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LTC3202 Low Noise, High Efficiency Charge Pump for White LEDs
FEATURES
s s s s s s s s s s s
DESCRIPTIO
Low Noise Constant Frequency Operation 25% Less Input Current Than Doubler Charge Pump High Output Current: Up To 125mA Small Application Circuit Regulated Output Voltage or Current Automatic Soft-Start VIN Range: 2.7V to 4.5V No Inductors 1.5MHz Switching Frequency ICC < 1A in Shutdown Available in 10-Pin MSOP and 3mm x 3mm DFN Packages
The LTC(R)3202 is a low noise, constant frequency charge pump DC/DC converter that uses fractional conversion to increase efficiency in white LED applications. The part can be used to produce a regulated voltage or current of up to 125mA from a 2.7V to 4.5V input. Low external parts count (two flying capacitors and two small bypass capacitors at VIN and VOUT) make the LTC3202 ideally suited for small, battery-powered applications. An internal 2-bit DAC allows LED current to be adjusted for LED brightness control. The LTC3202 also has thermal shutdown protection and can survive a continuous shortcircuit from VOUT to GND. Built-in soft-start circuitry prevents excessive inrush current during start-up. High switching frequency enables the use of small external capacitors. A low current shutdown feature disconnects the load from VIN and reduces quiescent current to less than1A. The LTC3202 is available in the 10-pin MSOP and 3mm x 3mm DFN packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s s
White LED Backlighting Programmable Boost Current Source
TYPICAL APPLICATIO
C2 1F C3 1F
Programmable White LED Power Supply Input and Output Ripple
VIN (AC COUPLED) 20mV/DIV
8 C1+ 10 CURRENT PROGRAMMING VIN 3V TO 4.5V C1 1F 1 4 D0 D1 VIN
7 C1-
0mA TO 125mA C2+ C2- 3 TOTAL CURRENT VOUT
9
6
LTC3202 FB GND 5, 11 2 C4 1F 36 36 36 36 36 36
VOUT (AC COUPLED) 20mV/DIV 500ns/DIV VIN = 3.6V CIN = COUT = 1F IOUT = 60mA
3202 G09
C1, C2, C3, C4 = MURATA GRM 39X5R105K6.3 OR TAIYO YUDEN JMK107BJ105MA
3202 TA01
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1
LTC3202
ABSOLUTE
AXI U RATI GS
VIN, VOUT to GND ......................................... -0.3V to 6V D0, D1 ............................................. -0.3V to VIN + 0.3V VOUT Short-Circuit Duration ............................. Indefinite IOUT (Note 2)....................................................... 150mA
PACKAGE/ORDER I FOR ATIO
TOP VIEW D1 1 FB 2 VOUT 3 VIN 4 GND 5 10 9 8 7 6 D0 C2+ C1+ C1 - C2 -
ORDER PART NUMBER LTC3202EMS MS PART MARKING LTWL
MS PACKAGE 10-LEAD PLASTIC MSOP TJMAX = 150C, JA = 120C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 3.3V unless otherwise noted.
PARAMETER Input Power Supply VIN Operating Voltage ICC Operating Current ISHDN Shutdown Current Feedback Pin Set Points 0.2V Setting Feedback Voltage 0.4V Setting Feedback Voltage 0.6V Setting Feedback Voltage IFB Charge Pump ROL Open Loop Output Impedance (1.5VIN - VOUT)/IOUT VOUT Load Regulation (VOUT/IOUT) CLK Frequency D0, D1 High Level Input Voltage (VIH) Low Level Input Voltage (VIL) Input Current (IIH) Input Current (IIL) DO, D1 = VIN DO, D1 = 0V
q q q q q
ELECTRICAL CHARACTERISTICS
CONDITIONS
IOUT = 0mA, VOUT = 3.6V, VIN = D0 = D1 = 4.5V VOUT = 0V D0 = 1, D1 = 0, IOUT = 0mA, VIN = 3.6V D0 = 0, D1 = 1, IOUT = 0mA, VIN = 3.6V D0 = 1, D1 = 1, IOUT = 0mA, VIN = 3.6V VFB = 0.8V VIN = 3.3V, VOUT = 4.4V, VFB = 0 IOUT = 10mA to 90mA, VFB/VOUT = 1
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Based on long-term current density limitations.
2
U
U
W
WW U
W
(Note 1)
Operating Temperature Range (Note 3) ...-40C to 85C Storage Temperature Range ..................-65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
TOP VIEW D1 FB VOUT VIN SGND 1 2 3 4 5 11 10 D0 9 C2+ 8 C1+ 7 C1- 6 C2-
ORDER PART NUMBER LTC3202EDD DD PART MARKING LABB
DD PACKAGE 10-LEAD (3mm x 3mm) PLASTIC DFN TJMAX = 150C, JA = 44C/W, JC = 3C/W EXPOSED PAD IS PGND (PIN 11) MUST BE CONNECTED TO GROUND PLANE
MIN 2.7
TYP
MAX 4.5
UNITS V mA A mV mV mV nA mV/mA MHz V
q q
2.5
5 1
q q q q
188 380 570 -50
200 400 600
212 420 630 50
q
4.5 0.35 1.5 1.3
6
0.4 -1 -1 1 1
V A A
Note 3: The LTC3202E is guaranteed to meet performance specifications from 0C to 70C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with statistical process controls.
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LTC3202 TYPICAL PERFOR A CE CHARACTERISTICS
VFB Set Point vs Input Supply (200mV Setting)
0.21 ILOAD = 20A VD0 = VIN VD1 = 0V SET POINT (V) TA = 85C 0.20 TA = 25C
SET POINT (V)
0.19
2.7
3.0
3.3 3.6 3.9 INPUT SUPPLY (V)
VFB Set Point vs Input Supply (600mV Setting)
0.63 ILOAD = 60A VD0 = VD1 = VIN
0.8 0.7
FEEDBACK VOLTAGE (V)
SET POINT (V)
TA = 25C, 85C 0.60 TA = -40C
0.57
2.7
3.0
3.3 3.6 3.9 INPUT SUPPLY (V)
Input Current vs Load Current
160 140
INPUT CURRENT (mA)
OSCILLATOR FREQUENCY (MHz)
VIN = 3.6V CIN = COUT = CFLY1 = CFLY2 = 1F TA = 25C
120 100 80 VOUT = 4V 60 40 20 0 0 VOUT = 4.5V
20
80 60 LOAD CURRENT (mA)
UW
40
VFB Set Point vs Input Supply (400mV Setting)
0.42 ILOAD = 40A VD0 = 0V VD1 = VIN TA = 25C TA = 85C 0.40 TA = -40C
TA = -40C
4.2
4.5
3202 G01
0.38
2.7
3.0
3.3 3.6 3.9 INPUT SUPPLY (V)
4.2
4.5
3202 G02
VFB vs Load Current
VD0 = VD1 = VIN CIN = COUT = CFLY1 = CFLY2 = 1F VOUT - VFB = 3.4V TA = 25C VIN = 3.2V VIN = 3V
0.6 0.5 0.4 0.3 0.2
4.2
4.5
3202 G03
0
25
50 75 100 LOAD CURRENT (mA)
125
150
3202 G04
Oscillator Frequency vs Supply Voltage
1.9
1.7
TA = -40C TA = 25C TA = 85C
1.5
1.3
1.1
0.9
100
3202 G05
2.7
3.0
3.3 3.6 3.9 SUPPLY VOLTAGE (V)
4.2
4.5
3202 G06
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LTC3202 TYPICAL PERFOR A CE CHARACTERISTICS
Short-Circuit Current vs Supply Voltage
300 280 CFLY = 1F VFB = 0V VOUT = 0V TA = 25C
OUTPUT CURRENT (mA)
VOUT Soft-Start Ramp
VIN (AC COUPLED) 20mV/DIV
VD0, D1 2V/DIV
VOUT 1V/DIV
VIN = 3.6V COUT = 1F
PI FU CTIO S
D1, D0 (Pin 1, 10): Control Inputs. D0 and D1 determine the set point voltage of the FB pin (see Table 1). FB (Pin 2): FB is the Feedback Input for the Regulation Control Loop. VOUT (Pin 3): VOUT is the Output of the Charge Pump. A low impedance 1F X5R or X7R ceramic capacitor is required from VOUT to GND. VIN (Pin 4): Input Supply Voltage. VIN should be bypassed with a 1F to 4.7F low impedance ceramic capacitor. GND (Pin 5): Ground for the Charge Pump and Control Circuitry. This pin should be connected directly to a low impedance ground plane. C2-, C1-, C1+, C2 + (Pin 6, 7, 8, 9): Charge Pump Flying Capacitor Pins. A 1F X5R or X7R ceramic capacitor should be connected from C1+ to C1- and from C2+ to C2 -. PGND (Pin 11, Exposed Pad DFN Only): Power Ground for the Charge Pump. This pin must be connected directly to a low impedance ground plane.
4
UW
260 240 220 200 180
2.7
3.0
3.3 3.6 3.9 INPUT SUPPLY (V)
4.2
4.5
3202 G07
Input and Output Ripple
VOUT (AC COUPLED) 20mV/DIV
200s/DIV
3202 G08
500ns/DIV VIN = 3.6V CIN = COUT = 1F IOUT = 60mA
3202 G09
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LTC3202
SI PLIFIED BLOCK DIAGRA
FB 2
VIN 4 7 C1-
VOUT 3 9
W
-
10 D0 2-BIT DAC
+
W
1 D1
SOFT-START AND SHUTDOWN CONTROL
1.5MHz OSCILLATOR
8 C1+
C2+
6
C2-
3202 BD
5, 11 GND
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LTC3202
OPERATIO
The LTC3202 uses a fractional conversion switched capacitor charge pump to boost VOUT to as much as 1.5 times the input voltage. A two-phase nonoverlapping clock activates the charge pump switches. On the first phase of the clock the flying capacitors are charged in series from VIN. On the second phase of the clock they are connected in parallel and stacked on top of VIN. This sequence of charging and discharging the flying capacitors continues at a free running frequency of 1.5MHz (typ). Regulation is achieved by sensing the voltage at the FB pin and modulating the charge pump strength based on the error signal. The control pins, D0 and D1, program the set point of the internal digital-to-analog converter. The regulation loop will increase VOUT until FB comes to balance at the set-point voltage. Table 1 shows the regulation voltage as a function of D0 and D1.
Table 1. Feedback Control Voltage Settings
D1 0 0 1 1 D0 0 1 0 1 Feedback Set Point Voltage Shutdown 0.2V 0.4V 0.6V
In shutdown mode all circuitry is turned off and the LTC3202 draws only leakage current from the VIN supply. Furthermore, VOUT is disconnected from VIN. The D0 and D1 pins are CMOS inputs with a threshold voltage of approximately 0.8V. The LTC3202 is in shutdown when a logic low is applied to both D0 and D1. Since the D0 and D1 pins are high impedance CMOS inputs they should never be allowed to float. To ensure that their states are defined they must always be driven with valid logic levels. Shutdown Current Output voltage detection circuitry will draw a current of 5A when the LTC3202 is in shutdown. This current will be eliminated when the output voltage (VOUT) is at 0V. To ensure that VOUT is at 0V in shutdown a bleed resistor can be used from VOUT to GND. 10k to 100k is acceptable. Short-Circuit/Thermal Protection The LTC3202 has built-in short-circuit current limiting as well as over temperature protection. During short-circuit
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(Refer to Simplified Block Diagram)
conditions it will automatically limit its output current to approximately 250mA. At higher temperatures, or if the input voltage is high enough to cause excessive self heating on-chip, thermal shutdown circuitry will shut down the charge pump when the junction temperature exceeds approximately 160C. It will reenable the charge pump once the junction temperature drops back to approximately 155C. The LTC3202 will cycle in and out of thermal shutdown indefinitely without latchup or damage until the short-circuit on VOUT is removed. Soft-Start To prevent excessive current flow at VIN during start-up, the LTC3202 has built-in soft-start circuitry. Soft-start is achieved by increasing the amount of current available to the output charge storage capacitor linearly over a period of approximately 500s. The soft-start feature activates any time an input, D0 or D1, changes state. This will prevent large inrush current during initial start-up as well as when the feedback setting is changed from one value to the next. Note that the set point voltage will drop to zero during the soft-start period. Under heavy load conditions there may be observable droop at VOUT until the soft-start circuit catches up. Programming the LTC3202 for Voltage or Current The LTC3202 can be configured to control either a voltage or a current. In white LED applications the LED current is programmed by the ratio of the feedback set point voltage and a sense resistor as shown in Figure 1. The current of the remaining LEDs is controlled by virtue of their similarity to the reference LED and the ballast voltage across the sense resistor.
3 VOUT LTC3202 FB GND 5, 11 2 1F RX *** RX ILED = VFB RX
3202 F01
Figure 1. Current Control Mode
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LTC3202
OPERATIO
In this configuration the feedback factor (VFB/VOUT) will be very near unity since the small signal LED impedance will be considerably less than the current setting resistor RX. Thus, this configuration will have the highest loop gain giving it the lowest closed-loop output resistance. Likewise it will also require the largest amount of output capacitance to preserve stability. For fixed voltage applications, the output voltage can be set by the ratio of two resistors and the feedback control voltage as shown in Figure 2. The output voltage is given by the set point voltage times the gain factor 1 + R1/R2. Note that the closed-loop output resistance will increase in proportion to the loop gain consumed by the resistive divider ratio. For example, if the resistor ratio is 2:1 giving a gain of 3, the closed-loop output resistance will be about 3 times higher than its nominal gain of 1 value. Given that the closed-loop output resistance is about 0.35 with a gain of 1, the closed-loop output resistance will be about 1 when using a gain of 3.
3 VOUT = VFB (1 + R1 ) R2
VOUT LTC3202 FB GND 5, 11
3202 F02
OUTPUT RESISTANCE ()
Figure 2. Voltage Control Mode
When using the LTC3202 in voltage control mode, any of the three voltage settings (0.2V, 0.4V or 0.6V) can be used as the set point voltage. For optimum noise performance and lowest closed-loop output resistance the highest voltage setting will likely be the most desirable. Typical values for total voltage divider resistance can range from several ks up to 1M.
U
(Refer to Simplified Block Diagram)
Charge Pump Strength Figure 3 shows how the LTC3202 can be modeled as a Thevenin equivalent circuit to determine the amount of current available from the effective input voltage, 1.5VIN and the effective open-loop output resistance, ROL.
ROL
+
VOUT
+ -
1.5VIN
-
3202 F03
Figure 3. Equivalent Open-Loop Circuit
From Figure 3 the available current is given by: IOUT = 1.5VIN - VOUT ROL
Typical values of ROL as a function of temperature are shown in Figure 4.
4.8 VFB = 0 IL = 100mA C1 = C2 = 1F ROL = (1.5VIN - VOUT)/IL
R1 2 1F R2
4.6
4.4 VIN = 2.7V 4.2 VIN = 3.6V 4.0
3.8 -40
-15
35 10 TEMPERATURE (C)
60
85
3202 F04
Figure 4. Typical ROL vs Temperature
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LTC3202
OPERATIO
ROL is dependent on a number of factors including the switching term, 1/(2fOSC CFLY), internal switch resistances and the nonoverlap period of the switching circuit. However, for a given ROL, the amount of current available will be directly proportional to the advantage voltage 1.5VIN - VOUT. This voltage can typically be quite small. Consider the example of driving white LEDs from a 3.1V supply. If the LED forward voltage is 3.8V and the 0.6V VFB setting is used, the advantage voltage is 3.1V * 1.5V - 3.8V - 0.6V or only 250mV. However if the input voltage is raised to 3.2V the advantage voltage jumps to 400mV--a 60% improvement in available strength! Note that a similar improvement in advantage voltage can be achieved by operating the LTC3202 at a lower voltage setting such as the 0.4V setting. VIN, VOUT Capacitor Selection The style and value of capacitors used with the LTC3202 determine several important parameters such as regulator control loop stability, output ripple, charge pump strength and minimum start-up time. To reduce noise and ripple, it is recommended that low equivalent series resistance (ESR) ceramic capacitors be used for both CIN and COUT. Tantalum and aluminum capacitors are not recommended because of their high ESR. The value of COUT directly controls the amount of output ripple for a given load current. Increasing the size of COUT will reduce the output ripple at the expense of higher minimum turn-on time and higher start-up current. The peak-to-peak output ripple is approximately given by the expression:
VRIPPLEP- P
Where fOSC is the LTC3202's oscillator frequency (typically 1.5MHz) and COUT is the output charge storage capacitor. Both the style and value of the output capacitor can significantly affect the stability of the LTC3202. As shown
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in the block diagram, the LTC3202 uses a control loop to adjust the strength of the charge pump to match the current required at the output. The error signal of this loop is stored directly on the output charge storage capacitor. The charge storage capacitor also serves to form the dominant pole for the control loop. To prevent ringing or instability, it is important for the output capacitor to maintain at least 0.6F of capacitance over all conditions. Likewise, excessive ESR on the output capacitor will tend to degrade the loop stability of the LTC3202. The closedloop output resistance of the LTC3202 is designed to be 0.35. For a 100mA load current change, the feedback voltage will change by about 35mV. If the output capacitor has 0.35 or more of ESR the closed-loop frequency response will cease to roll-off in a simple one-pole fashion and poor load transient response or instability could result. Multilayer ceramic chip capacitors typically have exceptional ESR performance and combined with a tight board layout should yield very good stability and load transient performance. As the value of COUT controls the amount of output ripple, the value of CIN controls the amount of ripple present at the input pin (VIN). The input current to the LTC3202 will be relatively constant while the charge pump is on either the input charging phase or the output charging phase but will drop to zero during the clock nonoverlap times. Since the nonoverlap time is small (~25ns) these missing "notches" will result in only a small perturbation on the input power supply line. Note that a higher ESR capacitor such as tantalum will have higher input noise due to the input current change times the ESR. Therefore ceramic capacitors are again recommended for their exceptional ESR performance. Further input noise reduction can be achieved by powering the LTC3202 through a very small series inductor as shown in Figure 5. A 10nH inductor will reject the fast current notches, thereby presenting a nearly constant current load to the input power supply. For economy the 10nH inductor can be fabricated on the PC board with about 1cm (0.4") of PC board trace.
IOUT 3 fOSC * C OUT
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LTC3202
OPERATIO
VIN
Figure 5. 10nH Inductor Used for Input Noise Reduction
Flying Capacitor Selection
Warning: A polarized capacitor such as tantalum or aluminum should never be used for the flying capacitors since their voltage can reverse upon start-up of the LTC3202. Ceramic capacitors should always be used for the flying capacitors.
The flying capacitor controls the strength of the charge pump. In order to achieve the rated output current it is necessary to have at least 0.7F of capacitance for each of the flying capacitors. Capacitors of different materials lose their capacitance with higher temperature and voltage at different rates. For example, a ceramic capacitor made of X7R material will retain most of its capacitance from -40C to 85C whereas a Z5U or Y5V style capacitor will lose considerable capacitance over that range. Z5U and Y5V capacitors may also have a very poor voltage coefficient causing them to lose 60% or more of their capacitance when the rated voltage is applied. Therefore, when comparing different capacitors it is often more appropriate to compare the amount of achievable capacitance for a given case size rather than comparing the specified capacitance value. For example, over rated voltage and temperature conditions, a 1F, 10V, Y5V ceramic capacitor in a 0603 case may not provide any more capacitance than a 0.22F, 10V, X7R available in the same 0603 case. The capacitor manufacturer's data sheet should be consulted to determine what value of capacitor is needed to ensure minimum capacitances at all temperatures and voltages. Table 2 shows a list of ceramic capacitor manufacturers and how to contact them:
U
10nH 4 1F 5, 11
Table 2 Recommended Capacitor Vendors
VIN LTC3202 GND
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AVX Kemet Murata Taiyo Yuden Vishay
www.avxcorp.com www.kemet.com www.murata.com www.t-yuden.com www.vishay.com
0.1F
For very light load applications the flying capacitor may be reduced to save space or cost. The theoretical minimum output resistance of a 2:3 fractional charge pump is given by: ROL(MIN) 1.5VIN - VOUT IOUT = 1 2f0SCCFLY
Where fOSC is the switching frequency (1.5MHz typ) and CFLY is the value of the flying capacitors. Note that the charge pump will typically be weaker than the theoretical limit due to additional switch resistance, however for very light load applications the above expression can be used as a guideline in determining a starting capacitor value. Power Efficiency The power efficiency () of the LTC3202 is similar to that of a linear regulator with an effective input voltage of 1.5 times the actual input voltage. This occurs because the input current for a 2:3 fractional charge pump is approximately 1.5 times the load current. In an ideal regulating 2:3 charge pump the power efficiency would be given by: IDEAL POUT = VOUT * IOUT = VOUT 3 PIN VIN * IOUT 1.5VIN 2 At moderate to high output power the switching losses and quiescent current of the LTC3202 are negligible and the expression above is valid. For example with VIN = 3.2V, IOUT = 80mA and VOUT regulating to 4.2V the measured efficiency is 82% which is just under the theoretical 87.5% calculation.
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LTC3202
OPERATIO
Layout Considerations Due to its high switching frequency and the transient currents produced by the LTC3202, careful board layout is necessary. A true ground plane and short connections to all capacitors will improve performance and ensure proper regulation under all conditions. Figure 6 shows the recommended layout configurations. The flying capacitor pins C1+, C2+, C1- and C2- will have very high edge rate waveforms. The large dv/dt on these pins can couple energy capacitively to adjacent printed circuit board runs. Magnetic fields can also be generated if the flying capacitors are not close to the LTC3202 (i.e. the loop area is large). To decouple capacitive energy transfer, a Faraday shield may be used. This is a grounded PC trace between the sensitive node and the LTC3202 pins. For a high quality AC ground it should be returned to a solid ground plane that extends all the way to the LTC3202.
VOUT
GND
VIN
VOUT
VIN
Figure 6. Recommended Layouts
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Thermal Management For higher input voltages and maximum output current there can be substantial power dissipation in the LTC3202. If the junction temperature increases above approximately 160C the thermal shutdown circuitry will automatically deactivate the output. To reduce the maximum junction temperature, a good thermal connection to the PC board is recommended. Connecting the GND pin (Pin 5 and Pin 11 on the DFN package) to a ground plane, and maintaining a solid ground plane under the device can reduce the thermal resistance of the package and PC board considerably. Brightness Control Using Pulse Width Modulation An alternative approach to dimming is to use pulse width modulation rather than the internal digital to analog converter. By connecting both the D0 and D1 pins to a PWM signal, continuous brightness control can be achieved. Frequencies from 100Hz to 500Hz are acceptable with a 1F to 4.7F output capacitor.
10 VD0, D1 t D1 D0
3202 F07
D0 LTC3202 D1
1
Figure 7. Alternative Brightness Control
GND
3202 F06
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LTC3202
PACKAGE DESCRIPTIO U
MS Package 10-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1661)
0.889 0.127 (.035 .005) 3.00 0.102 (.118 .004) (NOTE 3) 10 9 8 7 6 5.23 (.206) MIN 3.20 - 3.45 (.126 - .136) 0.254 (.010) 0.50 0.305 0.038 (.0197) (.0120 .0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT GAUGE PLANE 12345 0.53 0.152 (.021 .006) DETAIL "A" 0.18 (.007) NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX SEATING PLANE 0.17 - 0.27 (.007 - .011) TYP 0.127 0.076 (.005 .003)
MSOP (MS) 0603
0.497 0.076 (.0196 .003) REF
DETAIL "A" 0 - 6 TYP
4.90 0.152 (.193 .006)
3.00 0.102 (.118 .004) (NOTE 4)
1.10 (.043) MAX
0.86 (.034) REF
0.50 (.0197) BSC
DD Package 10-Lead Plastic DFN (3mm x 3mm)
(Reference LTC DWG # 05-08-1699)
R = 0.115 TYP 6 0.55 0.05 0.38 0.10 10
3.35 0.05 1.65 0.05 2.25 0.05 (2 SIDES) PACKAGE OUTLINE 0.25 0.05 0.50 BSC 2.38 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2) 2. ALL DIMENSIONS ARE IN MILLIMETERS 3. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 4. EXPOSED PAD SHALL BE SOLDER PLATED PIN 1 TOP MARK
3.00 0.10 (4 SIDES)
1.65 0.10 (2 SIDES)
(DD10) DFN 0103
5 0.200 REF 0.75 0.05 2.38 0.10 (2 SIDES)
1
0.25 0.05 0.50 BSC
0.00 - 0.05
BOTTOM VIEW--EXPOSED PAD
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LTC3202
TYPICAL APPLICATIO
C1 OFF ON 10 1 VIN 3V TO 4.5V C1 1F 4 D0 D1
VIN GND 5, 11
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PART NUMBER LT1618 LT1932 LT1937 LTC3200 LTC3200-5 LTC3201 LTC3250-1.5 DESCRIPTION Constant Current, Constant Voltage 1.4MHz, High Efficiency Boost Regulator Constant Current, 1.2MHz, High Efficiency White LED Boost Regulator Constant Current, 1.2MHz, High Efficiency White LED Boost Regulator Low Noise, 2MHz, Regulator Charge Pump White LED Driver Low Noise, 2MHz, Regulator Charge Pump White LED Driver COMMENTS Up to 16 White LEDs, VIN: 1.6V to 18V, VOUT(MAX): 34V, IQ: 1.8mA, ISD: <1A, 10-Lead MS Up to 8 White LEDs, VIN: 1V to 10V, VOUT(MAX): 34V, IQ: 1.2mA, ISD: <1A, ThinSOTTM Up to 4 White LEDs, VIN: 2.5V to 10V, VOUT(MAX): 34V, IQ: 1.9mA, ISD: <1A, ThinSOT, SC70 Up to 6 White LEDs, VIN: 2.7V to 4.5V, IQ: 8mA, ISD: <1A, 10-Lead MS Up to 6 White LEDs, VIN: 2.7V to 4.5V, IQ: 8mA, ISD: <1A, ThinSOT
Low Noise, 1.7MHz, Regulator Charge Pump White LED Driver Up to 6 White LEDs, VIN: 2.7V to 4.5V, IQ: 6.5mA, ISD: <1A, 10-Lead MS 250mA, 1.5MHz, High Efficiency Step-Down Charge Pump Up to 88% Efficiency, VIN: 3.1V to 5.5V, VOUT: 1.5V, IQ: 35A, ISD: <1A, ThinSOT Up to 88% Efficiency, VIN: 2.7V to 5.5V, VOUT: 0.9V to 1.6V/1.5V, IQ: 8A, ISD: <1A, 10-Lead MS Up to 88% Efficiency, VIN: 2.7V to 5.5V, VOUT: 0.9V to 1.6V, IQ: 60A, ISD: <1A, DFN12 Up to 6 White LEDs, VIN: 2.7V to 16V, VOUT(MAX): 30V, IQ: 2mA, ISD: <1A, ThinSOT
LTC3251/LTC3251-1.5 500mA, Spread Spectrum, High Efficiency Step-Down Charge Pump LTC3252 LT3465/LT3465A Dual, 250mA/Channel, Spread Spectrum, High Efficiency Step-Down Charge Pump Constant Current, 1.2MHz/2.7MHz, High Efficiency White LED Boost Regulator with Integrated Schottky Diode
ThinSOT is a trademark of Linear Technology Corporation.
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507
q
U
LED Driver with Linear Brightness Control
C2 1F C3 1F VC = 0V TO 3V 8
+
7 C1
-
9 C2
+
6 C2
-
3
R2 3.9k
ILED =
(1 + R1 ) 0.6V - R2 36
VC R1 * R2 36
VOUT LTC3202 FB 2 C4 1F R1 1k
36
36
36
36
36
36
3202 TA02
3202fa LT/TP 0803 1K * PRINTED IN USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2001

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