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
CM9311
PRELIMINARY
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 cur-
rent and LED dropout
Excellent 5 series x 1 parallel WLED drive capabil-
ity (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
Applications
Drives white LED backlighting and OLED
Cellar phones
Digital Cameras
PDA, GPS, MP3 players
Handheld devices
Product Description
The CM9311 is a high frequency, two-channel induc-
tor-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 FlexBoost
TM
architecture (patent pend-
ing) 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 per-
mitting designers to avoid sensitive IF bands in RF
applications. The output over-voltage protection circuit
prevents damage in the case of a high impedance out-
put (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 shut-
down.
The CM9311 is available in a compact TDFN-10 pack-
age. It can operate over the industrial temperature
range of -40C to 85C.
2.7V to 6.0V
22K
V
IN
1
91K
3
5
4
6
7
8
2
L1
D1
1 uF/16V
4.7 uH
1A/20V
10 uF/10V
V
OUT
C
OUT
10
9
20K
R
SET 1
R
SET 22
R
SET 21
Enable
on (by default)
OLED
CM9311
ISET1
GND
VSET2
VOUT
SW
LED2
VIN
LED1
EN
off
VREF
C
IN
Channel
CH1
CH2
10 uF/16V
C
OLED
PhotonIC
TM
Typical Application
Asymmetrical High Efficiency Two Channel Boost LED/OLED Driver
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
CM9311
PRELIMINARY
Ordering Information
Note 1: Parts are shipped in Tape & Reel form unless otherwise specified.
Specifications
PACKAGE / PINOUT DIAGRAM
Note: This drawing is not to scale.
10-Lead TDFN Package
(3mm x 3mm)
CMxxx
GND
4
3
2
1
4
3
2
1
6
7
8
9
PAD
xxxxxx
7
8
9
10
6
5
5
10
Pin 1
Marking
BOTTOM VIEW
(Pins Up View)
TOP VIEW
(Pins Down View)
PART NUMBERING INFORMATION
Pins
Package
Lead Free Finish
Ordering Part Number
1
Part Marking
10
TDFN
CM9311-01DE
ABSOLUTE MAXIMUM RATINGS
PARAMETER
RATING
UNITS
ESD Protection (HBM)
2
kV
VIN to GND
[GND - 0.3] to +6.0
V
Pin Voltages
V
OUT
, 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
Lead Temperature (Soldering, 10s)
300
C
Package Pinout
2006 California Micro Devices Corp. All rights reserved.
04/26/06
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Tel: 408.263.3214
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3
CM9311
PRELIMINARY
ELECTRICAL OPERATING CHARACTERISTICS
(SEE NOTE 1)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
= 3.6V; C
IN
= 10
F, C
OUT
= 1
F, C
OLED
= 1
F, L
1
= 4.7
H, interleave mode, T
A
= 25C (unless otherwise specified)
V
IN
Input Voltage Range
2.7
6.0
V
I
Q
Quiescent Current
I
LED
< 0.6mA (each channel), non-
switching
1.2
2.0
mA
V
UVLO
Undervoltage Lockout
V
IN
Rising
2.0
2.2
2.4
V
V
OVP
Output Overvoltage Protec-
tion
V
OUT
Rising
19.0
19.5
20.0
V
I
SD
Shutdown Current
V
EN
= 0V
10
15
A
V
EN
Device Enable Threshold
Device ON (by default)
Device OFF
1.0
0.2
V
V
Channel 1 (WLED)
I
LED1
LED Current (Note 1)
V
IN
= 3.0V to 6.0V, R
SET1
(k
4 WLED
2
35
mA
Number of WLEDs (Note 2) V
IN
= 2.7V to 6.0V
1
5
V
LED1
Voltage on LED1 Pin
Standard load (Note 3)
0.80
V
Channel 2 (OLED)
V
OLED
OLED Voltage (Note 4)
V
IN
= 2.7V to 6.0V
8
18
V
I
OLED
OLED Current Range
2
30
mA
V
OLED
/ V
OLED
V
OLED
Regulation
V
IN
= 3.0V to 6.0V,
I
OLED
= 5mA to 20mA
5
%
V
OLEDacc
O
LED
Voltage Accuracy
1% divider resistors
3
%
V
REF
Reference Voltage
T
A
= 25C to 85C
1.180
1.220
1.260
V
I
REF
V
REF
Divider Current
(Recommended)
10
20
50
A
Boost Circuit (Note 3)
I
LED
/ I
LED
V
IN
Line Regulation
V
IN
= 3.0V to 6.0V Each Channel
1
%/V
I
OUT
Boost Output Current
V
IN
= 2.7V to 6.0V
100
mA
V
OUT
Boost Output Voltage
Standard Load (Note 3)
V
IN
20
V
V
OUTR
Output Voltage Ripple
Standard Load (Note 3)
50
mVpp
D
Duty Cycle Range
V
IN
= 2.7V to 6.0V,
I
LED
= 2mA to I
LED MAX
5
95
%
R
DSON
MOSFET ON Resistance
I
SW
= 0.8A, V
GS
= 15V
300
500
m
Eff
Efficiency
Standard Load (Note 3)
85
%
I
SW
Switch Peak Current
Standard Load (Note 3)
0.5
A
P
IN
Input Power
I
LED 1,2
= 20mA, 4WLED+OLED
770
mW
Control
I
LED acc
Channel Current Matching
(Note 5)
1% R
SET
Accuracy, Each Channel
3
%
I
LEDR
LED Current Ripple
Standard Load (Note 3)
0.2
mApp
I
LEDNL
No-Load Mode (Note 5)
All Channels
0
0.6
mA
450
R
SET1
---------------
20 V
VSET2
Specifications (cont'd)
2006 California Micro Devices Corp. All rights reserved.
4
490 N. McCarthy Blvd., Milpitas, CA 95035-5112
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Tel: 408.263.3214
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CM9311
PRELIMINARY
Note 1: I
LED
is the average PWM current through the LED string with internal 2/3 duty cycle and a 6 ms period. The following for-
mula must be used to calculate the LED current:
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 I
LED1
= 20 mA (R
SET1
= 22 k
) and one OLED channel
(CH2) which drives V
OLED
=12V and I
OLED
=20mA.
Note 4: V
VSET2
, the voltage on VSET2 pin should be maintained in the 0.4V - 1.0V range. The following formulas are related to
OLED channel settings:
,
,
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 shut-
down and DC circuit current consumption is limited to 1 mA (see quiescent current).
fs
Switching Frequency
V
IN
= 2.7V to 6.0V
0.8
1.0
1.2
MHz
ELECTRICAL OPERATING CHARACTERISTICS
(SEE NOTE 1)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
ILED mA
(
)
450
RSET k
(
)
----------------------
=
V
OLED
V
OUT
V
LED2
=
V
OLED
20 V
SET2
=
V
VSET2
R
SET22
R
SET21
R
SET22
+
------------------------------------------ V
REF
=
Specifications (cont'd)
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
CM9311
PRELIMINARY
ILED vs. VIN
19.0
19.2
19.4
19.6
19.8
20.0
20.2
20.4
20.6
20.8
21.0
21.2
2
2.5
3
3.5
4
4.5
5
5.5
6
VIN (V)
IL
E
D
(
m
A
)
L = 4.7uH
4 WLED + OLED
TA = 25 C
ILED1
EFFICIENCY v.s VIN
75
80
85
90
2
3
4
5
6
VIN (V)
E
f
f
i
cien
cy
(
%
)
VOLED = 10V
ILED1,2 = 20mA
L = 4.7uH
4 WLED + OLED
EFFICIENCY vs. INDUCTOR
65
70
75
80
85
90
2
3
4
5
6
E
f
f
i
cien
cy
(
%
)
VOLED = 10V
ILED1 = 20 mA
4 WLED + OLED
TA = 25 C
L=4.7uH
L=3.3uH
L=2.7uH
L=1.5uH
L=10uH
L=15uH
EFFICIENCY vs. STRING CONFIGURATION
74
76
78
80
82
84
86
88
90
2
3
4
5
6
E
f
f
i
cien
cy
(
%
)
VOLED = 10V
L = 4.7uH
4 WLED + OLED
TA = 25 C
CH1,2=20mA+20mA
CH1,2=5mA+20mA
CH1,2=20mA+5mA
VOLED vs. VIN
4
6
8
10
12
14
16
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
VIN (V)
VO
L
E
D
(
V)
ILED1 = 20mA
4 WLED + OLED
COLED = 10uF
VOLED 12V
VOLED=8.5V
VOLED=10V
EFFICIENCY vs. ILED
60
65
70
75
80
85
90
0
5
10
15
20
25
30
35
ILED (mA)
E
f
f
i
cien
cy
(
%
)
ILED1,2 = 20mA
VOLED = 10V
L = 4.7uH
4 WLED + OLED
TA = 25C
Vin=5.6V
4.2V
3.6V
3.0V
2.7V
Typical Performance Curves
2006 California Micro Devices Corp. All rights reserved.
6
490 N. McCarthy Blvd., Milpitas, CA 95035-5112
l
Tel: 408.263.3214
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Fax: 408.263.7846
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www.cmd.com
04/26/06
CM9311
PRELIMINARY
Pin Descriptions
V IN
CM9311
ISET1
EN
SW
V OUT
LED2
LED1
VSET2
PMW
LOGIC
VREF
GND
CONTROL
OVP
Q1
Q2
Q4
D1
D2
D4
OSC
BG
UVLO
BIAS
R
ENABLE
PIN DESCRIPTIONS
LEAD(s)
NAME
DESCRIPTION
1
ISET1
Channel 1 LED current set pin. Between this pin and GND connect the R
SET1
resistor, calculated as follows:
where I
LED1
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
The voltage on this pin sets the VOLED as follows:
5
LED2
Pin to cathode of channel 2 LED string.
6
VIN
Input supply voltage pin. Bypass with a 10
F or larger ceramic capacitor to ground.
7
GND
Ground terminal pin.
8
SW
Switching node. Internally connected to the drain of the integrated switch.
9
VOUT
Output voltage pin, which connects to the anodes of all LEDs. Bypass with a 1.0
F
or greater ceramic capacitor to ground for low output ripple voltage.
10
EN
Enable pin. The circuit is ON when V
EN
is above 1.0V. The circuit is OFF when V
EN
is below 0.2V. Active High (ON) by default.
EPad
GND
Ground; backside exposed pad.
R
SET1 k
(
)
450
I
LED1 mA
(
)
--------------------------
=
V
OLED
20 V
SET2
=
Functional Block Diagram
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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7
CM9311
PRELIMINARY
The CM9311 is a high efficiency, magnetic switch-
mode 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, digi-
tal 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 cir-
cuit 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 for-
ward voltage variations.
The proprietary design architecture allows asymmetri-
cal loading on each channel and maintains high effi-
ciency (typ 85%) at low V
IN
resulting in longer battery
life, and cool, reliable operation when an adapter is
supplying high V
IN
. 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 capaci-
tors 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 pre-
vents large inductor current spikes, even at start-up. To
avoid possible leakage currents the EN control pin dis-
connects 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 cur-
rent while the output capacitors are charged. Following
softstart, the CM9311's internal NMOS drives an exter-
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 R
SET
resistor, located between the
ISET1 pin and GND, according to the equations:
Setting the OLED Voltage
The output voltage for the OLED is the difference
between V
OUT
and the voltage at I
LED2
pin. The volt-
age is programmed using the voltage divider R22 and
R21, according to the equation:
PWM Brightness Control
The brightness WLEDs level can be continuously con-
trolled 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 R
SET
resistor for negative slope or by using a
switch transistor for positive slope. See
Figure 1
for dif-
ferent brightness control methods and results. Method
A means negative slop and Method B means positive
slope.
R
SET k
(
)
450
I
LED mA
(
)
-----------------------
=
V
OLED
20 V
SET2
=
Application Information
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
CM9311
PRELIMINARY
Figure 1. Brightness Control Using
Different Methods
Inductor Selection
The inductor is used to store energy in a boost con-
verter. 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 1.515
H 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
should be chosen well above the steady state peak
inductor current. At minimum V
IN
and full duty cycle
(worse case), this is approximately:
Diode Selection
The low forward voltage and fast switching time make
Schottky diodes the choice for high efficiency opera-
tion. 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 typi-
cal design.
Capacitor Selection
For proper performance, use surface-mount, low ESR
ceramic capacitors for C
IN
and C
OUT
. X7R or X5R
ceramic dielectric provides good stability over the oper-
ating temperature and voltage range.
In most LED applications, high frequency output ripple
is not a concern because it will not cause intensity vari-
ations that are visible to the human eye.
For such applications, when low ripple is needed, a
22
F input capacitor and/or 2.2F output capacitor are
recommended.
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
).
CM9311
ISET1(A)
VSET2
PWM
signal
ISET1(B)
22k
R
SET1
91k
R
SET1
(a) Schematic
0
5
10
15
20
25
0
10
20
30
40
50
60
70
80
90
100
DUTY (%)
IL
E
D
(
m
A
)
ILED1(A)
negative slope
ILED1(B)
positive slope
(b) Brightness curves
REF
DES
DESCRIPTION
SOURCE
C
IN
Capacitor, 10
F,
10V, Ceramic, 1206
Murata, GRM319R61A106KE19D
Vishay, VJ1206G106KXQ
C
OUT
Capacitor, 1
F, 16V,
Ceramic, 0805
Murata, GRM188R61C105KA93D
TDK, C2012X5R1C105K
L
1
Inductor, 4.7
H, 1A,
Low DCR
Coilcraft, LP06013-472ML
TMP Electronics Co., SPC-03802-4R7
CHILISIN, SCD03015-4R7
SUMIDA, CDH3D13/S4R7
D
1
Schottky Diode, 1A,
20V, SMD
IR, MBRS120
CHENMKO, SSM5817S
I
PEAK
V
IN MIN
(
)
t
ON
L
---------------------------------------
3V 0.8
1
1MHz
----------------
4.7
H
-------------------------------------------- 0.5A
Application Information (cont'd)
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
CM9311
PRELIMINARY
In this case, because of small input ripple, the effi-
ciency is about 2% higher.
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 out-
put 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 ele-
vated 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 switch-
ing 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) resistors
should be kept separate from the high power grounds
and connect directly to the ground pin to assure accu-
rate 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 ther-
mal vias.
Figure 3. Example CM9311 PC Layout and
Compnent Placement for Standard Application
CM9311
GND
VIN
6
7
C
F
0.1 uF/10V
R
F
100
V
IN
to
Application Information (cont'd)
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
CM9311
PRELIMINARY
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 Cal-
ifornia Micro Devices TDFN Package Information docu-
ment.
=
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.
Package Dimensions for 10-Lead TDFN
PACKAGE DIMENSIONS
Package
TDFN
JEDEC
No.
MO-229 (Var. WEED-3)
=
Leads
10
Dim.
Millimeters
Inches
Min
Nom
Max
Min
Nom
Max
A
0.70
0.75
0.80
0.028
0.030
0.031
A1
0.00
0.02
0.05
0.000
0.001
0.002
A2
0.45
0.55
0.65
0.018
0.022
0.026
A3
0.20
0.008
b
0.18
0.25
0.30
0.007
0.010
0.012
D
3.00
0.118
D2
2.20
2.30
2.40
0.087
0.091
0.094
E
3.00
0.118
E2
1.40
1.50
1.60
0.055
0.060
0.063
e
0.50
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
Controlling dimension: millimeters
Mechanical Package Diagrams
BOTTOM VIEW
A
A3
A1
0.10 C
0.08 C
SIDE VIEW
TOP VIEW
b
L
0.10
C A B
M
8X
D2
E2
e
GND PAD
D
E
Pin 1
Marking
4
3
2
1
7
8
9
10
A2
K
7
8
9
10
3
2
1
4
5
6
5
6
Pin 1 ID
C0.35
Mechanical Details
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