LTC3555 Linear Technology, LTC3555 Datasheet
LTC3555
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LTC3555 Summary of contents
Page 1
... Two of the three general purpose switching regulators can provide up to 400mA and the third can deliver 1A. The entire product can be controlled via I The LTC3555 is available in the 28-pin (4mm × 5mm × 0.75mm) QFN surface mount package. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. ...
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... RST3 UFD PACKAGE 28-LEAD (4mm × 5mm) PLASTIC QFN = 125°C, θ 37°C/W JMAX JA EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB UFD PART MARKING LTC3555EUFD 3555 http://www.linear.com/leadfree/ = 3.3V 1k PROG CLPROG MIN TYP 4.35 ● ● ...
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... BAT Rising Threshold Voltage Relative to V Timer Starts when FLOAT BAT < V TRKL (Note 5mA ⎯ C ⎯ H ⎯ R ⎯ ⎯ C ⎯ H ⎯ R ⎯ and BAT) OUT LTC3555 = 3.3V 1k PROG CLPROG MIN TYP 1.188 100 4.30 3.95 4.00 200 50 3.4 BAT + 0.3 4 ...
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... LTC3555 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T unless otherwise noted. SYMBOL PARAMETER NTC V Cold Temperature Fault Threshold COLD Voltage V Hot Temperature Fault Threshold HOT Voltage V NTC Disable Threshold Voltage DIS I NTC Leakage Current NTC Ideal Diode ...
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... OUT2 I = 0μA, FB2 = 0V OUT2 Pulse Skip/Burst Mode Operation Pulse Skip/Burst Mode Operation (GBNT) Forced Burst Mode Operation (GBNT) LDO Mode (GBNT) Full Scale ( (Note 7) Zero Scale ( (Note 7) LTC3555 = 3.3V 1k 3k, CC PROG CLPROG MIN TYP MAX 0.6 ...
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... Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC3555E is guaranteed to meet performance specifi cations from 0°C to 85°C. Specifi cations over the – 40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls ...
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... CLPROG PROG I = 0mA VOUT 88 5x CHARGING EFFICIENCY 86 1x CHARGING 84 EFFICIENCY 2.7 3.0 3.6 3.3 BATTERY VOLTAGE (V) 3555 G07 LTC3555 Output Voltage vs Output Current (Battery Charger Disabled) 4.50 BAT = 4V 4.25 4.00 BAT = 3.4V 3.75 3.50 3.25 3.9 0 200 600 4.2 400 OUTPUT CURRENT (mA) 3555 G02 Battery Drain Current vs Battery Voltage 0μA ...
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... LTC3555 TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage vs Load Current in Suspend 5.0 4.5 4.0 3.5 3 BUS BAT = 3. CLPROG 2.5 0 0.1 0.2 0.3 0.4 LOAD CURRENT (mA) Battery Charge Current vs Temperature 600 500 400 THERMAL REGULATION 300 200 100 PROG 10x MODE 0 –40 – TEMPERATURE (°C) Oscillator Frequency vs Temperature 2 ...
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... OUT3 1.90 350 V IN3 1.85 (CONSTANT FREQUENCY) 300 1.80 250 1.75 1.70 200 85 –40 – TEMPERATURE (°C) 3555 G25 LTC3555 Battery Drain Current vs Temperature 50 BAT = 3. BUS BUCK REGULATORS OFF 3555 G20 0 –40 –15 10 TEMPERATURE (°C) Switching Regulator Low Power Mode Quiescent Currents ...
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... LTC3555 TYPICAL PERFORMANCE CHARACTERISTICS Switching Regulators 1, 2 Pulse Skip Mode Effi ciency 100 2.5V OUT1 1.2V OUT1 1.8V OUT1 IN1 100 LOAD CURRENT (mA) Switching Regulator 3 Pulse Skip Mode Effi ciency 100 V = 3.8V IN3 2.5V OUT3 70 V OUT3 ...
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... EN1 (Pin 16): Logic Input. This logic input pin indepen- dently enables switching regulator 1. This pin is logically 2 OR-ed with its corresponding bit in the I C serial port. See Table 2. LTC3555 2 C Serial Port. If the is grounded, chip control is automati Serial Port. The ...
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... OUT Controller and Input Voltage of the Battery Charger. The majority of the portable product should be powered from V . The LTC3555 will partition the available power be- OUT tween the external load on V charger. Priority is given to the external load and any extra power is used to charge the battery. An ideal diode from ...
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... SDA 10 SCL 9 2.25MHz PowerPath SWITCHING REGULATOR SUSPEND LDO 500μA – – BATTERY 1.188V CHARGE STATUS 4 I LIM DECODE LOGIC PORT LTC3555 LDO3V3 3.3V LDO 24 V OUT + GATE 22 IDEAL CC/CV – CHARGER – 15mV 0. – 23 BAT 3.6V PROG IN1 ENABLE ...
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... HD, STA START CONDITION OPERATION Introduction The LTC3555 is a highly integrated power management IC which includes a high effi ciency switch mode PowerPath controller, a battery charger, an ideal diode, an always- on LDO and three general purpose step-down switching regulators. The entire chip is controlled by either direct 2 digital control serial port or both ...
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... Figure 1 shows the range of possible voltages function of battery voltage. will always be OUT Ideal Diode from BAT to V The LTC3555 has an internal ideal diode as well as a con- troller for an optional external ideal diode. The ideal diode can drop OUT controller is always on and will respond quickly whenever V drops below BAT ...
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... P-channel MOSFET transistor can be added from BAT to V When an external P-channel MOSFET transistor is present, the GATE pin of the LTC3555 drives its gate for automatic ideal diode control. The source of the external P-channel MOSFET should be connected connected to BAT. Capable of driving a 1nF load, the GATE pin can control an external P-channel MOSFET transistor having an on-resistance of 40mΩ ...
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... OPERATION Battery Charger The LTC3555 includes a constant-current / constant-volt- age battery charger with automatic recharge, automatic termination by safety timer, low voltage trickle charging, bad cell detection and thermistor sensor input for out-of- temperature charge pausing. Battery Preconditioning When a battery charge cycle begins, the battery charger fi ...
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... LED while a microprocessor would be able to decode either the 12.5% or 87.5% duty cycles as a bad battery fault. Note that the LTC3555 is a three terminal PowerPath prod- uct where system load is always prioritized over battery charging. Due to excessive system load, there may not be suffi ...
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... Slave Address The LTC3555 responds to only one 7-bit address which has been factory programmed to 0001001. The eighth CC bit of the address byte (R/W) must be 0 for the LTC3555 2 C serial to recognize the address since write only device. This effectively forces the address to be eight bits long where the least signifi ...
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... Stop, it will respond to any Stop that appears on 0.800V the bus, independent of the number of Repeat-Starts that have occurred Repeat-Start is given and the LTC3555 successfully acknowledges its address and fi rst byte, it will not respond to a Stop until both bytes of the new data have been received and acknowledged ...
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... To suit a variety of applica- tions, selectable mode functions can be used to trade-off noise for effi ciency. Four modes are available to control the operation of the LTC3555’s general purpose switching regulators. At moderate to heavy loads, the Pulse Skip mode provides the least noise switching solution. At lighter loads, either Burst Mode operation, Forced Burst Mode operation or LDO mode may be selected ...
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... LTC3555 OPERATION Step-Down Switching Regulator Operating Modes The LTC3555’s general purpose switching regulators include four possible operating modes to meet the noise/ power needs of a variety of applications. In Pulse Skip mode, an internal latch is set at the start of every cycle which turns on the main P-channel MOSFET switch. During each cycle, a current comparator compares the peak inductor current to the output of an error amplifi ...
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... This new circuitry is designed to transition the switch node over a period of a couple of nanoseconds, signifi cantly reducing radiated EMI and conducted supply noise. Low Supply Operation The LTC3555 incorporates an undervoltage lockout circuit on V which shuts down the general purpose switching OUT ...
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... CDRH6D12 CDRH6D38 current. BUS V and V BUS The style and value of capacitors used with the LTC3555 determine several important parameters such as regulator control-loop stability and input voltage ripple. Because will increase OUT the LTC3555 uses a step-down switching power supply from V high frequency components strongly recommended that a low equivalent series resistance (ESR) multilayer in regulation ...
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... DCR losses, and will not give the best ef- fi ciency. The choice of which style inductor to use often depends more on the price vs size, performance and any radiated EMI requirements than on what the LTC3555 requires to operate. The inductor value also has an effect on Forced Burst and Burst Mode operations ...
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... Alternate NTC Thermistors and Biasing The LTC3555 provides temperature qualifi ed charging if a grounded thermistor and a bias resistor are connected ). Only X5R INX to NTC ...
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... R NTC T 100k – 0.349 • V BUS + + – 0.1V (5a) The trip points for the LTC3555’s temperature qualifi ca- tion are internally programmed at 0.349 • V threshold and 0.765 • V Therefore, the hot trip point is set when: R NTCHOT | + R R NOM NTCHOT and the cold trip point is set when: ...
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... USB voltage. To prevent excessive voltage from damag- ing the LTC3555 during a hot insertion best to have a low voltage coeffi cient capacitor at the V LTC3555. This is achievable by selecting an MLCC capaci- tor that has a higher voltage rating than that required for the application. For example, a 16V, X5R, 10μ ...
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... APPLICATIONS INFORMATION Furthermore, due to its high frequency switching circuitry imperative that the input capacitors, inductors and output capacitors be as close to the LTC3555 as possible and that there be an unbroken ground plane under the LTC3555 and all of its external high frequency compo- nents ...
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... MP1 20 23 PROG BAT + 2 CLPROG 29 GND 3k 21 CHRG L2 4.7μH 17 SW1 1.02M 1 19 LDO3V3 FB1 8 1μ 324k 18 V IN1 L3 LTC3555 4.7μH 6 SW2 1.02M 4 FB2 2 9, 365k 5 V IN2 L4 2μH 12 SW3 715k 16 14 EN1 FB3 7 EN2 806k 13 EN3 27 11 ...
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... Plastic QFN (4mm × 5mm) (Reference LTC DWG # 05-08-1712 Rev B) 0.70 ±0.05 3.65 ± 0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 3.50 REF 4.10 ± 0.05 5.50 ± 0.05 0.75 ± 0.05 4.00 ± 0.10 (2 SIDES) PIN 1 TOP MARK (NOTE 6) LTC3555 PIN 1 NOTCH 2.50 REF R = 0.20 OR 0.35 × 45° CHAMFER 0.115 TYP TYP 27 28 3.50 REF 3.65 ± 0.10 2.65 ± 0.10 0.25 ± 0.05 0.200 REF 0.50 BSC 0.00 – ...
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... FAX: (408) 434-0507 25 17 SW1 V BUS 19 FB1 0.1μF 15 RST3 1 7 LDO3V3 EN2 12 1μF SW3 1k LTC3555 14 FB3 13 EN3 10μF 9, EN1 6 SW2 10k 27 ILIM0 28 4 ILIM1 FB2 COMMENTS Seamless Transition Between Input Power Sources: Li-Ion Battery, USB and 5V Wall Adapter. ...