CALMIRCO CM9132

PRELIMINARY
CM9132
Two Group, 3 and 2, WLED Driver, Different Current Settings
Features
Product Description
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•
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The CM9132 is an adaptive fractional switched capacitor (charge pump) regulator optimized for driving two
groups, 3 and 2, of white LEDs. Each group features
an individual ON/OFF control and individually set current. Each LEDs driver current is matched to within 2%
for uniform intensity. It supports an input voltage range
of 2.9V to 6V, with undervoltage lockout. A failure
detection circuit prevents the loss of power when one
or more LEDs fail (short or open). Internal over-temperature and over-current management provide short
circuit protection.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
2.9V to 6V input voltage range
Powers two display backlight and/or flash WLED
Low external parts count, requires no inductor and
ballast resistors
Low EMI and reflected ripple
Adaptive charge pump ratio (1x or 1.5x) maximizes
efficiency at both high and low input voltage
Precision regulation for each output with 2% current matching at 20-mA
Programmable LED current via ISET1 and ISET2
Independent Analog and PWM brightness control
Independent current setting for each group
Typical 500-KHz fixed switching frequency
Supports up to 300-mA, drives five LEDs regulated
to 50-mA each
Less than 10-µA shutdown current
Over-current and over-temperature protection
Short circuit protection with auto shutdown
Undervoltage lockout
Soft-start limits start-up inrush current
TQFN-16 package
Optional RoHS compliant lead free packaging
Applications
•
•
•
•
Drive white LEDs for STN/TFT Color LCD backlighting
Cell phones, PDAs with multiple displays
Digital Still Cameras
Flash for DSC
The CM9132 regulates up to 300-mA of output current
to drive WLEDs, allowing up to 50-mA per LED channel. The maximum LED current for each group is programmed with external resistors. Master plus two
independent enable inputs, allows for Analog and
PWM brightness control for each display. Either display can also be used for a camera flash. In full shutdown mode, the CM9132 draws only 10-µA.
The CM9132 automatically selects the most efficient
charge pump ratio based on the operating voltage
requirement of the white LEDs. The proprietary design
architecture maintains high efficiency (> 80%), and at
low VIN provides longer battery life. With a high VIN, or
when the adapter is powered, it provides cool reliable
operation.
The CM9132 is available in a compac,t 16-pin TQFN
package. It can operate over the industrial temperature
range of -40 °C to 85 °C.
Typical Application
1.0uF
2.9V to 6.0V
1.0uF
C1P C1N
C2P
VIN
VOUT
1uF
off
RSET1
on
Enable
RSET2
C2N
1uF
Display 1
LED1
EN
PhotonICTMLED2
CM9132
LED3
ISET1
ISET2
LED4
GND
LED5
Display 2
© 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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1
PRELIMINARY
CM9132
Package Pinout
PACKAGE / PINOUT DIAGRAM
7 LED5
8 C2N
11 C1N
14
13
12 NC
C2P
1
LED3
2
LED1
10 GND
15
C1P
9 EN
TQFN16
4X4
16
3
LED2
4
VIN
VOUT
ISET1
6 LED4
5 ISET2
Bottom View
16-Lead TQFN Package
(4mm x 4mm)
Note: This drawing is not to scale.
Ordering Information
PART NUMBERING INFORMATION
Lead-free Finish
Leads
Package
Ordering Part Number1
16
TQFN
CM9132-01QE
Part Marking
Note 1: Parts are shipped in Tape & Reel form unless otherwise specified.
Specifications
ABSOLUTE MAXIMUM RATINGS
PARAMETER
RATING
UNITS
±2
kV
[GND - 0.3] to +6.0
[GND - 0.3] to +7.0
[GND - 0.3] to +5.0
[GND - 0.3] to +5.0
V
V
V
V
Storage Temperature Range
-65 to +150
°C
Operating Temperature Range
-40 to +85
°C
300
°C
ESD Protection (HBM )
Pin Voltages
VIN to GND
VOUT to GND
ISET1, ISET2, EN to GND
All other pins to GND
Lead Temperature (Soldering, 10s)
© 2006 California Micro Devices Corp. All rights reserved.
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490 N. McCarthy Blvd., Milpitas, CA 95035-5112
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04/26/06
PRELIMINARY
CM9132
Specifications (cont’d)
ELECTRICAL OPERATING CHARACTERISTICS
VIN = 3.6V; All outputs are on. Typical values are at TA = 25°C.
SYMBOL
PARAMETER
CONDITIONS
MIN
VIN
Supply Voltage Range
VUVLO
Undervoltage Lockout
All outputs are no load.
IQ
Quiescent Current
1x mode
ISD
Shutdown Supply Current
VEN < 0.4V
2.9
VOUT Charge Pump
Output Voltage
VOUT
ILED TOT
TYP
1.7
1.8
6.0
UNIT
S
V
1.9
V
10
μA
5.5
V
300
mA
MAX
μA
500
2
4.2
IOUT = 0mA to 120mA,
VIN = 3.0 to 5.5V
Total ILED Current
Σ ILED1 thru ILED3+photoflash
Accuracy of ISET
VIN = 3.0V to 5.5V
1
Matching current between LED1
to LED3
ILED per driver
VIN = 4.0V, ILED 1,2,3 = 20mA
2
ILED
EN, ISET(1,2)
VIH
VIL
Device total ILED < 150mA
High Level Input Voltage
%
5
%
50
mA
1.8
Low Level Input Voltage
0.4
Protection
Over-current Limit
Over-temperature Limit
Over-temperature Hysteresis
400
135
15
mA
°C
°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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3
PRELIMINARY
CM9132
Typical Performance Curves
Charge Pump Efficiency
Source Current
Vled=3.2V
Input Current (mA)
Efficiency (%)
90
80
Iout=120mA
Iout=30mA
70
Iout=60mA
60
3.0
Vled=3.2V
200
100
3.5
4.0
4.5
5.0
5.5
175
150
Iout=120mA
125
100
75
Iout=60mA
50
Iout=30mA
25
3.0
6.0
3.5
Input Voltage (V)
4.0
4.5
5.0
5.5
Input Voltage (V)
Typical Waveforms
Typical Waveforms
Cin=C2=C3=Cout=1uF, Iout=120mA
Cin=C2=C3=Cout=1uF, Iout=120mA
100 mV/
div
Vout
20mA/
div
Iin
50mV/
div
Vin
1.0x mode
6.0
100 mV/
div
Vout
20mA/
div
Iin
50mV/
div
Vin
1us/div
1.5x mode
1us/div
LED Current vs. Vin
Startup
Cin=C2=C3=Cout=1uF, Iout=120mA
1V/
div
EN
200mA/
div
Iin
2V/
div
Vout
LED Current (mA)
25
20
15
10
5
3.0
.5ms/div
3.5
4.0
4.5
5.0
5.5
6.0
Input Voltage (V)
© 2006 California Micro Devices Corp. All rights reserved.
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490 N. McCarthy Blvd., Milpitas, CA 95035-5112
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04/26/06
PRELIMINARY
CM9132
Functional Block Diagram
C1P C1N
C2P C2N
Charge Pump x1, x1.5
VIN
OSC
500 KHz
UVLO
VOUT
Bandgap
LED1
LED2
Mode Select
Current
Sinks
LED3
Failed LED
Condition
EN
LED4
LED5
CM9132
GND
ISET1
ISET2
Pin Descriptions
PIN DESCRIPTIONS
LEAD(s)
NAME
DESCRIPTION
1
LED1
Cathode of LED1 pin.
2
C1P
This pin is the plus side of charge pump bucket capacitor C1. Connect a 1.0-µF
ceramic capacitor with a voltage rating of 10 V or greater between C1N and C1P.
3
VIN
Positive supply voltage input pin. This voltage should be between 2.9V and 6V.
This pin requires a 1.0-µF or larger ceramic capacitor to ground.
Current set and shutdown pin for group one drivers, active low. Pull high to
shutdown the group.
To set the LED current, a resistor, RSET, is connected between this pin and ground.
The regulated LED current is 1000x the current flowing in RSET, and is
4
ISET1
approximately;
0.66V – ( LogicLow )
I LED = ----------------------------------------------------- × 1000
R SET
If this resistor is tied to directly ground (and enable function not used) Logic Low =
0, otherwise subtract the voltage drop of the device that drives this pin low.
© 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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5
PRELIMINARY
CM9132
Pin Descriptions (cont’d)
PIN DESCRIPTIONS
Current set and shutdown pin for group two drivers, active low. Pull high to
shutdown the group.
To set the LED current, a resistor, RSET, is connected between this pin and ground.
The regulated LED current is 1000x the current flowing in RSET, and is
5
ISET2
approximately;
0.66V – ( LogicLow )
I LED = ----------------------------------------------------- × 1000
R SET
If this resistor is tied to directly ground (and enable function not used) Logic Low =
0, otherwise subtract the voltage drop of the device that drives this pin low.
6
LED4
Cathode of LED4 pin.
7
LED5
Cathode of LED5 pin.
8
C2N
This pin is the minus side of charge pump bucket capacitor C2. Connect a 1.0μF
ceramic capacitor between C2N and C2P.
9
EN
10
GND
Ground terminal pin.
11
C1N
This pin is the minus side of charge pump bucket capacitor C1. Connect a 1.0μF
ceramic capacitor between C1N and C1P.
12
NC
13
C2P
This pin is the plus side of charge pump bucket capacitor C2. Connect a 1.0μF
ceramic capacitor between C2N and C2P.
14
LED3
Cathode of LED3 pin.
15
VOUT
Charge pump output voltage pin, which connects to the anodes of all LEDs. A 1μF
capacitor to ground is recommended.
16
LED2
Cathode of LED2 pin.
Enable pin for both group drivers, active high.
Application Information
The CM9132 is a switched capacitor, charge pump
voltage converter ideally suited for driving white LEDs
to backlight LCD color displays in portable devices,
The CM9132 charge pump is the perfect driver for portable applications such as cellular phones, digital still
cameras, PDAs and any application where small
space, compact overall size, low system cost and minimal EMI are critical.
The CM9132 requires only two external switched
(bucket) capacitors, plus an input and an output capacitor, providing for a compact, low profile design. In
many applications, these can all be conveniently the
same value of 1.0μF, available in a compact 0805 surface mount package.
The adaptive conversion ratio selects the most efficient
operating mode. When Vin is higher than the needed
Vout (VLED+VCURRENT_SINK), the 1x mode is set.
When the input voltage is below the LED forward voltage and a voltage boost is needed, the 1.5x mode is
automatically selected. The 1.5x mode uses a fractional charge pump to convert the nominal Li-ion bat-
© 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
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04/26/06
PRELIMINARY
CM9132
Application Information (cont’d)
tery voltage (3.6V) by 1.5 times and regulates the LED
current to the five low dropout current sources.
VOUT
The current regulated sources maintain constant LED
drive in the presence of supply voltage fluctuations. All
LEDs within the group are driven with the same current
even when they have slightly different forward voltages.
The individual current sources sense the current
through each LED and match this current to typically
less than 2% for uniform brightness across the color
LCD display.
COUT
C1
½ VIN
VIN
C2
½ VIN
The CM9132 drives up to three WLEDS in group one
and two WLEDs in the second group. A typical second
group would be an outside caller ID display on a clamshell style cell phone. The maximum current programmed by RSET determines the maximum intensity
of each group’s display; the displays can be further
dimmed by PWM control applied to its ISET1 and
ISET2 pin.
Charge C1 and C2 to ½ VIN each
VOUT
C1
½ VIN
VIN
CM9132 Operation
When a voltage that exceeds the undervoltage lockout
threshold (UVLO) is applied to the VIN pin, the
CM9132 initiates a softstart cycle, typically lasting
100-S. Softstart limits the inrush current while the output capacitors are charged. Following softstart, the
CM9132 next determines the best conversion ratio (1x
or 1.5x).
The 1.5x mode employs a fractional charge pump. The
charge pump uses two phases from the internal oscillator to drive switches that are connected to the bucket
capacitors, C1 and C2, as shown in Figure 1. In the
first switch position, the bucket capacitors are connected in series and each are charged from Vin to a
voltage of Vin/2. The next phase changes the switch
positions so that C1 and C2 are in parallel, and places
them on top of VIN. The resulting voltage across COUT
is then; VIN+1/2VIN = 1.5 x VIN.
COUT
C2
½ VIN
Transfer ½ VIN charge to top of VIN
Figure 1. Switch Operation
The CM9132 has over-temperature and over-current
protection circuitry to limit device stress and failure during short circuit conditions. An overcurrent condition
will limit the output current (approximately
400~600-mA) and will cause the output voltage to
drop, until automatically resetting after removal of the
excessive current. Over-temperature protection disables the IC when the junction is about 135°C, and
automatically turns on the IC when the junction temperature drops by approximately 15°C.
Efficiency
A conventional charge pump with a fixed gain of 2x will
usually develop more voltage than is needed to drive
paralleled white LEDs from Li-Ion sources. This excessive gain develops a higher internal voltage, reducing
the system efficiency and increasing battery drain in
portable devices. A fractional charge pump with a gain
© 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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www.cmd.com
7
PRELIMINARY
CM9132
Application Information (cont’d)
of 1.5x is better suited for driving white LEDs in these
applications.
VLED=3.5V
90
The CM9132 charge pump automatically switches
between the two conversion gains, 1x and 1.5x, allowing high efficiency levels over a wide operating input
voltage range. The 1x mode allows the voltage to pass
directly through to the output when sufficient input voltage is available. As the battery discharges to the point
where any one current source no longer has sufficient
voltage headroom to maintain a constant current regulation, the 1.5x charge pump is enabled.
Efficiency (%)
1X
For an ideal 1.5x charge pump, IIN 1.5 x IOUT, and the
efficiency may be expressed as;
VOUT = ( VLED + VCURRENT _ SINK )
PLED ⎛ ( VOUT ) × IOUT
≈ ⎜⎜
PIN
⎝ VIN × 1.5 × IOUT
⎞
VOUT
⎟⎟ =
1
.
5 × VIN
⎠
For ( VLED + VCURRENT _ SINK ) = 3.9 V,
η≈
3.9 V
1.5 × VIN
Many charge pumps are fixed 2x designs. The ideal 2x
charge pump efficiency can be similarly expressed;
P OUT
3.9V ------------- ≈ ---------------------P IN
2.0 × V IN
In 1x mode, when the input voltage is above the output
voltage, the ideal efficiency is simply VOUT/VIN.
The typical conversion efficiency plots for these modes,
with some losses, are shown in Figure 2.
1X-1.5X
dual mode
60
45
1.5X
2X
30
3.0
At nominal loads, the switching losses and quiescent
current are negligible. If these losses are ignored for
simplicity, the efficiency, η, for an ideal 1.5x charge
pump can be expressed as the output power divided by
the input power:
P LED
η = -----------P IN
75
3.5
4.0
4.5
5.0
5.5
6.0
Input Voltage (V)
Figure 2. Ideal charge pump efficiency
As can be seen, the CM9132, with 1x and 1.5x modes,
has better efficiency in this application than a fixed 2x
charge pump. At low battery voltages, the higher efficiency of the CM9132 charge pump’s 1,5x gain
reduces the battery drain. At higher input voltages, typically seen when the system is running off an AC
adapter, the CM9132, operating the 1x mode, has better efficiency than single mode 1.5x or 2x charge
pumps, lowering the power dissipation for cooler circuit
operation and long life.
While the charge pump efficiency is easily determined,
the system efficiency is more difficult due to the current
source outputs, which complicate measuring the output
power. The forward voltage of the white LEDs will vary,
and the constant current sources will adjust to maintain
the current. When comparing systems, it is best to
compare the input current for a specified LED drive
current.
The 1x mode has better efficiency than the 1.5x mode.
Selecting LEDs with low forward voltage (VLED)
increases the time spent in the 1x mode as the battery
discharges, extending the battery run time.
Failed LED Detection
If a LED is shorted, the CM9132 will continue to operate and drive the remaining LEDs at the programmed
current. If a LED opens, the other LEDs will still be regulated at the programmed current.
© 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
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04/26/06
PRELIMINARY
CM9132
Application Information (cont’d)
LED Current Set (ISET)
The voltage at the ISET1 and ISET2 pins is provided
by a .66V bandgap reference. The LED current is
approximately 1000x the current set by the RSET resistor, according to the following formula:
Relative Luminous Intensity
1.5
Normalized to 20mA
External resistors program the reference current for
each group, setting the maximum driver current. These
resistors must be tied to a good analog ground. If it is
pulled to ground through a switch, for example, from
the host controller output, the voltage drop across the
switch should not exceed 10 mV.
1.0
0.5
0.0
0.66V – ( LogicLow )
R SET = ----------------------------------------------------- × 1000
I LED
0.0
5.0
10.0
15.0
20.0
25.0
30.0
Forward Current (mA)
Logic Low is the voltage on device driving this pin to
ground. If the resistor is tied to ground directly, Logic
low = 0. For 20mA LED current, RSET 33 k. When this
pin is driven high or open, the device will enter a sleep
mode with VOUT=4.5V and, with no load, IQUIESCENT =
500 A.
Analog Control of Display Intensity
Figure 3. Typical Luminous Intensity vs.
LED Current
The ISET pins of the CM9132 can be used to connect
an analog DC signal for analog dimming of the white
LEDs, as shown in Figure 4 This requires an additional
resistor, R, and a DC source voltage, Vc.
Typically, portable devices control the backlight display
intensity in response to ambient light conditions, or
lower the intensity after a short standby interval to converse battery charge. The luminous intensity of white
LEDs is proportional to the amount of forward current
through them, but the color wavelength emitted is also
dependent upon the forward current. In applications
where color shift is not critical, brightness can be controlled by adjusting the diode’s current. A typical white
LED Intensity vs. forward current curve is shown in
Figure 3.
VC
CM9132
R
ISET
R SET
Figure 4. Analog LED current adjust
A control voltage, Vc, applied to the resistor divider will
decrease the current for all LEDs. The maximum LED
current occurs with 0V on VC, which is set by Rp is the
parallel combination of R and RSET.
0.66V
R P = ----------------------- × 1000
I LED max
Choose the maximum control voltage, VC, which sets
zero LED current, and then determine the resistor ratio.
© 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
CM9132
Application Information (cont’d)
0.66V Ratio = ------------------------Vc – 0.66 V
CM9132
The resistors can be determined from the equations
below.
R
ISET
R × Ratio ) + RpR = (-----------------------------------------Ratio
55k
82.5k
Open Drain
Controller
Output
RSET
Rset = Ratio × R
Figure 6. Logic Signal Dimming
For example, a Vc max of 2.5V and a maximum current
setting of 20-mA, R=125-k, RSET=44.8-k. Figure 5
shows the control curve.
For example, to reduce the luminosity intensity by half,
using the LED curve from Figure 3, the current setting
needs to be changed from 20-mA to about 8-mA. The
values in Figure 6 will accomplish this, are where
obtained using the following equations;
LED Current vs. Vc
LED Current (mA)
25
20
Rp =
15
10
.66 V * 1000
ILED (max)
R=
5
0
0.0
0.5
1.0
1.5
2.0
Rset =
.66 V * 1000
ILED (min)
1
1
1
−
Rp Rset
Additional parallel resistors can be added in the same
way.
2.5
Control Voltage, Vc
Figure 5. LED Current Control Curve
PWM Control of Display Intensity
The circuit in Figure 6 is an example of logic dimming
control, which changes the LED forward current in discrete steps. The NMOS source is an open drain (or
open collector if bipolar) device, either the output of a
host controller, or a discrete device. Open drain, or
open collector devices sink current in their active, low
voltage state (logic 0), and are high impedance in their
high voltage, non-active state (logic 1). The open drain
must not be pulled high with an external resistor, but
instead connected only to the current setting resistors.
Typically, portable devices control the backlight display
intensity in response to ambient light conditions, or
lower the intensity after a short standby interval to converse battery charge. The CM9132 allows the each
output to lower the LED brightness independently by
applying a pulsing (PWM) signal to drive a switch connected in the RSET path to ground, as shown in
Figure 7 for group 2. The waveforms are shown in
Figure 8.
The white in white LEDs is typically bichromatic, produced by a blue or UV LED that excites yellow phosphors. The two colors combine and the human eye
sees these them as white light. The forward current of
the LED influences the chromaticity, with higher LED
current increasing the blue content of the color.
© 2006 California Micro Devices Corp. All rights reserved.
04/26/06
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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10
PRELIMINARY
CM9132
Application Information (cont’d)
Using a PWM signal allows the LEDs to be dimmed
without substantially shifting their color balance due to
chromaticity shifts related to changing white LED forward current. The PWM signal causes the group’s
LEDs to operate either at the full ISET current, or at
zero current. Only the time averaged current changes.
Above a minimum frequency, the human eye will perceive the change in duty cycle as a change in brightness.
The PWM signal will cause the average LED current to
be reduced. The average current is determined by the
PWM duty cycle, which can vary from 0% to 100%.
Decreased Duty Cycle will linearly lower the LED
brightness, 0% Duty Cycle will turn off the display
LEDs.
VBATT
on
VBATT
on
PWM Group2
off
R SET2
VIN
VOUT
ISET2
LED1
LED2
LED3
ISET1
Group1
on
off
R SET1
Enable
off
on
off
Display
Group1
LED4
LED5
RSET2
VOUT
ISET2
LED1
LED2
LED3
Display
Group1
LED4
LED5
Display
Group2
PWM
ISET1
CM9132
on
EN
RSET1
Enable
off
CM9132
EN
PWM
VIN
GND
Display
Group2
GND
Figure 9. Separate PWM signals for each group
CM9132 Design Examples
Figure 7. PWM applied to Group 2
Two-display cell phone
The recommended frequency is between 100 Hz and
200 Hz, with a duty cycle greater than 20%. If a frequency of less then 100 Hz is used, flicker might be
seen in the LEDs. The frequency should also be
greater than the refresh rate of the TFT display. Higher
frequencies will cause a loss of the brightness control
linearity. In addition, higher frequency can cause chromaticity shifts because the fixed rise and fall times of
the PWM signal will shift the forward current.
EN
VOUT
ILED (1,2,3)
ISET1
A typical application for the CM9132 is a two-display
clamshell phone, with an internal main display and an
external sub-display typically used for caller ID and
time of day, backlighting only when there is an incoming call. When the clamshell is opened, the sub-display
backlight goes off and the main display backlight goes
on. See Figure 10.
The either display’s intensity can be lowered by a
PWM signal applied to RSET resistors for the host controller, as determine by the ambient light conditions.
Group2
ILED (4,5)
Typically, the mobile phone LCD displays (both STN
and mini-TFT) require three to four white LEDs for
backlighting, but as few as two of the newer highbrightness LEDs can be used. Lightguides are used to
distribute the light uniformly behind the LCD. In this
application, three white LEDs are used for the larger
main display (inside the clamshell) and two for the subdisplay.
Low < 10 mV
ISET2
Figure 8. PWM Signal Dimming
© 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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11
PRELIMINARY
CM9132
Application Information (cont’d)
on
off
VBATT
PWM
VIN
or
Analog
on
Enable
Display 1
ISET2
RSET2
off
LED1
LED2
LED3
ISET1
CM9132
RSET1
on
VBATT
VOUT
Enable
EN
off
R SET2
MENU
R SET1
Sub
Display
LED4
LED5
GND
Main
Display
Caller ID
VOUT
ISET 2
LED1
LED2
LED3
ISET 1
CM9132
on
PDA
Display
LED4
LED5
EN
PWM
off
VIN
GND
Figure 10. Clamshell Phone Application
Figure 12. PDA Display Backlight
Phone with Keyboard Backlight
The CM9132 can support a wireless phone with LCD
and a backlit keyboard. Group one can drive the backlight to the LCD, and group two drives the lightguides
of the keyboard backlight. Each group can have a different current setting, and individual PWM signals
applied. One or both groups can have there brightness
controlled by a PWM signal. In the example in
Figure 11, both are controlled with one PWM signal.
VBATT
RSET2
R SET1
VIN
VOUT
ISET2
LED1
LED2
LED3
ISET1
PWM
The CM9132 can support a camera flash and a display
in digital still cameras as well as in camera equipped
smart phones and PDAs. A typical example would be
the main display is supplied by group 2, and the outputs of group 1 are used to support flash white LEDs.
In this case the flash LEDs are supplied 3 x 50-mA =
150-mA. See Figure 13. If less current is required for
the Main display drivers in group two, it can be allocated to group one with the appropriate programming
of the RSET resistors. See Figure 13.
Main
Display
MENU
CM9132
on
off
Camera Flash
EN
Enable
Display
on
LED4
LED5
VBATT
RSET2
off
Flash
GND
on
Figure 11. Phone with Keyboard Backlight
off
RSET1
Enable
VIN
ISET2
ISET1
VOUT
LED1
LED2
LED3
WLED
Flash
CM9132
LED4
LED5
EN
Main
Display
GND
PDA Backlight
The CM9132 can support larger displays such as color
LCDs for PDAs by utilizing both groups. Typically,
larger displays will require four or more WLED backlights. With all the drivers set at the same current, a
uniform backlighting can be achieved. EN can be used
for ON/OFF control PWM dimming. Figure 12 shows a
typical application.
Figure 13. Display and Flash Application
If a strong flash is needed, as in a DSC, both display
outputs can be used to drive flash modules, as shown
in Figure 14. In this case, EN controls the flash,
enabling both outputs.
© 2006 California Micro Devices Corp. All rights reserved.
12 490 N. McCarthy Blvd., Milpitas, CA 95035-5112
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04/26/06
PRELIMINARY
CM9132
Application Information (cont’d)
Capacitor Selection
VBATT
RSET2
VIN
VOUT
ISET2
LED1
LED2
LED3
ISET1
RSET1
For proper performance, use surface-mount, low ESR
ceramic capacitors for all four positions. X7R or X5R
ceramic dielectric provides good stability over the operating temperature and voltage range.
WLED
Flash
The capacitance and ESR of the external bucket
capacitors will directly affect the output impedance and
efficiency of the converter. A ceramic 1-µF capacitor is
recommended.
CM9132
Flash
LED4
LED5
EN
WLED
Flash
GND
Figure 14. All Flash
Another option, which provides the maximum flash current, can be implemented by pulling the cathode of the
flash LED to ground with a switch for the brief duration
of the flash. The example shown in Figure 15 shows an
example that allows the flash LED to be used as a
torch light or a preview light in normal operation, and
for full flash when the external switch is turned on. In
this example, the main display intensity is controlled by
two line inputs to ISET1, and the torch light is controlled by S1.
VBATT
VIN
EN2
EN1
LED1
LED2
LED3
CM9132
ISET1
66K
33K
VOUT
15K
ISET2
RSET2
S1
GND
LED4
LED5
Main
Display
MENU
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. Much of the ripple voltage is due to moving current charge in and out of the capacitor and the capacitor’s impedance at the charge pump frequency. If ripple
voltage or current on the battery bus is an application
issue, add a small input inductor between the battery
and the capacitor, or just increase the capacitor.
For a given output current, increasing the output
capacitance reduces output ripple in the 1.5x mode.
Increasing the output capacitor will also increase startup current and time. 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.
Layout Guide
Flash/Torch
Photo Flash
Figure 15. Display, Torch and Full Flash
The charge pump is rapidly charging and discharging
the external capacitors, so external traces to the
capacitors should be made wide and short to minimize
inductance and high frequency ringing. The four
capacitors should be located as close as practical to
the charge pump, particularly C1 and C2, which have
the highest dv/dt. Use a solid ground plane, and connect the ground side of Cin, Cout and the package
GND as close as practical.
© 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
13
PRELIMINARY
CM9132
Mechanical Details
TQFN-16 Mechanical Specifications
Mechanical Package Diagrams
The CM9132 is supplied in a 16-lead, 4.0mm x 4.0mm
TQFN package. Dimensions are presented below.
For complete information on the TQFN16, see the California Micro Devices TQFN 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
14