LTC3205 LINER [Linear Technology], LTC3205 Datasheet
LTC3205
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LTC3205 Summary of contents
Page 1
... The part contains a high efficiency, low noise frac- tional step-up/step-down charge pump to provide power for both main and sub white LED displays plus an RGB color LED display. The LTC3205 requires only four small ceramic capacitors plus two resistors to form a complete 3-display LED power supply and current controller. ...
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... MAIN1-MAIN4, SUB1, SUB2 Voltage = MAIN1-MAIN4, SUB1, SUB2 Voltage = 1V MS Any Two MAIN or SUB Outputs 25 A < I < RGB RED, GREEN, BLUE Voltage = TOP VIEW ORDER PART NUMBER LTC3205EUF 18 RED 17 SGND CPO RGB ...
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... LC Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC3205E is guaranteed to meet performance specifications from Specifications over the – operating temperature range are assured by design, characterization and correlation with statistical process controls. ...
Page 4
... LTC3205 W U TYPICAL PERFOR A CE CHARACTERISTICS 1:1 Mode Switch Resistance vs Temperature 1 100mA CPO V = 3. 3.9V IN 0.8 0.7 0.6 –15 35 – TEMPERATURE ( C) 3205 G04 2:3 Mode CPO Voltage in Current Limit 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1 4.2V 0 100 200 300 400 500 600 LOAD CURRENT (mA) 3205 G13 V Shutdown Current ...
Page 5
... C2 D (Pin 7): Input Data for the 16-Bit Serial Port. Serial data IN is shifted in one bit per clock to control the LTC3205 (see Table 1). The logic level for D is referenced SCLK (Pin 8): Clock Input for the 16-Bit Serial Port (see Figure 3) ...
Page 6
... LTC3205 CTIO S V (Pin 16): Supply Voltage for the Charge Pump. The V IN pin should be connected directly to the battery and by- passed with X5R or X7R ceramic capacitor. SGND (Pin 17): Ground for the Control Logic. This pin should be connected directly to a low impedance ground plane ...
Page 7
... To optimize efficiency, the power management section of the LTC3205 provides two methods of supplying power to the CPO pin: 1:1 direct connect mode or 2:3 boost mode. When either the main or sub displays of the LTC3205 are enabled, the power management system connects the CPO pin directly to V with a low impedance switch. If the voltage ...
Page 8
... The LTC3205 can power up to six white LEDs (four for the main display, two for the sub display), however not necessary to have all six in each application. Any of the four main or two sub LED outputs can be disabled by connect- ing the unused output to CPO ...
Page 9
... OPERATIO Unused MAIN or SUB Display LED Pins Any of the six white LED pins (MAIN1-MAIN4, SUB1 and SUB2) can cause the LTC3205 to switch from 1:1 mode to 2:3 charge pump mode if they drop out unused LED pin is left unconnected or grounded, it will automatically drop out and force the LTC3205 into charge pump mode. ...
Page 10
... Likewise, excessive ESR on the output capacitor will tend to degrade the loop stability of the LTC3205. The closed-loop output resis- tance of the LTC3205 is designed to be 0.6 . For a 100mA load current change, the error signal will change by about 60mV. If the output capacitor has 0.6 or more of ESR, ...
Page 11
... 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 LTC3205 (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 LTC3205 pins ...
Page 12
... V equal to 3.6V, the measured efficiency is 92.2%, LED which is very close to the theoretical 92.3% calculation. Once an LED drops out, the LTC3205 switches into step- up mode. Employing the fractional ratio 2:3 charge pump, the LTC3205 provides more efficiency than would be achieved with a voltage doubling charge pump. ...
Page 13
... W U Thermal Management For higher input voltages and maximum output current, there can be substantial power dissipation in the LTC3205. If the junction temperature increases above approximately 160 C 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 ...
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... SUB1 21 SUB2 18 RED 19 GREEN 20 BLUE I I RGB 16.6k 24.9k 14 Ultralow Brightness MAIN and SUB Displays LTC3205 PWM SIGNAL 487k 1.3V OR HIGHER I MS 50Hz TO 15kHz BRIGHTNESS = 1 – RGB 24.9k 24.9k BRIGHT DIM 3205 TA08 SUB DISPLAY CAMERA LIGHT (DUTY CYCLE = 50%) WHITE WHITE ...
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... 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, IF PRESENT 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE LTC3205 CAMERA LIGHT 1 F WHITE WHITE ...
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... LTC3205 U TYPICAL APPLICATIO Li-Ion – ENRGB FROM D LTC3205 IN MICROCONTROLLER 8 SCLK 9 LD SGND STEPUP 17 11 RELATED PARTS PART NUMBER DESCRIPTION ® LT 1618 Constant Current, Constant Voltage, 1.4MHz High Efficiency Boost Regulator LTC1911-1.5 250mA (I ), 1.5MHz High Efficiency ...