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PRELIMINARY CM9132 Two Group, 3 and 2, WLED Driver, Different Current Settings
Features
* * * * * * * * * * * * * * * * * * 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-A 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
Product Description
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. 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-A. 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.
Applications
* * * * Drive white LEDs for STN/TFT Color LCD backlighting Cell phones, PDAs with multiple displays Digital Still Cameras Flash for DSC
Typical Application
1.0uF C1P C1N VIN 1uF 1.0uF C2P C2N VOUT LED1 EN ISET1 ISET2 GND
Display 1
2.9V to 6.0V
1uF
off
on
Enable
PhotonICTMLED2 CM9132
LED3 LED4 LED5
Display 2
RSET1
RSET2
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PRELIMINARY CM9132
Package Pinout
PACKAGE / PINOUT DIAGRAM
Bottom View
5 ISET2 6 LED4 7 LED5 8 C2N
ISET1 VIN C1P LED1
4 3 2 1 16 15 14 13
9 EN
TQFN16 4X4
10 GND 11 C1N 12 NC
LED3
LED2
16-Lead TQFN Package (4mm x 4mm)
Note: This drawing is not to scale.
Ordering Information
PART NUMBERING INFORMATION
Lead-free Finish Leads 16 Package TQFN Ordering Part Number1 CM9132-01QE Part Marking
Note 1: Parts are shipped in Tape & Reel form unless otherwise specified.
Specifications
ABSOLUTE MAXIMUM RATINGS
PARAMETER ESD Protection (HBM ) Pin Voltages VIN to GND VOUT to GND ISET1, ISET2, EN to GND All other pins to GND Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering, 10s) RATING 2 [GND - 0.3] to +6.0 [GND - 0.3] to +7.0 [GND - 0.3] to +5.0 [GND - 0.3] to +5.0 -65 to +150 -40 to +85 300 UNITS kV V V V V C C C
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VOUT
C2P
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PRELIMINARY CM9132
Specifications (cont'd)
ELECTRICAL OPERATING CHARACTERISTICS
VIN = 3.6V; All outputs are on. Typical values are at TA = 25C. SYMBOL VIN VUVLO IQ ISD PARAMETER Supply Voltage Range Undervoltage Lockout Quiescent Current Shutdown Supply Current All outputs are no load. 1x mode VEN < 0.4V IOUT = 0mA to 120mA, VIN = 3.0 to 5.5V 4.2 CONDITIONS MIN 2.9 1.7 1.8 500 2 10 5.5 300 1 2 5 50 1.8 0.4 400 135 15 mA C C TYP MAX 6.0 1.9 UNIT S V V A A V mA % % mA
VOUT Charge Pump Output Voltage VOUT ILED TOT ILED Accuracy of ISET Matching current between LED1 to LED3 ILED per driver EN, ISET(1,2) VIH VIL Protection Over-current Limit Over-temperature Limit Over-temperature Hysteresis High Level Input Voltage Low Level Input Voltage Total ILED Current
ILED1 thru ILED3+photoflash
VIN = 3.0V to 5.5V VIN = 4.0V, ILED 1,2,3 = 20mA Device total ILED < 150mA
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PRELIMINARY CM9132
Typical Performance Curves
Charge Pump Efficiency
Vled=3.2V 100 200
Source Current
Vled=3.2V
Efficiency (%)
90
Input Current (mA)
175 150 125 100 75 50 25 3.0
Iout=60mA Iout=30mA Iout=120mA
80
Iout=120mA Iout=30mA Iout=60mA
70
60 3.0
3.5
4.0
4.5
5.0
5.5
6.0
3.5
4.0
4.5
5.0
5.5
6.0
Input Voltage (V)
Input Voltage (V)
Typical Waveforms
Cin=C2=C3=Cout=1uF, Iout=120mA 100 mV/ div 20mA/ div 100 mV/ div
Typical Waveforms
Cin=C2=C3=Cout=1uF, Iout=120mA
Vout
Vout
Iin
20mA/ div
Iin
50mV/ div 1.0x mode 1us/div
Vin
50mV/ div 1.5x mode 1us/div
Vin
Startup
Cin=C2=C3=Cout=1uF, Iout=120mA
25
LED Current vs. Vin
LED Current (mA)
1V/ div
EN
20
200mA/ div 2V/ div .5ms/div
15
Iin
10
Vout
5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Input Voltage (V)
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PRELIMINARY CM9132
Functional Block Diagram
C1P C1N C2P C2N
VIN
OSC 500 KHz
Charge Pump x1, x1.5
VOUT
UVLO
Bandgap
LED1
Mode Select
LED2 Current Sinks LED3 LED4 LED5
EN
Failed LED Condition
CM9132
GND ISET1 ISET2
Pin Descriptions
PIN DESCRIPTIONS
LEAD(s) NAME DESCRIPTION
1 2 3
LED1 C1P VIN
Cathode of LED1 pin. This pin is the plus side of charge pump bucket capacitor C1. Connect a 1.0-F ceramic capacitor with a voltage rating of 10 V or greater between C1N and C1P. Positive supply voltage input pin. This voltage should be between 2.9V and 6V. This pin requires a 1.0-F 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 = ---------------------------------------------------- x 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.
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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 = ---------------------------------------------------- x 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 7 8 9 10 11 12 13 14 15 16 LED4 LED5 C2N EN GND C1N NC C2P LED3 VOUT LED2 This pin is the plus side of charge pump bucket capacitor C2. Connect a 1.0F ceramic capacitor between C2N and C2P. Cathode of LED3 pin. Charge pump output voltage pin, which connects to the anodes of all LEDs. A 1F capacitor to ground is recommended. Cathode of LED2 pin. Cathode of LED4 pin. Cathode of LED5 pin. This pin is the minus side of charge pump bucket capacitor C2. Connect a 1.0F ceramic capacitor between C2N and C2P. Enable pin for both group drivers, active high. Ground terminal pin. This pin is the minus side of charge pump bucket capacitor C1. Connect a 1.0F ceramic capacitor between C1N and C1P.
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
(c) 2006 California Micro Devices Corp. All rights reserved.
many applications, these can all be conveniently the same value of 1.0F, 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-
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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. 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. 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.
C1 1/2 VIN
VOUT
COUT
VIN
C2 1/2 VIN
Charge C1 and C2 to 1/2 VIN each VOUT
C1 COUT
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.
VIN
1/2 VIN
C2 1/2 VIN
Transfer 1/2 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 135C, and automatically turns on the IC when the junction temperature drops by approximately 15C.
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
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PRELIMINARY CM9132
Application Information (cont'd)
of 1.5x is better suited for driving white LEDs in these applications. 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. At nominal loads, the switching losses and quiescent current are negligible. If these losses are ignored for simplicity, the efficiency, , for an ideal 1.5x charge pump can be expressed as the output power divided by the input power:
P LED = -----------P IN
90 1X
VLED=3.5V
Efficiency (%)
75 60 45
1X-1.5X dual mode
2X
30 3.0 3.5 4.0 4.5
1.5X
5.0
5.5
6.0
Input Voltage (V)
Figure 2. Ideal charge pump efficiency
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 ) x IOUT V x 1.5 x I PIN OUT IN VOUT = 1.5 x V IN 3.9 V 1.5 x VIN
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.
For ( VLED + VCURRENT _ SINK ) = 3.9 V,
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 x 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.
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.
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PRELIMINARY CM9132
Application Information (cont'd)
LED Current Set (ISET)
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. 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:
0.66V - ( LogicLow ) R SET = ---------------------------------------------------- x 1000 I LED Relative Luminous Intensity
1.5
Normalized to 20mA
1.0
0.5
0.0 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.
Figure 3. Typical Luminous Intensity vs. LED Current
Analog Control of Display Intensity
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.
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.
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 = ---------------------- x 1000 I LED max
Choose the maximum control voltage, VC, which sets zero LED current, and then determine the resistor ratio.
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PRELIMINARY CM9132
Application Information (cont'd)
0.66V Ratio = ------------------------Vc - 0.66 V
The resistors can be determined from the equations below.
R = ( R x Ratio ) + Rp -----------------------------------------Ratio Rset = Ratio x R
CM9132 R ISET 55k 82.5k RSET Open Drain Controller Output
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.
LED Current vs. Vc
25
Figure 6. Logic Signal Dimming
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;
Rp = .66 V * 1000 ILED (max) 1 1 1 - Rp Rset Rset = .66 V * 1000 ILED (min)
LED Current (mA)
20 15 10 5 0 0.0 0.5 1.0 1.5 2.0 2.5
R=
Control Voltage, Vc
Additional parallel resistors can be added in the same way.
Figure 5. LED Current Control Curve
PWM Control of Display Intensity
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.
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.
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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.
VBATT VIN
on off
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 off
VIN ISET2
VOUT LED1 LED2 LED3 Display Group1
PWM PWM
on
VOUT LED1 LED2 LED3 Display Group1
on off
RSET2
PWM Group2
R SET2 R SET1
ISET2 ISET1
RSET1 Enable
ISET1 CM9132 EN GND
Group1
on off
CM9132 LED4 LED5 Display Group2
off
LED4 LED5
Display Group2
Enable
EN GND
Figure 9. Separate PWM signals for each group
Figure 7. PWM applied to Group 2
CM9132 Design Examples
Two-display cell phone
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. 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.
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
Group2 ILED (4,5)
Low < 10 mV
ISET2
Figure 8. PWM Signal Dimming
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PRELIMINARY CM9132
Application Information (cont'd)
on off
PWM
VBATT VIN
RSET2
or Analog Enable Display 1
ISET2
VOUT LED1 LED2 LED3 Main Display
MENU
VBATT R SET2 R SET1
on off
VIN ISET 2 ISET 1
VOUT LED1 LED2 LED3
on off
RSET1 on off
ISET1 CM9132 EN GND
Enable
CM9132 EN GND LED4 LED5
PDA Display
LED4 LED5
Sub Display
Caller ID
PWM
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
on off
Camera Flash
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.
Enable Display VBATT RSET2 Flash RSET1
VIN ISET2 ISET1
VOUT LED1 LED2 LED3 Main Display
MENU
CM9132 EN GND LED4 LED5
off
VIN ISET2 ISET1
VOUT LED1 LED2 LED3 WLED Flash
on
PWM
CM9132 EN GND LED4 LED5 Main Display
on
Enable
Figure 11. Phone with Keyboard Backlight
off
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.
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PRELIMINARY CM9132
Application Information (cont'd)
Capacitor Selection
VBATT RSET2 VIN ISET2 ISET1 VOUT LED1 LED2 LED3 LED4 LED5 WLED Flash
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. The capacitance and ESR of the external bucket capacitors will directly affect the output impedance and efficiency of the converter. A ceramic 1-F capacitor is recommended. 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.
RSET1 Flash
CM9132 EN GND WLED Flash
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 66K 33K
VOUT Main Display
MENU Flash/Torch
ISET1
LED1 LED2 LED3 CM9132 LED4 LED5
15K RSET2 S1
ISET2 GND
Layout Guide
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.
Photo Flash
Figure 15. Display, Torch and Full Flash
(c) 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 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. Mechanical Package Diagrams
D
PACKAGE DIMENSIONS
Leads Dim. A A1 A3 b D D1 D2 E E1 E2 e L # per tube # per tape and reel 0.55 2.05 0.65 TYP. 0.65 0.022 xx pieces* xxxx pieces
E2
16 Millimeters Min 0.00 0.20 REF 0.25 4.0 BSC 1.95 REF 2.05 4.0 BSC 1.95 REF 2.15 0.081 0.026 0.026
D1
E
Package
QFN-16 (4x4) Inches Max 0.84 0.04 0.33 0.00 .008 0.010 0.157 0.077 2.15 0.081 0.157 0.077 0.085 0.085 0.013 Min Nom 0.031 Max 0.033 0.002
Pin 1 Marking
Nom 0.80
0.15 C 0.15 C
TOP VIEW
0.10 C
0.08 C
SIDE VIEW
A3 A1
A
Controlling dimension: millimeters
* This is an approximate number which may vary.
E1
D2 L
DAP SIZE 1.8 X 1.8
e
b
16X 0.10
M
CAB
BOTTOM VIEW
Package Dimensions for 16-Lead TQFN
(c) 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

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