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PRELIMINARY CM9311 Asymmetrical High Efficiency Two Channel Boost LED/OLED Driver
Features
* * * 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 internal power switch Disconnects LEDs during shutdown Low Profile TDFN-10 package Optional RoHS compliant lead free package
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. The proprietary FlexBoostTM 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. The CM9311 is available in a compact TDFN-10 package. It can operate over the industrial temperature range of -40C to 85C.
* * *
* * * * * * * * *
Applications
* * * * * Drives white LED backlighting and OLED Cellar phones Digital Cameras PDA, GPS, MP3 players Handheld devices
Typical Application
VIN 2.7V to 6.0V C IN 10 uF/10V
off on (by default)
L1 Enable 10 9 8 7 6 4.7 uH
D1 1A/20V
VOUT COUT 1 uF/16V
R SET 1 22K R SET 21 20K
1 2
ISET1 LED1
EN VOUT SW GND VIN
Channel CH1 CH2
3 4
VREF VSET2
PhotonICTM
CM9311
OLED
R SET 22
5 91K LED2
COLED
10 uF/16V
(c) 2006 California Micro Devices Corp. All rights reserved. 04/26/06
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PRELIMINARY CM9311
Package Pinout
PACKAGE / PINOUT DIAGRAM
TOP VIEW
(Pins Down View)
10 9 8 7 6
BOTTOM VIEW
(Pins Up View)
12345
Pin 1 Marking
CMxxx xxxxxx
GND PAD
12345
10 9 8 7 6
Note: This drawing is not to scale.
10-Lead TDFN Package (3mm x 3mm)
Ordering Information
PART NUMBERING INFORMATION
Lead Free Finish Pins 10 Package TDFN Ordering Part Number1 CM9311-01DE Part Marking
Note 1: Parts are shipped in Tape & Reel form unless otherwise specified.
Specifications
ABSOLUTE MAXIMUM RATINGS
PARAMETER ESD Protection (HBM) VIN to GND Pin Voltages VOUT, SW to GND LED1, LED2, to GND ISET1, VSET2, VREF, EN to GND Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering, 10s) RATING 2 [GND - 0.3] to +6.0 20 20 [GND - 0.3] to +5.0 -65 to +150 -40 to +85 300 UNITS kV V V V V C C C
(c) 2006 California Micro Devices Corp. All rights reserved.
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PRELIMINARY CM9311
Specifications (cont'd)
ELECTRICAL OPERATING CHARACTERISTICS (SEE NOTE 1)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VIN = 3.6V; CIN = 10F, COUT = 1F, COLED = 1F, L1 = 4.7H, interleave mode, TA = 25C (unless otherwise specified) VIN IQ VUVLO VOVP ISD VEN Input Voltage Range Quiescent Current Undervoltage Lockout ILED < 0.6mA (each channel), nonswitching VIN Rising 2.7 1.2 2.0 19.0 2.2 19.5 10 1.0 0.2 2 1 0.80 8 2 VIN = 3.0V to 6.0V, IOLED = 5mA to 20mA 1% divider resistors TA = 25C to 85C (Recommended) VIN = 3.0V to 6.0V Each Channel VIN = 2.7V to 6.0V Standard Load (Note 3) Standard Load (Note 3) VIN = 2.7V to 6.0V, ILED = 2mA to ILED MAX ISW = 0.8A, VGS = 15V Standard Load (Note 3) Standard Load (Note 3) ILED 1,2 = 20mA, 4WLED+OLED 1% RSET Accuracy, Each Channel Standard Load (Note 3) All Channels 0 5 300 85 0.5 770 3 0.2 0.6 100 VIN 50 95 500 20 1.180 10 5 3 1.220 20 1 1.260 50 20 x V VSET2 18 30 450 --------------R SET1 35 5 V V mA % % V A %/V mA V mVpp % m % A mW % mApp mA 6.0 2.0 2.4 20.0 15 V mA V V A V V mA
Output Overvoltage Protec- VOUT Rising tion Shutdown Current VEN = 0V Device Enable Threshold Device ON (by default) Device OFF VIN = 3.0V to 6.0V, RSET1(k 4 WLED
Channel 1 (WLED) LED Current (Note 1) ILED1
Number of WLEDs (Note 2) VIN = 2.7V to 6.0V VLED1 Voltage on LED1 Pin Standard load (Note 3) VIN = 2.7V to 6.0V Channel 2 (OLED) VOLED OLED Voltage (Note 4) IOLED OLED Current Range
VOLED / VOLED VOLED Regulation
VOLEDacc VREF IREF OLED Voltage Accuracy Reference Voltage VREF Divider Current
Boost Circuit (Note 3) ILED / ILED VIN Line Regulation IOUT VOUT VOUTR D RDSON Eff ISW PIN Control ILED acc ILEDR ILEDNL Boost Output Current Boost Output Voltage Output Voltage Ripple Duty Cycle Range MOSFET ON Resistance Efficiency Switch Peak Current Input Power Channel Current Matching (Note 5) LED Current Ripple No-Load Mode (Note 5)
(c) 2006 California Micro Devices Corp. All rights reserved. 04/26/06
490 N. McCarthy Blvd., Milpitas, CA 95035-5112
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Tel: 408.263.3214
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PRELIMINARY CM9311
Specifications (cont'd)
ELECTRICAL OPERATING CHARACTERISTICS (SEE NOTE 1)
SYMBOL fs PARAMETER Switching Frequency CONDITIONS VIN = 2.7V to 6.0V
( mA ) 450 = --------------------R
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 SET ( k )
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 k) 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: , V OLED = 20 x V SET2 , V VSET2 = ------------------------------------------ x 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
R SET22
(c) 2006 California Micro Devices Corp. All rights reserved.
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Tel: 408.263.3214
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PRELIMINARY CM9311
Typical Performance Curves
ILED vs. VIN
21 .2 21 .0 20.8 20.6
1 6
VOLED vs. VIN
ILED1
1 4
VOLED 12V
1 2
ILED (mA)
20.2 20.0 1 9.8 1 9.6 1 9.4 1 9.2 1 9.0 2 2.5 3 3.5 4 4.5 5 5.5 6
VOLED (V)
20.4
VOLED=10V
1 0
VOLED=8.5V
8
L = 4.7uH 4 WLED + OLED TA = 25 C
6
ILED1 = 20mA 4 WLED + OLED COLED = 10uF
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
4
VIN (V)
VIN (V)
EFFICIENCY v.s VIN
90
EFFICIENCY vs. ILED
90
Vin=5.6V
85
Efficiency (%)
Efficiency (%)
85
80
4.2V 3.6V 3.0V 2.7V
75
80
70
VOLED = 10V ILED1,2 = 20mA L = 4.7uH 4 WLED + OLED
75 2 3
65
ILED1,2 = 20mA VOLED = 10V L = 4.7uH 4 WLED + OLED TA = 25 C
0 5 1 0 1 5 20 25 30 35
60
VIN (V)
4
5
6
ILED (m A)
EFFICIENCY vs. INDUCTOR
90
EFFICIENCY vs. STRING CONFIGURATION
90 88 86
L=4.7uH L=3.3uH L=2.7uH L=1.5uH
CH1,2=20mA+20mA
85
Efficiency (%)
Efficiency (%)
80
84 82 80 78 76 74
CH1,2=5mA+20mA CH1,2=20mA+5mA
75
L=10uH L=15uH
70
VOLED = 10V ILED1 = 20 mA 4 WLED + OLED TA = 25 C
5 6
VOLED = 10V L = 4.7uH 4 WLED + OLED TA = 25 C
2 3 4 5 6
65 2 3 4
(c) 2006 California Micro Devices Corp. All rights reserved. 04/26/06
490 N. McCarthy Blvd., Milpitas, CA 95035-5112
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Tel: 408.263.3214
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PRELIMINARY CM9311
Functional Block Diagram
V IN
UVLO BIAS
OVP OSC PMW LOGIC D4
V OUT SW
Q4 R
VREF EN
ENABLE
BG
D1
L E D1
Q1
ISET1
CONTROL
VSET2
D2
L E D2
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 ( k ) = ------------------------ILED1 ( mA )
where ILED1 is the DC LED current in channel 1. 2 3 4 5 6 7 8 9 10 EPad LED1 VREF VSET2 LED2 VIN GND SW VOUT EN GND 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:
V OLED = 20 x V SET2
Pin to cathode of channel 2 LED string. Input supply voltage pin. Bypass with a 10F or larger ceramic capacitor to ground. 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 1.0F 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.
(c) 2006 California Micro Devices Corp. All rights reserved.
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490 N. McCarthy Blvd., Milpitas, CA 95035-5112
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Tel: 408.263.3214
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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. 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. 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 ( k ) = ---------------------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 x 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.
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(c) 2006 California Micro Devices Corp. All rights reserved. 04/26/06
490 N. McCarthy Blvd., Milpitas, CA 95035-5112
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Tel: 408.263.3214
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Fax: 408.263.7846
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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:
1V IN ( MIN ) x t ON 3V x 0.8 x --------------1MHz I PEAK -------------------------------------- ------------------------------------------- 0.5A L 4.7H
PWM signal
R SET1 ISET1(A) 22k VSET2 R SET1 ISET1(B) 91k CM9311
Diode Selection
(a) Schematic
25
20
ILED1(A) negative slope
ILED (mA)
1 5
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. 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 22F input capacitor and/or 2.2F output capacitor are recommended.
REF DES CIN COUT L1
1 0
ILED1(B) positive slope
5
0 0 1 0 20 30 40 50 60 70 80 90 1 00
DUTY (%)
(b) Brightness curves
Figure 1. Brightness Control Using Different Methods 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 minimal core losses. An inductance of 4.7H is optimum for most applications, but low DCR inductor values in 1.5-15H 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
(c) 2006 California Micro Devices Corp. All rights reserved.
DESCRIPTION Capacitor, 10F, 10V, Ceramic, 1206 Capacitor, 1F, 16V, Ceramic, 0805 Inductor, 4.7H, 1A, Low DCR
D1
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 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).
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490 N. McCarthy Blvd., Milpitas, CA 95035-5112
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PRELIMINARY CM9311
Application Information (cont'd)
In this case, because of small input ripple, the efficiency is about 2% higher. 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.
to VIN
CM9311
GND VIN 7 6 CF 0.1 uF/10V RF 100
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. 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.
Figure 3. Example CM9311 PC Layout and Compnent Placement for Standard Application
(c) 2006 California Micro Devices Corp. All rights reserved. 04/26/06
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Tel: 408.263.3214
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PRELIMINARY CM9311
Mechanical Details
TDFN-10 Mechanical Specifications Dimensions for the CM9311 packaged in a 10-lead TDFN package are presented below. For complete information on the TDFN-10, see the California Micro Devices TDFN Package Information document. Mechanical Package Diagrams
D
10 9 8 7 6
PACKAGE DIMENSIONS
Package JEDEC No. Leads Dim. A A1 A2 A3 b D D2 E E2 e K L # per tube # per tape and reel 1.30 0.20 1.40 2.20 0.18 Millimeters Min 0.70 0.00 0.45 Nom 0.75 0.02 0.55 0.20 0.25 3.00 2.30 3.00 1.50 0.50 1.50 0.30 1.70 0.40 0.051 0.008 NA 3000 pieces 1.60 0.055 2.40 0.087 0.30 0.007 Max 0.80 0.05 0.65 Min 0.028 0.000 0.018 TDFN MO-229 (Var. WEED-3)= 10 Inches Nom 0.030 0.001 0.022 0.008 0.010 0.118 0.091 0.118 0.060 0.020 0.060 0.012 0.067 0.016 Pin 1 ID
C0.35
E
Pin 1 Marking
Max 0.031 0.002 0.026
0.10 C
12345 TOP VIEW
0.012
0.08 C
0.094
A1
SIDE VIEW
A
A3 A2
0.063
1
2
3
4
5
GND PAD
Controlling dimension: millimeters
D2 L
=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.
K e
10
9
8
7
6
b
8X
E2
BOTTOM VIEW
0.10
M
CAB
Package Dimensions for 10-Lead TDFN
(c) 2006 California Micro Devices Corp. All rights reserved.
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Tel: 408.263.3214
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Fax: 408.263.7846
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www.cmd.com
04/26/06

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