PRELIMINARY CM9320 Asymmetrical High Efficiency Two Channel Boost LED Driver Features Product Description • • The CM9320 is a high frequency, two-channel inductorbased PWM boost regulator specifically designed for constant current white LED drive applications. With a maximum 100 mA/19V output capability, the circuit can drive up to 10 WLEDs (5 series x 2 parallel) allowing up to 35 mA per channel. With a typical input voltage range from 2.7V to 6.0V, it can be operated from a single cell Li-Ion battery. • • • • • • • • • • • • 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 Up to 100 mA/19V output current/voltage Independent current setting using an external low power resistor for each channel (no ballast resistors) No external frequency compensation needed Low (<1%) LED output voltage and current ripple 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 low ON-Resistance (0.3 Ω) N-Chann el MOSFET switch Disconnects LEDs during shutdown Low profile TDFN-10 package Optional RoHS compliant lead free packaging The proprietary FlexBoost™ architecture (patent pending) provides high efficiency (typical 85%) for a wide input voltage range, even for asymmetrical channel loads in terms of LED number, LED current and LED type. The maximum LED current 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, permitting designers to avoid sensitive IF bands in RF applications. The output over-voltage protection circuit prevents damage in 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 LEDs for backlighting color LCD Cell phones MP3 players, PDA, GPS Digital Still Cameras LED flashlights Handheld devices The CM9320 is available in a compact TDFN-10 package. It can operate over the industrial temperature range of 40°C to 85°C. Typical Application VIN L1 2.7V to 6.0V CIN on (by default) 10 uF/10V Enable D1 4.7 uH VOUT 1A, 20V COUT 1 uF/16V off RSET1 1 22K 2 3 RSET2 EN ISET1 VOUT LED1 PhotonICTM NC CM9320 SW 4 ISET2 GND 5 LED2 VIN 10 Channel CH1 9 CH2 8 7 22K 6 © 2006 California Micro Devices Corp. All rights reserved. 05/08/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 1 PRELIMINARY CM9320 Package Pinout PACKAGE / PINOUT DIAGRAM Pin 1 Marking TOP VIEW BOTTOM VIEW (Pins Down View) (Pins Up View) 10 9 8 7 6 1 2 3 4 5 CMxxx xxxxxx GND PAD 10 9 8 7 6 1 2 3 4 5 CM9320-01DE 10 Lead TDFN Package Note: This drawing is not to scale. Ordering Information PART NUMBERING INFORMATION Lead Free Finish Pins Package Ordering Part Number1 10 TDFN CM9320-01DE 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, ISET2 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 05/08/06 PRELIMINARY CM9320 Specifications (cont’d) ELECTRICAL OPERATING CHARACTERISTICS (SEE NOTE 1) SYMBOL PARAMETER CONDITIONS MIN TYP VIN = 3.6V; CIN = 10μF, COUT = 1μF, L1 = 4.7μH, interleave mode, TA = 25°C (unless otherwise specified) VIN Input Voltage Range IQ Quiescent Current VUVLO Undervoltage Lockout VOVP Output Overvoltage Protection VOUT Rising ISD Shutdown Current VEN = 0V VEN Device Enable Threshold Device ON (by default) Device OFF V 1.2 2.0 mA V LED Current (Note 1) 2.2 2.4 19.0 19.5 20.0 V 10 15 μA 0.2 V V 35 mA 1.0 VIN = 3.0V to 6.0V, RSET1(kΩ) 4 WLED 2 1 Number of LEDs (Note 2) VIN = 2.7V to 6.0V Voltage on LED1 Pin Standard load (Note 3) Channel 2 ILED2 LED Current (Note 1) VIN = 3.0V to 6.0V, RSET2(kΩ) 4 WLED 2 Number of LEDs (Note 2) VIN = 2.7V to 6.0V 1 Voltage on LED2 Pin Standard load (Note 3) Boost Circuit (Note 3) ΔILED / ILED ⋅ ΔVIN Line Regulation IOUT 6.0 2.0 VLED1 VLED2 UNITS 2.7 ILED < 0.6mA (each channel), nonswitching VIN Rising Channel 1 ILED1 MAX 450 --------------R SET1 5 0.80 450 --------------R SET2 VIN = 3.0V to 6.0V 80 30 mA 5 VIN = 3.0V to 6.0V Each Channel Boost Output Current V 0.80 V 1 %/V mA Boost Output Voltage ILED 1,2 = 2mA to ILED MAX VIN 20 V Duty Cycle Range VIN = 2.7V to 6.0V, ILED 1,2 = 2mA to ILED MAX 5 95 % VOUTR Output Voltage Ripple Standard Load (Note 3) 50 RDSON VOUT D mVpp 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+1W 835 mW Channel Current Matching (Note 4) LED Current Ripple 1% RSET Accuracy, Each Channel 3 % 0.2 mApp No-Load Mode (Note 5) All Channels Switching Frequency VIN = 2.7V to 6.0V Control ILED acc ILEDR ILEDNL fs Standard Load (Note 3) 0 0.8 1.0 500 mΩ 0.6 mA 1.2 MHz © 2006 California Micro Devices Corp. All rights reserved. 05/08/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 3 PRELIMINARY CM9320 Specifications (cont’d) ELECTRICAL OPERATING CHARACTERISTICS (SEE NOTE 1) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VIN = 3.6V; CIN = 10μF, COUT = 1μF, L1 = 4.7μH, non-interleave mode (Note 6), TA = 25°C (unless otherwise specified) ILED ΔILED / ΔVIN PIN LED Current VIN = 3.0V to 6.0V, RSET(kΩ) Line Regulation @ High Load L = 4.7μH, VIN = 3.0V to 5.5V 4W+4W, 40mA+40mA L = 10μH, VIN = 3.0V to 5.5V 4W+4W, 50mA+40mA L = 10μH, VIN = 2.8V to 5.5V 3W+4W, 60mA+40mA ILED 1,2 = 20mA, 4WLED+1W Input Power 2 730-----------R SET IMAX mA 1 %/V 3 %/V 1 %/V 730 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 configuration set for IsetLED = 20 mA each channel (RSET1,2 = 22 kΩ). Generally, a "4W+1W" like formula denotes the WLED number of each channel, i.e. CH1+CH2 configurations. Note 4: [ILED(set) - ILED(effective)] / ILED(set) for each channel. Note 5: A LED current 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 6: 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 05/08/06 PRELIMINARY CM9320 Typical Performance Curves ILED vs. VIN ILED vs. VIN (high currents) 21.2 120 21.0 ILED1 20.8 110 L=10uH, 3W+4W, 60mA+40mA ILED1+ILED2 (mA) ILED (mA) 20.6 20.4 20.2 20.0 ILED2 19.8 19.6 19.4 100 L = 4.7uH 4 WLED/ch TA = 25 ºC 19.2 L=10uH, 4W+4W, 50mA+40mA 90 80 L=4.7uH, 4W+4W, 40mA+40mA 70 60 No-Interleave TA = 25 ºC 50 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 VIN (V) EFFICIENCY vs. ILED EFFICIENCY v.s VIN 90 90 Vin=5.6V 85 Efficiency (%) Efficiency (%) 85 80 ILED1,2 = 20mA L = 4.7uH 4 WLED/ch 4.2V 3.6V 80 3.0V 2.7V 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 5.5 0 6.0 5 10 15 VIN (V) 86 Efficiency (%) Efficiency (%) 35 ILED=20mA+20mA 88 L=3.3uH L=2.7uH L=1.5uH 80 75 30 90 L=4.7uH 85 25 EFFICIENCY vs. STRING CONFIGURATION EFFICIENCY vs. INDUCTOR 90 20 ILED (m A) L=10uH L=15uH 84 ILED=5mA+20mA 82 ILED=20mA+5mA 80 78 70 ILED1,2 = 20 mA 4 WLED/ch TA = 25 ºC L = 4.7uH CH1,2 = 4W+3W 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. 05/08/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 5 PRELIMINARY CM9320 Functional Block Diagram V IN UVLO BIAS BG EN V OU T OVP OSC PMW LOGIC D4 ENABLE SW Q4 R D1 ISET1 CONTROL L E D1 Q1 L E D2 D2 ISET2 Q2 CM9320 G ND Pin Descriptions PIN DESCRIPTIONS LEAD(s) NAME DESCRIPTION 1 ISET1 Channel 1 LED current set pin. Between this pin and GND connect the RSET1 resistor, calculated as follows: 450 R SET1 ( kΩ ) = ----------------------------I LED1 ( mA ) 2 LED1 Pin to cathode of channel 1 LED string. where ILED1 is the DC LED current in channel 1. 3 NC 4 ISET2 Not internally connected. For better heat flow, connect to GND. Channel 2 LED current set pin. Between this pin and GND connect the RSET2 resistor, calculated as follows: 450 R SET2 ( kΩ ) = ----------------------------I LED2 ( mA ) where ILED2 is the DC LED current in channel 2. 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 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. © 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 05/08/06 PRELIMINARY CM9320 Pin Descriptions (cont’d) PIN DESCRIPTIONS 10 EN EPad GND 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 CM9320 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 CM9320 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 100 mA/19V output capability, the circuit can drive up to 10 WLEDs (5 series x 2 parallel), allowing up to 35 mA per channel. It includes a switch and an internally compensated loop for regulating the current into the LEDs. The CM9320 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 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 for each channel is independently programmed with external low power resistors avoiding the need for 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. possible leakage currents, the EN control pin disconnects the LEDs from ground during shutdown. CM9320 Operation When a voltage that exceeds the undervoltage lockout threshold (UVLO) is applied to the VIN pin, the CM9320 initiates a softstart which limits the inrush current while the output capacitors are charged. Following softstart, the CM9320's internal NMOS drives an external inductor and Schottky diode that delivers the inductor's stored energy to the load. Setting the LED Current The output current is set by the value of the RSET connected between the ISET pin and GND, according to the equations: (a) Interleave 450 R SET ( kΩ ) = ------------------------I LED ( mA ) (b) Non-interleave 730 R SET ( kΩ ) = ------------------------I LED ( mA ) 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 output over-voltage protection circuit prevents damage in 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 © 2006 California Micro Devices Corp. All rights reserved. 05/08/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 7 PRELIMINARY CM9320 Application Information (cont’d) switch transistor for positive slope. See Figure 1 for different brightness control methods and results. RSET1 PWM signal ISET1 22k 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: 1 V IN ( MIN ) × t ON 3V × 0.8 × --------------1MHz I PEAK ≅ --------------------------------------- ≅ -------------------------------------------- ≅ 0.5A L 4.7μH RSET2 ISET2 91k CM9320 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 negative slope ILED (mA) 20 15 10 Capacitor Selection ILED2 positive slope 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. 5 0 0 10 20 30 40 50 60 70 80 90 100 DUTY (%) 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. (b) Brightness curves Figure 1. Brightness Control Using Different Methods For such applications, when low ripple is needed, a 22μF input capacitor and/or 2.2 μF 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. 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 4.7µH 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 REF DES CIN COUT L1 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 CM9320 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 05/08/06 PRELIMINARY CM9320 Application Information (cont’d) In this case, because of small input ripple, the efficiency is about 2% higher. to VIN CM9320 GND VIN 7 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 have 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 CM9320 PC Layout and Component 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. The ground connections for RSET(1,2) 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. © 2006 California Micro Devices Corp. All rights reserved. 05/08/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: 408.263.3214 l Fax: 408.263.7846 l www.cmd.com 9 PRELIMINARY CM9320 Mechanical Details TDFN-10 Mechanical Specifications Dimensions for the CM9320 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 05/08/06