PRELIMINARY CM9321 Asymmetrical High Efficiency Three Channel Boost LED/OLED Driver Features Product Description • • • The CM9321 is a high frequency, three-channel inductorbased PWM boost regulator specifically designed for constant current white LED and constant voltage OLED drive applications. With a maximum 19V/140mA output capability, the circuit can drive up to 10 WLEDs (5 series x 2 parallel) and one OLED, allowing up to 35 mA 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 asymmetrical channel loads in terms of LED number, LED current and LED dropout Excellent 5 series x 2 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 TQFN-16 package Optional RoHS compliant lead free packaing The proprietary FlexBoost™ architecture (patent pending) provides high efficiency (typical 85%) for a wide input voltage range, even for asymmetrical channel loads in term of LED number, LED current and LED type. A standard (noninterleave) version is also available using a MODE selection pin (not availalbe fo mass production). 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 which permits 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 start-up. To avoid possible leakage currents the EN control pin disconnects the LEDs from ground during shutdown. Applications • • • • • Drives white LED backlighting and OLED Cell phones Digital Cameras PDA, GPS, MP3 players Handheld devices The CM9321 is available in a compact TQFN-16 package. It can operate over the industrial temperature range of 40°C to 85°C. Typical Application VIN 2.7V to 6.0V CIN 10 uF/10V on (by default) 1 14 4.7 uH 1A/20V VOUT COUT 1 uF/16V 13 EN NC NC NC RSET 1 15 D1 Enable off 16 L1 CH1 VOUT 12 ISET1 Channel CH2 CH3 22K 2 CM9321 3 20K CREF 1 uF/6.3V RSET 3 5 6 11 10 9 OLED interlv (by default) no-interlv VIN 91K MODE LED3 VSET2 LED2 4 RSET 22 SW GND VREF ISET3 RSET 21 PhotonICTM LED1 8 7 22K 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 CM9321 Package Pinout PACKAGE / PINOUT DIAGRAM 7 LED3 8 VIN 11 SW 13 12 VOUT EN 1 10 GND 14 ISET1 TQFN16 4 X4 15 2 NC 3 LED1 NC VREF 9 MODE 16 4 NC VSET2 6 ISET3 5 LED2 Bottom View 16-Lead TQFN Package (4mm x 4mm) Note: This drawing is not to scale. Ordering Information PART NUMBERING INFORMATION Lead-free Finish Pins Package Ordering Part Number1 16 TQFN CM9321-01DE 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, LED3 to GND ISET1, VSET2, ISET3, 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 CM9321 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 OLED Current Range ΔVOLED / VOLED VOLED Regulation VOLEDacc 450 --------------R SET1 1 5 Standard load (Note 3) 0.80 VIN = 3.0V to 6.0V 8 VIN = 2.7V to 6.0V 2 20 × V VSET2 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 VIN = 3.0V to 6.0V, RSET1(kΩ) 4 WLED 2 450 --------------R SET1 30 mA Channel 3 (WLED) ILED3 LED Current (Note 1) 3 Number of WLEDs (Note 2) VIN = 2.7V to 6.0V VLED3 Voltage on LED3 Pin Boost Circuit (Note 3) ΔILED / ILED ⋅ ΔVIN Line Regulation 1 Standard load (Note 3) IOUT Boost Output Current VIN = 3.0V to 6.0V 140 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 D RDSON 5 0.80 V 1 %/V VIN = 3.0V to 6.0V Each Channel VOUT % mA 20 50 5 300 V mVpp 95 % 500 mΩ © 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 CM9321 Specifications (cont’d) ELECTRICAL OPERATING CHARACTERISTICS (SEE NOTE 1) SYMBOL Eff ISW PARAMETER Efficiency Switch Peak Current CONDITIONS Standard Load (Note 3) Standard Load (Note 3) Input Power ILED 1,2 = 20mA, 4WLED+OLED+2W 1% RSET Accuracy, Each Channel ILEDR Channel Current Matching (Note 5) LED Current Ripple ILEDNL No-Load Mode (Note 5) All Channels Switching Frequency VIN = 2.7V to 6.0V PIN Control ILED acc fs MIN TYP 85 0.65 Standard Load (Note 3) MAX 950 mW 3 % 0.2 mApp 0 0.8 UNITS % A 1.0 0.6 mA 1.2 MHz VIN = 3.6V; CIN = 10μF, COUT = 1μF, COLED = 1μF, L1 = 4.7μH, non-interleave mode (Note 7), TA = 25°C (unless otherwise specified) LED Current VIN = 3.0V to 6.0V, RSET(kΩ) 2 IMAX mA ILED 730-----------R SET PIN Input Power ILED 1,2,3 = 20mA, 4WLED+OLED+2W 990 mW 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 IsetLED = 20 mA each channel (RSET1 = RSET3 = 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 formulae are related to OLED channel settings: R SET22 V OLED = V OUT – V LED , 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). Note 7: For non-interleave mode, all parameters have the same min/typ/max interleave mode values, unless otherwise specified. © 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 CM9321 Typical Performance Curves VOLED vs. VIN ILED vs. VIN 16 21.2 21.0 ILED1 20.8 14 VOLED 12V 12 20.4 VOLED (V) ILED (mA) 20.6 20.2 20.0 19.8 VOLED=8.5V 8 ILED3 19.6 VOLED=10V 10 19.4 L = 4.7uH 4 WLED/ch TA = 25 ºC 19.2 ILED1,3 = 20mA CH1,2,3 = 4W+OLED+4W COLED = 10uF 6 4 19.0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 2.0 6.0 2.5 3.0 3.5 VIN (V) 4.0 4.5 5.0 5.5 6.0 6.5 VIN (V) EFFICIENCY v.s VIN EFFICIENCY vs. ILED 90 90 Vin=5.6V 85 Efficiency (%) Efficiency (%) 85 80 ILED1,2,3 = 20mA L = 4.7uH 4 WLED/ch 4.2V 3.6V 3.0V 2.7V 80 75 70 L = 4.7uH 4 WLED/ch TA = 25 ºC 65 60 75 2.0 2.5 3.0 3.5 4.0 4.5 5.0 VIN (V) 5.5 0 6.0 20 25 30 35 90 L=4.7uH CH1,2,3=20mA+10V+20mA 88 L=3.3uH L=2.7uH L=1.5uH 86 Efficiency (%) Efficiency (%) 15 EFFICIENCY vs. STRING CONFIGURATION 90 80 75 10 ILED (m A) EFFICIENCY vs. INDUCTOR 85 5 L=10uH L=15uH 70 84 CH1,2,3=5mA+10V+20mA 82 CH1,2,3=20mA+10V+5mA 80 78 VOLED = 10V ILED1,3 = 20 mA 4 WLED/ch TA = 25 ºC L = 4.7uH CH1,2,3 = 4W+OLED+2W TA = 25 ºC 76 74 65 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 2.0 2.5 VIN (V) 3.0 3.5 4.0 4.5 5.0 5.5 6.0 VIN (V) © 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 CM9321 Functional Block Diagram VIN EN ENABLE VOUT OVP UVLO BIAS VREF PMW LOGIC OSC SW D4 Q4 BG R ISET1 D1 LED1 Q1 VSET2 D2 CONTROL LED2 Q2 ISET3 D3 LED3 Q3 MODE CM9321 GND Pin Descriptions PIN DESCRIPTIONS LEAD(s) NAME DESCRIPTION Channel 1 LED current set pin. Between this pin and GND connect the RSET1 resistor, calculated as follows: 1 ISET1 450 R SET1 ( kΩ ) = ---------------------------I LED1 ( mA ) where ILED1 is the DC LED current in channel 1. 2 LED1 Pin to cathode of channel 1 LED string. 3 VREF Reference voltage output pin, used to bias VSET2 node. 4 VSET2 5 LED2 The voltage on this pin sets the VOLED as follows: V OLED = 20 × V SET2 Pin to cathode of channel 2 LED string. © 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 CM9321 Pin Descriptions (cont’d) PIN DESCRIPTIONS Channel 3 LED current set pin. Between this pin and GND connect the RSET3 resistor, calculated as follows: 6 ISET3 450 R SET3 ( kΩ ) = ---------------------------I LED3 ( mA ) where ILED3 is the DC LED current in channel 3. 7 LED3 Pin to cathode of channel 3 LED string. 8 VIN Input supply voltage pin. Bypass with a 10μF or larger ceramic capacitor to ground. 9 MODE When MODE is HIGH (default), the circuit uses interleave mode. When MODE is LOW (GND), the circuit uses non-interleave mode. 10 GND 11 SW 12 VOUT 13 EN 14 NC Not internally connected. For better heat flow, connect to GND. 15 NC Not internally connected. For better heat flow, connect to GND. 16 NC Not internally connected. For better heat flow, connect to GND. EPad GND Ground terminal pin. 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. Application Information The CM9321 is a high efficiency, constant frequency current regulating boost driver ideally suited for driving white LEDs to backlight LCD color displays and a camera flash in Li-ion powered portable devices. The CM9321 is the perfect driver 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 140mA/19V output capability, the circuit can drive up to 10 WLEDs (5 series x 2 parallel) allowing up to 35mA per channel. It includes a switch and an internally compensated loop for regulating the current into the LEDs. The CM9321 delivers a constant current to series-connected LEDs, 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 effi- ciency (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 for each channel is independently programmed with external low power resistors avoiding ballast resistors. A 1MHz constant frequency PWM scheme saves board space using of small, low cost external components , allowing designers to avoid sensitive IF bands in RF applications. The circuit operates with low value inductor and low value output ceramic capacitor keeping voltage and current ripple in the 1% range. 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 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. © 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 CM9321 Application Information (cont’d) CM9321 Operation When a voltage that exceeds the undervoltage lockout threshold (UVLO) is applied to the VIN pin, the CM9321 initiates a softstart which limits the inrush current while the output capacitors are charged. Following softstart, the CM9321's internal NMOS drives an external inductor and Schottky diode to deliver the inductor's stored energy to the load. switch transistor for positive slope. See Figure 1 for different brightness control methods and results. RSET1 PWM signal ISET1 22k VSET2 RSET3 ISET3 91k CM9321 Setting the LED Current The output currents for channel 1 (up to 40mA) and channel 3 (up to 30 mA) are set by the value of their RSET resistor, located between the ISET(1,3) pin and GND, according to the equations: (b) Non-interleave 25 ILED1 negative slope 20 450 R SET ( kΩ ) = ------------------------I LED ( mA ) ILED (mA) (a) Interleave (a) Schematic 730 R SET ( kΩ ) = -------------------------I LED ( mA ) 15 10 ILED3 positive slope 5 0 Setting the OLED Voltage 0 10 20 30 40 50 60 70 80 90 100 DUTY (%) The output voltage for the OLED is the difference between VOUT the voltage at ILED3 pin. The voltage is programmed using the voltage divider R22 and R21, according to the equation: (b) Brightness curves Figure 1. Brightness Control Using Different Methods V OLED = 20 × V SET2 Inductor Selection 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 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. 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 minimum core losses. An inductance of 4.7-µH is optimal for most applications, but low DCR inductor values in 1.5-15uH 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 selected based on the required load power and the minimum input voltage. The saturation current rating © 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 CM9321 Application Information (cont’d) should be chosen well above the steady state peak inductor current. At minimum Vin and full duty cycle (worse case), this is approximately: In this case, because of small input ripple, the efficiency is about 2% higher. to V IN Diode Selection LED3 CM9321 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. 7 Capacitor Selection 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. 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. For such applications, when low ripple is needed, a 22μF input capacitor and/or 2.2 μF output capacitor are recommended. REF DES CIN COUT L1 D1 DESCRIPTION Capacitor, 10μF, 10V, Ceramic, 1206 Capacitor, 1μF, 16V, Ceramic, 0805 Inductor, 4.7μH, 1A, Low DCR Schottky Diode, 1A, 20V, SMD 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 CM9321 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). GND 10 MODE 9 interlv (by default) VIN 1 V IN ( MIN ) × t ON 3V × 0.95 × --------------1MHz I PEAK ≅ --------------------------------------- ≅ ----------------------------------------------- ≅ 0.7A L 4.7μH non-interlv RF 100 CF 8 0.1 uF/10V Figure 2. Input Filter Solution Mode Selection Two working modes are available for CM9321: interleave mode (output voltage is periodically adjusted depending on each channel load) and non-interleave mode (same output voltage level for all channels). For interleave option, keep MODE pin floating (HIGH by default) and for non-interleave option, connect MODE pin to GND. 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. 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. The ground connections for RSET(1,21,22,3) 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 © 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 CM9321 Application Information (cont’d) thermal landing to the bottom ground plane with thermal vias. Figure 3. Example CM9321 PC Layout and Component Placement for Standard Application © 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 PRELIMINARY CM9321 Mechanical Details TQFN-16 Mechanical Specifications Mechanical Package Diagrams The CM9321 is supplied in a 16-lead, 4.0mm x 4.0mm QFN package. Dimensions are presented below. For complete information on the QFN16, see the California Micro Devices QFN Package Information document. D Package QFN-16 (4x4) Leads 16 Millimeters A A1 Nom Max 0.80 0.84 0.00 A3 0.04 Min 0.25 Max 0.031 0.033 0.15 C 0.002 0.15 C 0.00 0.20 REF b Nom .008 0.33 0.010 D 4.0 BSC 0.157 D1 1.95 REF 0.077 D2 2.05 E 2.15 E1 2.05 e 0.55 0.08 C 0.077 2.15 0.081 0.65 TYP. L 0.085 0.157 1.95 REF E2 0.10 C 0.081 4.0 BSC TOP VIEW 0.013 A3 A1 SIDE VIEW 0.085 A 0.026 0.65 0.022 # per tube xx pieces* # per tape and reel xxxx pieces D1 0.026 E2 Min Pin 1 Marking Inches E1 Dim. E PACKAGE DIMENSIONS Controlling dimension: millimeters D2 * This is an approximate number which may vary. L DAP SIZE 1.8 X 1.8 b e 16X 0.10 M CAB BOTTOM VIEW Package Dimensions for 16-Lead TQFN © 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 11