20 × V SET2 Pin to cathode of channel 2 LED string. Switching node. Internally connected to the drain of the integrated switch. Output voltage pin, which connects to the anodes of all LEDs. Bypass with a 1.0μF or greater ceramic capacitor to ground for low output ripple voltage. Enable pin. The circuit is ON when VEN is above 1.0V. The circuit is OFF when VEN is below 0.2V. Active High (ON) by default. Ground; backside exposed pad. © 2006 California Micro Devices Corp. All rights reserved. 6 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 04/26/06 PRELIMINARY CM9311 Application Information The CM9311 is a high efficiency, magnetic switchmode converter with current and voltage regulation driver ideally suited for driving white LEDs and OLED in Li-ion powered portable devices. The CM9311 is an asynchronous boost converter uses a low-resistance internal NMOS to drive small external inductor and Schottky diode. The CM9311 is the perfect converter for portable applications such as cellular phones, digital still cameras, PDAs and any application where small space, compact overall size and low system cost are critical. With a maximum 19V/100mA output capability, the circuit can drive up to 5 WLEDs (4 series x 1 parallel) and one OLED device, allowing up to 35 mA per channel. It includes a switch and an internally compensated loop for regulating the current into the LEDs. The CM9311 delivers a constant current to series-connected LEDs and a constant voltage to OLED, ensuring uniform brightness and color purity regardless of any LED forward voltage variations. The proprietary design architecture allows asymmetrical loading on each channel and maintains high efficiency (typ 85%) at low VIN resulting in longer battery life, and cool, reliable operation when an adapter is supplying high VIN. The maximum LED current or OLED voltage is independently programmed with external low power resistors avoiding ballast resistors. An 1MHz constant frequency PWM scheme saves board space with the use of small, low cost external components, allowing designers to avoid sensitive IF bands in RF applications. The circuit operates with low value inductors and low value output ceramic capacitors keeping voltage and current ripple in the 1% range. nal inductor and Schottky diode delivers the inductor’s stored energy to the load. Setting the LED Current The output current for channel 1 (up to 35 mA) is set by the value of its RSET resistor, located between the ISET1 pin and GND, according to the equations: 450 RSET ( kΩ ) = ---------------------ILED ( mA ) Setting the OLED Voltage The output voltage for the OLED is the difference between VOUT and the voltage at ILED2 pin. The voltage is programmed using the voltage divider R22 and R21, according to the equation: V OLED = 20 × V SET2 PWM Brightness Control The brightness WLEDs level can be continuously controlled for each channel using a PWM signal in 1-50 KHz range (recommended value is 10 kHz). As an example the PWM signal can be applied directly through RSET resistor for negative slope or by using a switch transistor for positive slope. See Figure 1 for different brightness control methods and results. Method A means negative slop and Method B means positive slope. The output over-voltage protection circuit prevents damage in the case of high impedance output (e.g. faulty LED). The controlled current limit circuit limit prevents large inductor current spikes, even at start-up. To avoid possible leakage currents the EN control pin disconnects the LEDs from ground during shutdown. CM9311 Operation When a voltage that exceeds the undervoltage lockout threshold (UVLO) is applied to the VIN pin, the CM9311 initiates a softstart which limits the inrush current while the output capacitors are charged. Following softstart, the CM9311’s internal NMOS drives an exter© 2006 California Micro Devices Corp. All rights reserved. 04/26/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 7 PRELIMINARY CM9311 Application Information (cont’d) selected based on the required load power and the minimum input voltage. The saturation current rating should be chosen well above the steady state peak inductor current. At minimum VIN and full duty cycle (worse case), this is approximately: R SET1 PWM signal ISET1(A) 22k VSET2 1 V IN ( MIN ) × t ON 3V × 0.8 × --------------1MHz I PEAK ≅ --------------------------------------- ≅ -------------------------------------------- ≅ 0.5A L 4.7μH R SET1 ISET1(B) 91k CM9311 Diode Selection (a) Schematic The low forward voltage and fast switching time make Schottky diodes the choice for high efficiency operation. Make sure the diode has a reverse voltage rating greater than the maximum output voltage. The diode conducts only when the power switch is on, so a peak current rating above 1A should be sufficient for a typical design. 25 ILED1(A) negative slope ILED (mA) 20 15 10 ILED1(B) positive slope Capacitor Selection 5 For proper performance, use surface-mount, low ESR ceramic capacitors for CIN and COUT. X7R or X5R ceramic dielectric provides good stability over the operating temperature and voltage range. 0 0 10 20 30 40 50 60 70 80 90 100 DUTY (%) (b) Brightness curves In most LED applications, high frequency output ripple is not a concern because it will not cause intensity variations that are visible to the human eye. Figure 1. Brightness Control Using Different Methods For such applications, when low ripple is needed, a 22μF input capacitor and/or 2.2μF output capacitor are recommended. Inductor Selection The inductor is used to store energy in a boost converter. The amount of energy stored in the inductor and transferred to the load is controlled by the PWM. The inductor is operated in the discontinuous conduction mode, and to assume proper operation, the inductor value must be limited to a maximum value. REF DES CIN COUT L1 An inductor with low series resistance (DCR) decreases power losses and increases efficiency. The core material should be capable of operating at I MHz with minimal core losses. An inductance of 4.7µH is optimum for most applications, but low DCR inductor values in 1.5–15μH range are also recommended for high efficiency applications. To ensure proper operation of the current regulator over a wide range of conditions, the inductor should be DESCRIPTION Capacitor, 10μF, 10V, Ceramic, 1206 Capacitor, 1μF, 16V, Ceramic, 0805 Inductor, 4.7μH, 1A, Low DCR Schottky Diode, 1A, 20V, SMD D1 SOURCE Murata, GRM319R61A106KE19D Vishay, VJ1206G106KXQ Murata, GRM188R61C105KA93D TDK, C2012X5R1C105K Coilcraft, LP06013-472ML TMP Electronics Co., SPC-03802-4R7 CHILISIN, SCD03015-4R7 SUMIDA, CDH3D13/S4R7 IR, MBRS120 CHENMKO, SSM5817S Input Filter If CM9311 is more than 4" from main power supply point, use an input RC filter to avoid high ripple and input transients to the circuit input pin (see Figure 2). © 2006 California Micro Devices Corp. All rights reserved. 8 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 04/26/06 PRELIMINARY CM9311 Application Information (cont’d) In this case, because of small input ripple, the efficiency is about 2% higher. to VIN CM9311 GND VIN 7 The ground connections for RSET(1,21,22) resistors should be kept separate from the high power grounds and connect directly to the ground pin to assure accurate current and voltage settings. For better heat flow, connect all NC pins to GND plane. Also connect the thermal landing to the bottom ground plane with thermal vias. RF 100 6 CF 0.1 uF/10V Figure 2. Input Filter Solution Layout Guide Components should be placed as close as practical to the IC to assure good performance. The input and output capacitors should be close, with minimum trace resistance and inductance. Reflected input ripple depends on the impedance of the VIN source, such as the PCB traces and the Li-ion battery, which has elevated impedance at higher frequencies. The input capacitor located near the converter input reduces this source impedance and ripple. Any ESR from the capacitor will result in steps and spikes in the ripple waveform, and possibly produce EMI. Figure 3. Example CM9311 PC Layout and Compnent Placement for Standard Application Route any noise sensitive traces away from the switching power components. Place the inductor and diode as close as possible to the SW pin to prevent noise emissions. © 2006 California Micro Devices Corp. All rights reserved. 04/26/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 9 PRELIMINARY CM9311 Mechanical Details TDFN-10 Mechanical Specifications Dimensions for the CM9311 packaged in a 10-lead TDFN package are presented below. Mechanical Package Diagrams For complete information on the TDFN-10, see the California Micro Devices TDFN Package Information document. D 10 9 8 7 6 PACKAGE DIMENSIONS TDFN JEDEC No. MO-229 (Var. WEED-3)= Leads 10 E Package Dim. Millimeters Pin 1 Marking Inches Min Nom Max Min Nom Max A 0.70 0.75 0.80 0.028 0.030 0.031 1 2 3 4 5 A1 0.00 0.02 0.05 0.000 0.001 0.002 TOP VIEW A2 0.45 0.55 0.65 0.018 0.022 0.026 b 0.20 0.18 D D2 0.30 0.007 3.00 2.20 E E2 0.25 0.008 2.30 e 1.50 0.012 0.118 2.40 0.087 3.00 1.40 0.010 0.10 C 0.091 0.08 C 0.094 A1 0.118 1.60 0.055 0.50 0.060 A SIDE VIEW A3 A2 0.063 0.020 K 1.30 1.50 1.70 0.051 0.060 0.067 L 0.20 0.30 0.40 0.008 0.012 0.016 # per tube NA # per tape and reel 3000 pieces 1 2 3 4 5 Pin 1 ID C0.35 E2 A3 GND PAD L D2 Controlling dimension: millimeters =This package is compliant with JEDEC standard MO-229, variation WEED-3 with exception of the "D2" and "E2" dimensions as called out in the table above. 10 K 9 8 7 6 b e 8X BOTTOM VIEW 0.10 M CAB Package Dimensions for 10-Lead TDFN © 2006 California Micro Devices Corp. All rights reserved. 10 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 04/26/06