MPQ4491M The Future of Analog IC Technology Smart, Single USB Charging Port Power Converter with Selectable Frequency for Automotive, AEC-Q100 Qualified DESCRIPTION FEATURES The MPQ4491M integrates a monolithic, stepdown, switch-mode converter and a single USB current-limit switch with charging port identification circuits. It achieves 2.5A of continuous output current with excellent load and line regulation over a wide input supply range. The output of the USB switch is current limited. The MPQ4491M has a USB dedicate charging port (DCP) which supports battery charging specification 1.2 (BC1.2), divider mode, and 1.2V/1.2V mode without the need of outside user interaction. The output voltage has programmable line drop compensation. Full protection features include hiccup current limiting, output over-voltage protection (OVP), and thermal shutdown. The MPQ4491M requires a minimal number of readily available, standard, external components and is available in QFN-26 (4mmx4mm) and QFN-25 (4mmx4mm) packages. EMI Reduction Technique 14V Typical Operating Input Voltage 36V Max. Operating Input Voltage Fixed 5V Output Voltage with Line Drop Compensation Accurate USB Output Current Limit 40mΩ/32mΩ Low-RDS(ON) Internal Buck Power MOSFETs 24mΩ Low-RDS(ON) Internal USB Power MOSFETs 350kHz/250kHz/150kHz Frequency Selectable Programmable Line Drop Compensation Output Over-Voltage Protection (OVP) Hiccup Current Limit Supports DCP Schemes for BC1.2, Divider Mode, and 1.2V/1.2V Mode ±8kV HBM ESD Rating for USB, DP, and DM Available in QFN-26 (4mmx4mm) and QFN25 (4mmx4mm) Packages Available in AEC-Q100 Grade 1 APPLICATIONS USB Dedicated Charging Ports (DCP) Automotive Cigarette Lighter Adapters Power Supply for Linear Chargers All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For MPS green status, please visit the MPS website under Quality Assurance. “MPS” and “The Future of Analog IC Technology” are registered trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 1 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED ORDERING INFORMATION Part Number* MPQ4491MGR MPQ4491MGR-AEC1 MPQ4491MGRE MPQ4491MGRE-AEC1 Package Top Marking QFN-26 (4mmx4mm)** See Below QFN-25 (4mmx4mm) See Below * For Tape & Reel, add suffix –Z (e.g. MPQ4491MGR–Z) **QFN-26 (4mmx4mm) is not recommended for new designs TOP MARKING (QFN-26 (4mmx4mm)) MPS: MPS prefix Y: Year code WW: Week code M4491M: Product code of MPQ4491MGR and MPQ4491MGR-AEC1 LLLLLL: Lot number TOP MARKING (QFN-25 (4mmx4mm)) MPS: MPS prefix Y: Year code WW: Week code M4491M: Product code of MPQ4491MGRE and MPQ4491MGRE-AEC1 LLLLLL: Lot number E: Part of the suffix MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 2 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED PACKAGE REFERENCE NC 22 21 AGND NC 23 VCC DP 24 TOP VIEW VDROP DM TOP VIEW 20 19 18 USB 1 17 NC USB 2 16 NC OUT 3 IN 4 PGND 5 15 OUT 25 OUT 14 IN 26 SW 6 7 8 9 10 11 12 PGND FREQ EN SW SW BST PGND 13 PGND QFN-26 (4mmx4mm) QFN-25 (4mmx4mm) ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance Supply voltage (VIN) ..................................... 40V VSW ...................................................................... -0.3V (-5V for <10ns) to VIN + 0.3V (43V for <10ns) VBST ................................................... VSW + 6.5V (2) All other pins ........................... -0.3V to +6.5V (3) Continuous power dissipation (TA = +25°C) QFN-26 (4mmx4mm) ................................. 2.8W Junction temperature ................................150C Lead temperature .....................................260C Storage temperature ................ -65C to +150C QFN-25 (4mmx4mm) .............. 44 ....... 9.... C/W QFN-26 (4mmx4mm) .............. 44 ....... 9.... C/W Recommended Operating Conditions (4) Typical operating input voltage .................... 14V Max. operating input voltage ........................ 36V Output current ................................ 2.5A for USB Operating junction temp. (TJ). .. -40°C to +125°C (5) θJA θJC NOTES: 1) Absolute maximum ratings are rated under room temperature unless otherwise noted. Exceeding these ratings may damage the device. 2) For details on EN’s ABS MAX rating, please refer to the EN control section on page 11. 3) The maximum allowable power dissipation is a function of the maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD (MAX) = (TJ (MAX)-TA)/θJA. Exceeding the maximum allowable power dissipation produces an excessive die temperature, causing the regulator to go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 4) The device is not guaranteed to function outside of its operating conditions. 5) Measured on JESD51-7, 4-layer PCB. MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 3 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED ELECTRICAL CHARACTERISTICS (6) VIN = 12V, VEN = 5V, TJ = -40°C to +125°C . Typical value is tested at TJ = +25°C, unless otherwise noted. Parameter Symbol Supply current (shutdown) Supply current (quiescent) EN rising threshold EN hysteresis EN input current OL Rising Falling VEN = 2V, TJ = +25°C VEN = 2V, TJ = -40°C to +125°C VEN = 0V IEN Thermal shutdown(7) Thermal hysteresis VEN VEN (7) VCC regulator VCC load regulation Stepdown Converter VIN under-voltage lockout threshold rising VIN under-voltage lockout threshold hysteresis HS switch-on resistance LS switch-on resistance Output voltage Output over-voltage protection OVP recovery 1 5 2.5 1.52 170 2.5 3 Units μA mA V mV μA C TSTD_HYS 20 VCC VCC LOG ICC = 5mA VIN_UVLO TJ = +25°C 4.75 5.1 1 5.45 2 C V % 5.2 5.7 6.2 V 1 V mΩ mΩ 5 40 32 5.05 5.1 4.95 5.05 5.15 5.65 6 6.4 V 5.4 5.75 6.1 1 V VUVLO_HYS RDSON RDSON HS LS VOUT 7V < VIN < 36V, no load, TJ = +25°C 7V < VIN < 36V, no load, TJ = -40°C to +125°C VOVP_R VOVP F Current limit(7) ILIMIT fSW1 fSW2 fSW3 Minimum on time(7) 1.6 1.43 140 1.8 1.8 0 Max 165 SWLKG Maximum duty cycle 1.33 110 1.1 0.8 Typ TSTD Switch leakage Oscillator frequency Min VEN = 0V, TJ = +25°C VEN = 0V, TJ = -40°C to +125°C No switching IIN IQ Condition DMAX TON_MIN TJ = -40°C to +125°C VEN = 0V, VSW = 36V or 0V, TJ = +25°C VEN = 0V, VSW = 36V or 0V, TJ = -40°C to +125°C Over 0-90% duty cycle FREQ = high, TJ = +25°C FREQ = high, TJ = -40°C to +125°C FREQ = low, TJ = +25°C FREQ = low, TJ = -40°C to +125°C FREQ = float, TJ = +25°C FREQ = float, TJ = -40°C to +125°C FREQ = 350kHz TJ = +25°C 5 4 310 300 220 190 125 110 84 V μA A 350 350 250 250 150 150 88 130 MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 410 420 300 330 180 185 kHz % ns 4 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED ELECTRICAL CHARACTERISTICS (continued) (6) VIN = 12V, VEN = 5V, TJ = -40°C to +125°C . Typical value is tested at TJ = +25°C, unless otherwise noted. Parameter Soft-start time Symbol tSS Condition Output from 10% to 90%, TJ = +25°C Output from 10% to 90%, TJ = -40°C to +125°C Min 1 Typ 1.65 Max 2.3 Units 0.9 1.65 2.4 TJ = +25°C TJ = -40°C to +125°C 3.8 3.75 4 4 4.3 4.33 V 220 270 320 mV ms USB Switch Under-voltage lockout threshold rising Under-voltage lockout threshold hysteresis Switch-on resistance Current limit Line drop compensation FREQ, VDROP high level FREQ, VDROP middle level FREQ, VDROP low level VBUS soft-start time Discharge resistance VUSB_UVR VUSB_UVHYS RDSON SW ILimit VDROP COM1 VDROP COM2 VDROP COM3 Off time of hiccup mode 2.6 300 VLOW RDCHG ON1 THICP_ON2 THICP_OFF VOUT = 5V, from 10% to 90%,TJ = +25°C VOUT = 5V, from 10% to 90%, TJ = -40°C to +125°C TJ = +25°C TJ = -40°C to +125°C VOUT = 5V, VBUS connected to GND VOUT = 5V, VBUS > 2V, OC TJ = +25°C VOUT = 5V, VBUS > 2V, OC TJ = -40°C to +125°C VOUT = 5V, VBUS connected to GND, TJ = +25°C VOUT = 5V, VBUS connected to GND, TJ = -40°C to +125°C mΩ A mV mV mV V 2.5 VMIDDLE TSS 2.9 500 VCC 0.4V VHIGH THICP On time of hiccup mode TJ = +25°C Max load 2.4A, VDROP = float, TJ = +25°C Max load 2.4A, VDROP = high Max load 2.4A, VDROP = GND 24 2.75 400 280 130 V 1 1.6 0.4 2.2 0.9 1.6 2.4 50 50 3(7) 70 75 3.5 5 6.5 3 5 7 6.5 8.5 10.5 V ms Ω ms s 6 8.5 11 125 155 125 160 2.7 2.7 22 22 2.82 2.85 30 34 BC1.2 DCP Mode DP and DM short resistance RDP/DM_Short VDP = 0.8V, IDM = 1mA, TJ = +25°C VDP = 0.8V, IDM = 1mA, TJ = -40°C to +125°C Ω Divider Mode DP/DM output voltage VDP/DM_Divider DP/DM output impedance RDP/DM_Divider VOUT = 5V, TJ = +25°C VOUT = 5V, TJ = -40°C to +125°C TJ = +25°C TJ = -40°C to +125°C 2.54 2.5 16 14 MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. V kΩ 5 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED ELECTRICAL CHARACTERISTICS (continued) (6) VIN = 12V, VEN = 5V, TJ = -40°C to +125°C . Typical value is tested at TJ = +25°C, unless otherwise noted. Parameter 1.2V/1.2V Mode Symbol DP/DM output voltage VDP/DM_1.2V DP/DM output impedance RDP/DM_1.2V Condition Min Typ Max VOUT = 5V, TJ = +25°C VOUT = 5V, TJ = -40°C to +125°C TJ = +25°C TJ = -40°C to +125°C 1.16 1.15 55 50 1.25 1.25 68 68 1.34 1.35 80 93 Units V kΩ NOTES: o 6) All min/max parameters are tested at TJ = 25 C. Limits over temperature are guaranteed by design, characterization, and correlation. 7) Guaranteed by design. MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 6 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED TYPICAL PERFORMANCE CHARACTERISTICS VIN = 12V, VOUT = 5V, L = 22µH, fS = 250kHz, TA = 25°C, unless otherwise noted. LINE DROP COMPENSATION (mV) Line Drop Compensation vs. Load Current 100 450 400 350 95 VDROP=Float 90 300 200 80 VDROP=VCC 100 50 0 0 VIN=12V 85 250 150 Efficiency vs. Load Current 0.5 1 1.5 2 LOAD CURRENT (A) VIN=24V 75 VIN=36V 70 VDROP=GND 2.5 VIN=7V 65 0 0.5 1 1.5 2 LOAD CURRENT (A) 2.5 MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 7 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 12V, VOUT = 5V, L = 22µH, fS = 250kHz, TA = 25°C, unless otherwise noted. MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 8 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED PIN FUNCTIONS QFN-25 QFN-26 (4mmx4mm) (4mmx4mm) Pin # Pin # 1, 23 24 2 1, 2 3, 14, 24 3, 15, 25 4, 13 4, 14 5, 6, 11, 12 5, 6, 12, 13 7 7 8 8 9, 25 9, 10, 26 10 11 15 16, 17 16, 17 18 18 19 19 20 20, 21 21, 22 22 23 Name Description D- data line to USB connector. DM is the input/output used for handshaking with portable devices. USB USB output. Buck output. OUT is the power input for USB. The internal circuit OUT senses the OUT voltage and regulates it at 5V. Supply voltage. IN is the drain of the internal power device and power supply for the entire chip. The MPQ4491M operates with a 7V to 36V IN input voltage. CIN is needed to prevent large voltage spikes at the input. Place CIN as close to the IC as possible. Power ground. PGND is the reference ground of the regulated output PGND voltage and requires extra care during PCB layout. Connect PGND to GND with copper traces and vias. Frequency selection. Float FREQ to set the frequency at 150kHz. FREQ Pull FREQ to ground to set the frequency at 250kHz. Pull FREQ high to set the frequency at 350kHz. On/off control input. A 1MΩ resistor is connected between EN and EN GND in the internal circuit. SW Switch output. Use a wide PCB trace to make the connection. Bootstrap. Requires a 0.1µF capacitor connected between SW and BST BST to form a floating supply across the high-side switch driver. No connection. NC can be connected to OUT for better thermal NC dissipation. AGND Analog ground. Connect AGND to PGND. Internal 5V LDO regulator output. Decouple VCC with a 0.22µF VCC capacitor. Line drop compensation selection. Refer to the EC table for detailed VDROP specifications. NC No connection. NC must be left floating. D+ data line to USB connector. DP is the input/output used for DP handshaking with portable devices. DM MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 9 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED BLOCK DIAGRAM IN EN 1MΩ 12KΩ Current Sense Amplifier VCC Regulator 7.6V VCC Oscillator Σ Reference Bootstrap Regulator FREQ HS Driver Current Limit Comparator Control Logic OUT Rtop SS Rbot VCC SW LS Driver PGND Error Amplifier Line Drop Compensation VDROP BST OVP Comparator PWM Comparator Curent Sense USB Discharge Charge Pump UVLO Current Limit Control Logic Thermal Sense Discharge 2.7V AGND 1.2V DP Auto Detect DM NC Figure 1: Functional Block Diagram MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 10 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED OPERATION BUCK CONVERTER SECTION: The MPQ4491M integrates a monolithic, synchronous, rectified, step-down, switch-mode converter with internal power MOSFETs and a USB current-limit switch with charging port auto-detection. The MPQ4491 offers a very compact solution that achieves 2.5A of continuous output current with excellent load and line regulation over a wide input supply range. The MPQ4491M operates in a fixed-frequency, peak-current-mode control to regulate the output voltage. The internal clock initiates the PWM cycle, which turns on the integrated highside power MOSFET (HS-FET). The HS-FET turns on and remains on until its current reaches the value set by the COMP voltage (VCOMP). If the power switch is off, it remains off until the next clock cycle begins. If the duty cycle reaches 88% (350kHz switching frequency) in one PWM period, the current in the power MOSFET cannot reach the value set by VCOMP, and the power MOSFET is forced off. Error Amplifier (EA) The error amplifier (EA) compares the internal feedback voltage against the internal 1V reference (REF) and outputs a COMP voltage which controls the power MOSFET current. The optimized internal compensation network minimizes the external component count and simplifies the control loop design. Internal VCC Regulator The 5V internal regulator powers most of the internal circuitries after pulling EN high. This regulator takes the VIN input and operates in the full VIN range. When VIN is greater than 5.0V, the output of the regulator is in full regulation. When VIN is lower than 5.0V, the output voltage decreases with VIN. An external 0.22µF ceramic capacitor is required for decoupling. Enable Control (EN) The MPQ4491M has an enable control (EN). Pull EN high to enable the IC; pull EN low to disable the IC. Connect EN to VIN through a resistor for automatic start-up. An internal 1MΩ resistor connected from EN to GND allows EN to float to shut down the IC. EN is clamped internally using a 7.6V series Zener diode (see Figure 2). Connecting the EN input through a pull-up resistor to any voltage on VIN limits the EN input current below 230μA and limits the amplitude of the voltage source below 10V to prevent damage to the Zener diode. For example, if 36V is connected to VIN, then RPULLUP ≥ (36V – 10V) / 230µA = 113kΩ. Figure 2: Zener Diode between EN and GND Under-Voltage Lockout (UVLO) Under-voltage lockout (UVLO) protects the chip from operating with an insufficient supply voltage. The UVLO comparator monitors the input voltage. The UVLO rising threshold is 5.7V, while its falling threshold is 4.7V. Internal Soft Start (SS) The soft start (SS) prevents the converter output voltage from overshooting during startup. When the chip starts up, the internal circuitry generates a SS voltage that ramps up from 0V to 5V. When SS is lower than REF, the error amplifier uses SS as the reference. When SS is higher than REF, the error amplifier uses REF as the reference. The SS time is set to 1.65ms internally. If the output of the MPQ4491M is pre-biased to a certain voltage during start-up, the IC disables the switching of both the high-side and low-side switches until the voltage on the internal SS capacitor exceeds the internal feedback voltage. Buck Over-Current Protection (OCP) The MPQ4491M has a cycle-by-cycle overcurrent limit for when the inductor peak current exceeds the current limit threshold and the FB voltage drops below the under-voltage (UV) threshold, typically 70% below the reference. Once UV is triggered, the MPQ4491M enters hiccup mode to restart the part periodically. This protection mode is especially useful when the output is dead-shorted to ground. The MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 11 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED average short-circuit current is greatly reduced to alleviate thermal issues and protect the regulator. The MPQ4491M exits hiccup mode once the over-current condition is removed. Buck Output Over-Voltage Protection (OVP) The MPQ4491M buck converter has output over-voltage protection (OVP). If the output is higher than 6V, the high-side switch stops turning on, and the low-side switch turns on to discharge the output voltage until the output decreases to 5.75V. The chip then resumes normal operation. If the output over-voltage cannot be discharged to 5.75V, the low-side switch turns off after the inductor current reaches a negative current limit. The low-side switch turns on again when the next clock cycle is triggered. Floating Driver and Bootstrap Charging An external bootstrap capacitor powers the floating power MOSFET driver. This floating driver has its own UVLO protection. The UVLO’s rising threshold is 2.2V with a hysteresis of 150mV. The bootstrap capacitor voltage is regulated internally by VIN through D1, M1, C4, L1, and C2 (see Figure 3). If VBST -VSW exceeds 5V, U1 regulates M1 to maintain a 5V BST voltage across C4. Start-Up and Shutdown If both VIN and EN exceed their respective thresholds, the chip is enabled. The reference block starts first, generating a stable reference voltage and current, and then the internal regulator is enabled. The regulator provides a stable supply for the remaining circuitries. Three events can shut down the chip: EN low, VIN low, and thermal shutdown. During the shutdown procedure, the signaling path is blocked first to avoid any fault triggering. The COMP voltage and the internal supply rail are then pulled down. The floating driver is not subject to this shutdown command. Buck Output Discharge The buck portion involves a discharge function that provides a resistive discharge path for the external output capacitor. The function is active when the part is disabled (input voltage is under UVLO, enable off), and is done in a very limited amount of time. After VCC is discharged below 1V, the buck output discharge resistor is disconnected. D1 VIN M1 BST 5V U1 C4 VOUT SW L1 C2 Figure 3: Internal Bootstrap Charging Circuit MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 12 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED USB CURRENT-LIMIT SWITCH SECTION: MPQ4491M adjusts the OVP threshold based on different USB loading currents. Current-Limit Switch The MPQ4491M integrates a single-channel, USB current-limit switch that provides built-in, soft-start circuitry that controls the rising slew rate of the output voltage to limit inrush current and voltage surges. The MPQ4491M uses intelligent line drop compensation and a dynamic over-voltage protection control scheme to ensure that the voltage at the cable terminal meets the 4.75V5.25V specification. When the load current reaches the current-limit threshold (typically 2.75A), the USB power MOSFET switches into foldback current-limit mode, 70% of the current limit (see Figure 4). If the over-current limit condition lasts longer than 3ms, the chip enters hiccup mode with a 3ms on time and an 8.5s off time. Figure 4: Over-Current Limit During VIN or EN start-up, the CC load current cannot exceed 70% of the current limit to avoid triggering a foldback current limit and causing a start-up failure. Output Line Drop Compensation The MPQ4491M can compensate for an output voltage drop, such as high impedance caused by a long trace, to maintain a fairly constant 5V load-side voltage. The MPQ4491M uses the internal currentsense output voltage of the current-limit switch to compensate for the line drop voltage. Since the trace resistance varies for different cables, the MPQ4491M provides selectable line drop compensation through VDROP. The line drop compensation amplitude increases linearly as the load current increases, and also has an upper limitation. USB Output Over-Voltage Protection (OVP) The USB switch’s output uses a dynamic overvoltage protection (OVP) threshold to protect the device at its cable terminal. The USB Output Discharge The USB portion involves a discharge function that provides a resistive discharge path for the external output capacitor. The function is active when the part is disabled (input voltage is under UVLO, enable off), and is done in a very limited amount of time. Auto-Detection The MPQ4491M integrates the USB dedicated charging port auto-detect function, which recognizes most mainstream portable devices. It supports the following charging schemes: USB battery charging specification BC1.2/ Chinese Telecommunications Industry Standard YD/T 1591-2009 Divider mode 1.2V/1.2V mode The auto-detect function is a state machine that supports all of the DCP charging schemes above. For MPQ4491MGRE and MPQ4491MGREAEC1, after power startup, it will enter default divider mode, output voltage is 5.05V with full line drop compensation. If it enters BC1.2 short mode or 1.2V/1.2V mode, output voltage will change to 5.25V with half line drop compensation. By doing this, the device uses BC1.2 mode or 1.2V/1.2V mode that can charge at its full rated current. For MPQ4491MGR and MPQ4491MGR-AEC1, the output voltage is always 5.05V with full line drop compensation no matter which charging mode it is. Thermal Shutdown Thermal shutdown prevents the chip from operating at exceedingly high temperatures. When the silicon die temperature exceeds 165°C, the entire chip shuts down. When the temperature falls below its lower threshold, typically 145°C, the chip is enabled again. MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 13 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED APPLICATION INFORMATION Selecting the Inductor Use an inductor with a DC current rating at least 25% percent higher than the maximum load current for most applications. Select an inductor with a small DC resistance for optimum efficiency. For most designs, the inductor value can be derived from Equation (1): L1 VOUT (VIN VOUT ) VIN IL fOSC (1) Where ∆IL is the inductor ripple current. I L 2 (2) A 22μH toroidal inductor is recommended to improve EMI. Selecting the Buck Input Capacitor The input current to the step-down converter is discontinuous and therefore requires a capacitor to supply AC current to the step-down converter while maintaining the DC input voltage. For best performance, use low ESR capacitors. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. For CLA applications, a low ESR 100μF electrolytic capacitor and twopiece 10μF ceramic capacitors are recommended for EMI reduction. Since the input capacitor (C1) absorbs the input switching current, it requires an adequate ripple current rating. The RMS current in the input capacitor can be estimated with Equation (3): I C1 ILOAD VOUT VOUT 1 VIN VIN The input capacitor can be electrolytic, tantalum, or ceramic. When using electrolytic capacitors, add two high-quality ceramic capacitors as close to IN as possible. The input voltage ripple caused by capacitance can be estimated with Equation (5): VIN Choose the inductor ripple current to be approximately 30% of the maximum load current. The maximum inductor peak current is calculated with Equation (2): IL(MAX ) ILOAD For simplification, choose an input capacitor with an RMS current rating greater than half of the maximum load current. ILOAD V V OUT 1 OUT fS C1 VIN VIN (5) Selecting Buck Output Capacitor The device requires an output capacitor (C2) to maintain the DC output voltage. Estimate the output voltage ripple with Equation (6): VOUT VOUT VOUT 1 fS L1 VIN (6) 1 RESR 8 f C2 S Where L1 is the inductor value and RESR is the equivalent series resistance (ESR) value of the output capacitor. For electrolytic capacitors, the ESR dominates the impedance at the switching frequency. For simplification, the output ripple can be approximated with Equation (7): ∆VOUT VOUT V 1 OUT fS L1 VIN RESR (7) The characteristics of the output capacitor affect the stability of the regulatory system. Low ESR electrolytic capacitors are recommended for low output ripple and good control loop stability. For CLA applications, a 1µF ceramic capacitor and a 270µF polymer or electrolytic capacitor with ~20mΩ ESR are recommended. (3) The worse case condition occurs at VIN = 2VOUT, shown in Equation (4): IC1 ILOAD 2 (4) MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 14 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED (8) PCB Layout Guidelines Efficient PCB layout is critical for stable operation and thermal dissipation. For best results, refer to Figure 5 and follow the guidelines below. 1. Connect OUT using short, direct, and wide traces. It is highly recommended to add vias under the IC and route the OUT trace on both PCB layers. 2. Use a large copper plane for PGND. Multiple vias should be added for better thermal dissipation. 4. Use a large copper plane for SW and USB. 5. Place the USB output capacitor close to USB. 6. Place two ceramic input decoupling capacitors as close to IN and PGND as possible to improve EMI performance. 7. Place the VCC decoupling capacitor as close to VCC as possible. NOTES: 8) The recommended layout is based on Figure 6: Typical Application Circuit on the next page. 3. Connect AGND to PGND. Top Layer Mid1 Layer USB GND BUCK Vo VIN GND Mid2 Layer Bottom Layer Figure 5: Recommended Layout MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 15 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED TYPICAL APPLICATION CIRCUITS 10 Figure 6: VIN = 7V ‐ 36V, USB = 5V/2.5A NOTE: The typical application circuit is based on the QFN-25 (4mmx4mm). MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 16 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED PACKAGE INFORMATION QFN-26 (4mmx4mm) MPQ4491M Rev. 1.01 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 17 MPQ4491M–SMART, SINGLE USB CHARGING PORT POWER CONVERTER WITH SELECTABLE FREQUENCY FOR AUTOMOTIVE, AEC-Q100 QUALIFIED QFN-25 (4mmx4mm) NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. MPQ4491M Rev.1.0 www.MonolithicPower.com 6/5/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 18