QUICK START GUIDE FOR DC1140A LTC3567EUF: High Efficiency USB Power Manager Plus 1A Buck-Boost Converter with I2C Control DESCRIPTION Demonstration Circuit 1140A is a high efficiency USB Power/Li-Ion battery manager plus a 1A Buck-Boost regulator. The LTC3567EUF is available in a 24-pin (4mm x 4mm) QFN surface mount package. L, LTC, Burst Mode, Bat-Track are registered trademarks of Linear Technology Corporation. PowerPath and SwitcherCAD are trademarks of Linear Technology Corporation. Other product names may be trademarks of the companies that manufacture the products. PERFORMANCE SUMMARY Specifications are at TA = 25C SYMBOL VBUS LDO3V3 VBAT IBAT VOUT1 PARAMETER Bus Input Voltage Range 3.3V LDO Output Voltage Range Battery Float Voltage Battery Charge Current Regulator 1 Output Voltage CONDITIONS Constant Voltage Mode Constant Current Mode, RPROG = 2.00k IOUT1 1000mA MIN 4.35 3.1 4.15 485 3.15 TYP MAX 5.5 3.4 4.23 515 3.45 UNITS V V V mA V OPERATING PRINCIPLES The LTC3567EUF is a full featured USB Power Manager and Li-Ion battery charger with a 1A Buck-Boost DC/DC regulator. The LTC3567EUF has an I2C interface that allows adjustment of the Buck-Boost output voltage, operating mode, and USB power management control. The Bat-TrackTM battery charger pre-regulator ensures the charger operates at the highest possible efficiency. The LTC3567EUF is composed of 6 functional blocks, all working together: USB Power Manager, Pre-regulator, Battery Charger, Ideal Diode, 1A Buck-Boost DC/DC regulator, and I2C. USB Power Manager The USB Power Manager is used to manage the load that the LTC3567EUF system presents to the USB interface. The load current can be programmed by changing the CLPROG resistor (R2), and by setting the operating mode to 1X, 5X or 10X with the I2C interface. Buck-Boost Regulator Efficiency QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER Pre-Regulator The pre-regulator is a high efficiency buck regulator that produces a voltage at VOUT equal to the battery voltage plus 0.3V. By reducing the voltage across the charger to 0.3V the dissipation in the charger is greatly reduced, as compared with a linear charger. Battery Charger The battery charger operates in constant current mode, until the battery voltage rises to approximately the FLOAT voltage, of 4.2V, and then the charger switches to constant voltage mode. The charge current is programmed by the PROG resistor (R3), and has been set to 500mA, on DC1140A, with a 2.00k resistor. The battery charger implements trickle charging, for initial battery voltages less than 2.85V. It also implements a charge termination timeout of 4 hours, and a bad cell charging timeout of 30 minutes. An NTC input is used to determine if the battery temperature is suitable for charging, too hot or too cold. LTC3567EUF 2 I C Interface The I2C interface is a 100kHz, write only serial interface that allows control of the USB input current limit, battery charger on/off, Buck-Boost regulator (VOUT1) on/off, Buck-Boost regulator operating mode, and Buck-Boost output voltage via an internal 4 bit DAC. VOUT1 EN1 Figure 1. VOUT1 startup The statuses of the charger, as well as any faults, are signaled with the CHRG pin. Ideal Diode The Ideal Diode block is composed of an internal Ideal Diode implemented with an on die MOSFET, as well as a MOSFET gate driver that allows the use of a parallel external MOSFET. When the voltage on VOUT drops more than 15mV below the voltage at BAT, the Ideal Diode becomes active. This will happen when VBUS is not present, or the load on VOUT exceeds the power available from VBUS. 1A Buck-Boost DC/DC regulator The Buck-Boost DC/DC regulator provides a regulated output that can be above and below the input voltage. The battery voltage will vary from VFLOAT (4.2V) to as low as 2.5V. The Buck-Boost regulator can supply a regulated 3.3V output over this entire battery voltage range. The Buck-Boost is implemented with a full H-bridge switch, and proprietary control algorithm. 2 IOUT1 = 100mA Figure 2. SWAB1 switching waveform IOUT1 = 100mA Figure3. SWCD1 switching waveform QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER LTC3567EUF APPLICATIONS INFORMATION The parasitic inductance in some USB cables may cause the VUSB voltage to overshoot at plug in. If this is the case it is recommended that the network of C1, R1 and C2 be added to the board to damp out this overshoot. While, at first glance, it may appear that C1 + C2 exceeds the USB specification for capacitive load on VUSB, in fact this is not the case. For most MLCC capacitors, with X7R/X5R dielectric the capacitance will be below 4.7F, for DC biases of 5V. The battery charger must see low impedance to ground, which is the case when a battery is attached. In the event that a battery emulator is being used, or the impedance to ground is above 0.5, the circuit of C7 and R14-16 is recommended. The Buck-Boost regulator should be compensated with a Type III compensator, as shown on the schematic. The Buck, Buck-Boost and pure Boost regions of operation have different poles/zeroes and PWM gains. In particular, the Buck-Boost and pure Boost regions have a RHP zero, that must be accommodated. It is recommended that the stabilization be verified in all three regions of operation, with minimum and maximum load. The /CHRGEN and EN1 pins are wire OR'ed with the corresponding bits from the I2C channel. Consequently, if they are high the battery charger will be disabled and VOUT1 will be enabled. This is true regardless of the state of the I2C bits. If control of the battery charger and VOUT1 through the I2C bits is desired, please ensure that these pins are held low. 3 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER LTC3567EUF SOFTWARE GUI The DC1140A Demo Circuit can be controlled from a software GUI. Most of the features of the LTC3567EUF are only accessible via the I2C channel. When the QuickEval program is active and a DC590 with a DC1140A connected and attached to the USB cable, the "LTC3567" form should automatically pop up and be fully operational: Battery charger button If enabled (default) the battery charger in the LTC3567 will be enabled, and vice versa. VOUT1 buttons Enable or disable VOUT1. This button is only functional if the EN1 pin is held low. Buck-Boost Regulator mode Sets the mode of operation of the Buck-Boost regulator. Buck-Boost Regulator slider Allow control of Buck-Boost regulator output voltage by adjusting the reference DAC. Buck-Boost Regulator output and reference voltage These are not writeable, but reflect the current state of the reference DAC, and feedback resistors. SOFTWARE OPERATION The software GUI automatically opens the control panel shown above. This control panel allows control of most major functions of the LTC3567. Please note that the EN1, and /CHRGEN signals are wire OR'ed with the corresponding bits from the I2C channel. Consequent to this, if either is high, the corresponding bits of the I2C channel will appear to be inoperative. Register A and Register B display These are not writeable and are provided as a programming aid. The current value of the I2C A and B registers are displayed. Update button Forces an immediate update of the I2C registers. Autoupdate button If enabled (default), the I2C channel will update whenever something is changed. 4 Change feedback divider resistor values button This opens the form: This form allows the feedback resistor divider network on the Buck-Boost regulator to be changed. The information changed here, is saved, and is durable from session to session. However, the factory values can be recovered by pressing the "Restore defaults" button. Note that operation of the Buck-Boost regulator below 2.75V must be explicitly enabled. QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER LTC3567EUF QUICK START PROCEDURE Complete the Quick Start Procedure outlined in the Quick Start Guide for Demo Circuit 590 available from the Linear Technology Web Site, prior to proceeding. Using short twisted pair leads for any power connections, with all loads and power supplies off. Refer to Figures 4 & 5 for the proper measurement and equipment setup. Follow the procedure below: NOTE. When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the VBUS or VOUT(x) and GND terminals. See Figure 2 for proper scope probe technique. 1. Set EN1 (JP1) to "OFF" and /CHRGEN (JP4) to "Lo". Set PS1 to 5V, and PS2 to 3.6V. Start the GUI using QuickEval. 2. Observe that 95mA < I (VBUS) (AM1) < 100mA, 3.6V < VOUT(VM2) < 3.7V, 1.15V < V(CLPROG) (VM6) < 1.2V. The default state of the USB input current limit is 100mA, so although the charger is calling for 500mA, the USB input current is limited to 100mA. Consequent to this, VOUT drops until the charger only draws 100mA. 3. Use the GUI to set the USB input current limit to 5X (500mA). Observer that 460mA < I(VBUS) (AM1) < 500mA, 3.8V < VOUT (VM2) < 4.0V, and 0.95V < V(PROG) (VM5) < 1.0V. The USB current limit is now 500mA, so the charger can now deliver the full charge current. VOUT is now approximately equal to V(BAT) + 0.3V, and V(PROG) is a the servo voltage of 1.0V. 4. Use the GUI to set the USB input current limit to 10X (1A). Observe that 460mA < I(VBUS) (AM1) < 500mA, 3.8V < VOUT (VM2) < 4.0V, and 0.95V 5 < V(PROG) (VM5) < 1.0V. The USB current limit is now 1A, so there is more than enough current to operate the charger at 500mA. 5. Set PS1 to 0V, and Ld1 to 1A. Observe that 3.5V < VOUT (VM2) <3.6V and V (VOUT, VBAT) < 200mV. The USB supply is off, and the only source of energy is the battery. With VOUT loaded at 1A, the ideal diode engages and energy is routed from the battery to VOUT. 6. Set Ld1 to 400mA and PS1 to 5V. Observe that 3.8V < VOUT (VM2) < 4.0V. The USB current limit is set to 1A, so both the charger load of 500mA, and 400mA into Ld1 can be supplied. 7. Set Ld1 to 0A, and use the GUI to enable VOUT1. Observe that 3.8V < VOUT (VM2) < 4.0V and 3.25V < VOUT1 (VM4) < 3.35V. The Buck-Boost regulator is now on, at no load. The Buck-Boost regulator operates from VOUT. 8. Set Ld2 to 400mA. Observe 3.8V < VOUT (VM2) < 4.0V, 3.25V < VOUT1 (VM4) < 3.35V. The combined load of the charger and the load on VOUT1, is still within the 1A current limit. 9. Use the GUI to turn off the battery charger, and set Ld2 to 1A. Observe that 3.8V < VOUT (VM2) < 4.0V, 3.25V < VOUT1 (VM4) < 4.0V. Because the battery charger is off, the LTC3567 can supply 1A through the Buck-Boost regulator, and stay within the 1A limit on USB current. 10. Set Ld2 to 0A, and use the GUI to turn on the battery charger. Set NTC (JP3) to "EXT". /CHRG LED should flash. 11. Set NTC (JP3) to "INT" and EN1 (JP1) to "ON". Shut off all supplies and loads. QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER LTC3567EUF AM2 - + - + VM2 - + Ld1 0V-5V 2A - + AM1 - + VM3 + PS1 + 0V-6V supply 2A - AM3 + 3.6 - VM1 + - PS2 0V-5V supply 2A - VM4 VM6 - + + + + AM4 - - - Ld2 0V-5V 2A VM5 + - Linear Technology 14 pin ribbon DC590B USB to I2C concable verter USB cable PC running LTC3567 demonstration software Note: All connections from equipment should be Kelvin connected directly to the board pins which they are connected on this diagram and any input or output leads should be twisted pair. Figure 4. Proper Measurement Equipment Setup for DC1140A GND VIN Figure 5. Measuring Input or Output Ripple 6 E3 E2 Figure 6. Circuit Schematic E5 E4 E7 E6 E8 GND NTC PROG CLPROG CHRGEN EN1 GND USBMINI-B 1 3 5 7 9 11 13 D+ ID D- J2 2 ++ 4 ++ 6 ++ 8 + + 10 + + 12 + + 14 ++ HD2X7 JP1 EN1 R6 5.1K LO R5 2K R11 100K R7 5.1K 5% VOUT Vcc 5 SCLK SDA U2 8 C4 0.1 16V R3 1k R2 1k 1 256X8 2 A0 3 A1 A2 7 WP Vss 24LC025I/ST 4 6 C5 0.1 16V HI ON R4 3.01k CHRGEN JP2 OFF R1 1.0 5% C1 10uF 16V 0805 R12 0 R9 5.1K 5% R8 0 C6 0.1uF 16V C3 22uF 6.3V 0805 20% INT JP3 NTC EXT R10 100K VBUS C2 10uF 16V 0805 3 8 14 13 15 2 23 24 9 R13 0 NTC DVCC SDA SCL GND 25 GND 6 PROG CLPROG CHRGEN EN1 VIN1 LTC3567EUF U1 12 GND BAT VC1 FB1 SWAB1 SWCD1 VOUT1 GATE CHRG VOUT SW LDO3V3 19 5 4 7 11 10 18 16 20 22 1 LPS4018-332MLC L2 3.3uH C8 330pF 5% C9 10pF +/-0.5pF 15k R17 L1 2.2uH LPS4018-222MLC Unless noted: Resistors: Ohms, 0402, 1%, 1/16W Capacitors: uF, 0402, 10%, 50V 17 GND VBUS 21 VBUS C11 22uF 6.3V 0805 20% R18 121k C10 33pF 5% TP5 R19 105k R20 324k R21 20 5% C12 22uF 6.3V 0805 20% R23 0 OPT R14 1.0 5% TP4 INJ 1 2 3 R15 1.0 5% C7 100uF 6.3V 1206 20% R16 1.0 5% R22 1k 5% 0603 D1 GREEN CHGR VOUT Q1 Si2333DS C13 1uF 10V 1 7 2 E1 VBUS 4.35V-5.5V J1 1 VBUS 2 TP1 D3 TP2 USB D+ 4 TP3 ID 5 GND OPT NTC-EXT GND BAT J3 E9 GND E10 BAT VFLOAT=4.2V 500mA E11 GND DF3-3P-2DSA 3 2 1 CHRG E12 VOUT1 3.3V-1.65V 1A E13 E14 GND 3.5V-4.6V 1.25A VOUT GND E15 E16 E17 LDO3V3 3.3V 25mA QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER LTC3567EUF QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER LTC3567EUF Figure 7. Bill of Materials 8