LTC3101 Linear Technology, LTC3101 Datasheet
LTC3101
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LTC3101 Summary of contents
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... The LTC3101 is available in a low profi le (0.75mm) 24-lead 4mm × 4mm QFN package. L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. ...
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... LEAD FREE FINISH TAPE AND REEL LTC3101EUF#PBF LTC3101EUF#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. Consult LTC Marketing for information on non-standard lead based fi nish parts. ...
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... Percentage of Period SW3B is Low in Boost Mode Percentage of Period SW3A is High in Buck Mode PWRON PWRKEY Switch B (From SW3A to GND) Switch C (From SW3B to GND) Switch A´ (From BAT2 to SW3A) Switch A (From USB2 to SW3A) Switch D (From OUT3 to SW3B) LTC3101 = 3V and V = 3.3V, unless BAT2 OUT3 MIN TYP MAX 0.3 ...
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... RESET V Rising CRS Note 4: The LTC3101 is tested in a proprietary non-switching test mode that internally connects the error amplifi ers in a closed-loop confi guration. Note 5: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when overtemperature protection is active. ...
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... BUCK-BOOST ENABLED 50 40 BUCK-BOOST ENABLED BOTH BUCKS DISABLED 5.5 SUPPLY VOLTAGE (V) BAT 3101 G07 LTC3101 (T = 25°C unless otherwise specifi ed) A Buck Effi ciency USB (5V) to 1.8V 100 L = 4.7μH 90 Burst Mode 80 OPERATION 70 60 PWM Mode 4.7μ ...
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... LTC3101 TYPICAL PERFORMANCE CHARACTERISTICS Current Limit Thresholds vs Temperature 10 8 BUCK P-CHANNEL 6 CURRENT LIMIT 4 2 BUCK-BOOST 0 INDUCTOR CURRENT LIMIT –2 –4 –6 –8 –10 – 100 TEMPERATURE (°C) Buck-Boost N-Channel Switch R DS(ON) 250 200 SWITCH B 150 SWITCH C 100 50 www.DataSheet4U.com 0 – 100 TEMPERATURE (° ...
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... LDO Output Voltage vs Supply Voltage 0.5 0.4 0.3 0.2 0.1 0 –0.1 –0.2 –0.3 –0.4 –1 (V) SUPPLY VOLTAGE BAT 3101 G25 LTC3101 (T = 25°C unless otherwise specifi ed) A Buck Output Voltage vs Load Current 0.20 0.15 0.10 0. –0.05 –0.10 –0.15 –0.20 0 100 200 5 6 (V) LOAD CURRENT (mA) ...
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... LTC3101 TYPICAL PERFORMANCE CHARACTERISTICS PBSTAT Deglitch Duration – 100 TEMPERATURE (°C) Buck-Boost Load Step, 0mA to 300mA OUTPUT VOLTAGE 200mV/DIV INDUCTOR CURRENT 500mA/DIV V = 1.8V 50μs/DIV BAT V = 3.3V OUT L = 4.7μ 10μF OUT www.DataSheet4U.com Buck-Boost Burst Mode Ripple ...
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... BAT V = 1.8V OUT I = 100mA LOAD OUTPUT VOLTAGE 500mV/DIV INDUCTOR CURRENT 200mA/DIV 3101 G39 200μs/DIV LTC3101 (T = 25°C unless otherwise specifi ed) A Buck-Boost Output Voltage Transient on USB Hot Plug V USB 2V/DIV INDUCTOR CURRENT 200mA/DIV OUTPUT VOLTAGE 200mV/DIV 3101 G37 ...
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... PWRKEY (Pin 8): Pushbutton Power ON/OFF Key. Forcing this pin to ground will turn on the LTC3101 DC/DC con- verters in the internally controlled sequence and initiate a microprocessor reset. This pin is usually connected to an external momentary switch that is used to turn on the IC. ...
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... IC is enabled (via the pushbutton interface). Forcing this pin below 0.3V will disable buck converter 2. Exposed Pad (Pin 25): Small-Signal and Power Ground for the IC. The Exposed Pad must be soldered to the PCB and electrically connected to ground through the shortest and lowest impedance connection possible. LTC3101 3101f 11 ...
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... LTC3101 BLOCK DIAGRAM MAX CONTROL AND CURRENT LIMIT MAX 11 ALWAYS-ON LDO CONTROL LDO 10 BAT1* 3 USB1* 4 WELL CONTROL SW1 2 BUCK 1 CONTROL FB1 23 ENA1 21 4M WELL CONTROL SW2 www.DataSheet4U.com 5 4M ENA2 24 FB2 22 *BAT1 AND BAT2 MUST BE CONNECTED TOGETHER IN THE APPLICATION USB1 AND USB2 MUST BE CONNECTED TOGETHER IN THE APPLICATION ...
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... SDRAM and a 1.2V rail to supply the system microprocessor. The LTC3101 can operate from any power source over the wide input voltage range of 1.8V to 5.5V. All three switching DC/DC converters operate from a common 1.27MHz oscil- ...
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... C (typical). Once RESET goes high, the microprocessor in the application initializes and must drive the PWRON input of the LTC3101 high in order to keep the LTC3101 enabled. If PWRON is not driven high by the time PWRKEY returns high (i.e., the pushbutton is released) then the LTC3101 will be disabled and all outputs will be actively discharged to ground ...
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... PWRON pin, thereby disabling the LTC3101. Consequently, the LTC3101 will not automatically re-enable even if the fault condition clears. Instead, the LTC3101 will have to be restarted via repeating the normal power-up sequence. Alternatively, if PWRON is held high until the fault condition clears, then any enabled ...
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... BUCK CONVERTER OPERATION The LTC3101 contains two independent buck DC/DC converters each capable of supplying a 350mA load. Each has an adjustable output voltage that can be set as low as 0.6V. In addition, each buck converter supports low drop- out operation to extend battery life ...
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... Current mode control requires the use of slope compensa- tion to prevent sub-harmonic oscillations in the inductor current waveform at high duty cycle operation. This function is performed internally on the LTC3101 through the addition of a compensating ramp to the current sense signal. In some current mode ICs, current limiting is performed by clamping the error amplifi ...
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... PWM Mode Operation When the PWM pin is held high, the LTC3101 buck-boost converter operates in a fi xed frequency pulse width modu- lation mode using voltage mode control. A proprietary switching algorithm allows the converter to transition between buck, buck-boost, and boost modes without discontinuity in inductor current or loop characteristics ...
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... In addition, the output voltage rise time has minimal dependency on the size of the output capaci- tor or load. During soft-start, the buck-boost converter is forced into PWM mode operation regardless of the state of the PWM pin. LTC3101 3101f 19 ...
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... In addition, the MAX and LDO outputs are disabled. The LDO is forced into its reverse blocking state, allowing the LDO output to remain powered with less than 1μA reverse current being drawn by the LTC3101. The soft-start circuits for all DC/DC converters are reset during undervoltage lockout to provide a smooth restart once the input voltage rises above the undervoltage lockout threshold ...
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... APPLICATIONS INFORMATION The basic LTC3101 application circuit is shown as the Typical Application on the front page of this data sheet. The external component selection is dependent upon the required performance of the IC in each particular appli- cation given considerations and tradeoffs such as PCB area, output voltages, output currents, ripple voltages and effi ...
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... A large variety of low ESR, high current power inductors are available that are well suited to LTC3101 buck converter applications. The tradeoff generally involves PCB area, application height, required output current and effi ciency. Table 2 provides a representative sampling of small sur- face mount inductors that are well suited for use with the LTC3101 buck converters. All inductor specifi ...
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... Table 4. Buck Resistor Divider and Feedforward Capacitor Values V OUT 0.6V 0.8V 1. 1.2V 1.5V 1.8V 2.0V 2.7V 3.3V LTC3101 , can be added π 2 • • • – 0 – ...
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... The buck-boost output voltage is set via an external resistor divider connected to the FB3 pin as shown in Figure 5. 5.25 ≥ V OUT3 FB3 LTC3101 GND 3101 F05 Figure 5. Setting the Buck-Boost Output Voltage The resistor divider values determine the buck-boost output voltage according to the following formula: ⎛ ...
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... USB2 and BAT2 pins. In addition, these pins provide 3.0 × 2.8 × 1.5 1.3 4.2 × 4.2 × 1.8 1.50 power to the internal circuitry of the LTC3101 recom- 4.7 × 4.9 × 1.4 1.9 mended that a low ESR ceramic capacitor with a value of at least 10μF be located as close to each of these pins as 4.8 × 4.8 × 1.8 1.65 5.9 × ...
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... BAT1 and BAT2 should be placed as close to the IC as possible and should have the shortest possible paths to ground. 2. The Exposed Pad is the small-signal and power ground connection for the LTC3101. Multiple vias should con- SIZE (mm) L × W × H (FOOTPRINT) nect the backpad directly to the ground plane. In ad- dition maximization of the metallization connected to 1.6 × ...
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... APPLICATIONS INFORMATION ENA3 (19) SW3B (20) ENA1 (21) FB2 (22) FB1 (23) ENA2 (24) www.DataSheet4U.com RS C (12) MAX (11) LDO (10) PBSTAT (9) PWRKEY (8) FB3 (7) LTC3101 3101f 27 ...
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... BAT1 BAT2 SW3A SW3B OUT3 USB1 FB3 C5 USB2 HSO 10μF MAX ENA3 0.22μF ENA2 ENA1 C RS LDO LTC3101 ON/OFF SW2 PWRKEY FB2 R1 R2 50k 50k SW1 PBSTAT PWRON RESET FB1 PWM GND Buck-Boost Converter Effi ciency vs Load Current 100 ...
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... R4 110k 4.7μH SW1 R5 221k FB1 R6 GND 147k ENABLE 5V/DIV 2V/DIV RESET 5V/DIV V 2V/DIV OUT1 V 5V/DIV OUT2 V 5V/DIV OUT3 3101 TA03b LTC3101 V = 3.3V OUT3 300mA FOR V ≥ 1.8V IN 800mA FOR V ≥ 221k Hot Swap OUTPUT 3.3V C5 100mA 4.7μF TRACKING OUTPUT 200mA C6 4.7μF 1.8V 50mA C7 4.7μ ...
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... 10μF 10μF 4.7μH BAT1 BAT2 SW3A SW3B OUT3 USB1 FB3 C2 USB2 HSO 10μF MAX C1 ENA3 0.22μF ENA2 ENA1 C RS LDO LTC3101 L2 ON/OFF 4.7μH SW2 PWRKEY R5 221k FB2 R2 L1 50k 4.7μH PBSTAT SW1 PWRON R7 RESET 221k PWM FB1 GND R8 649k Buck Converter 1 Effi ...
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... TA05a UF Package 24-Lead Plastic QFN (4mm × 4mm) (Reference LTC DWG # 05-08-1697) 4.00 0.10 (4 SIDES) 0.70 0.05 PIN 1 TOP MARK (NOTE 6) PACKAGE OUTLINE 0.25 0.05 0.50 BSC LTC3101 Power-Up Waveforms PWRKEY 5V/DIV PBSTAT 2V/DIV OUTPUT V VOLTAGES OUT3 1V/DIV C 2V/DIV RS RESET 2V/DIV 10ms/DIV BOTTOM VIEW—EXPOSED PAD ...
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... LTC3101 RELATED PARTS PART NUMBER DESCRIPTION LT3009 3μ 20mA Low Dropout Linear Regulator Q LTC3100 700mA Synchronous Step-Up, 250mA Step-Down DC/DC Converters, 100mA LDO LTC3409 600mA, Low V , 2.6MHz Synchronous Step-Down DC/DC IN Converter LTC3440 600mA (I ), 2MHz Synchronous Buck-Boost DC/DC OUT Converter LTC3441 1. 1MHz Synchronous Buck-Boost DC/DC Converter V ...