MAX20021ATIC/V+T

EVALUATION KIT AVAILABLE MAX20021/MAX20022 General Description The MAX20021/ MAX20022 power-management ICs (PMICs) integrate four low-voltage, high-efficiency, stepdown DC-DC converters. Each of the four outputs is factory or resistor programmable between 1.0V to 4.0V and can deliver up to 1.0A of current. The PMICs operate from 3.0V to 5.5V, making them ideal for automotive pointof-load and post-regulation applications. The PMICs feature fixed-frequency PWM-mode operation with a switching frequency of 2.2MHz or 3.2MHz. Highfrequency operation allows for an all-ceramic capacitor design and small-size external components. The lowresistance on-chip switches ensure high efficiency at heavy loads while minimizing critical inductances, making the layout a much simpler task with respect to discrete solutions. Internal current sensing and loop compensation reduce board space and system cost. The PMICs offer a spread-spectrum option to reduce radiated emissions. Two of the four buck converters operate 180º out-of-phase with the internal clock. This feature reduces the necessary input capacitance and improves EMI as well. All four buck converters operate in constantPWM mode outside the AM band. The PMICs offer a SYNC input to synchronize to an external clock. The PMICs provide individual enable inputs and powergood/reset outputs, as well as factory-programmable RESET times. The PMICs offer several important protection features including: input overvoltage protection, input undervoltage monitoring, input undervoltage lockout, cycle-by-cycle current limiting, and overtemperature shutdown. The input undervoltage monitor indicates a brownout condition by driving PG_ low when the input falls below the UVM threshold. The MAX20021/MAX20022 PMICs are available in a 28-pin TQFN package with an exposed pad and are specified for operation over the -40ºC to +125ºC automotive temperature range. Applications ● Automotive ● Industrial Ordering Information/Selector Guide appear at end of data sheet. For related parts and recommended products to use with this part, refer to www.maximintegrated.com/MAX20021.related. 19-6628; Rev 3; 8/14 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Benefits and Features ● Quad Step-Down DC-DC Converters with Integrated FETs ● Operate from 3.0V to 5.5V Supply Voltage ● 1.0V to 4.0V Fixed or Adjustable Output Voltage ● 2.2MHz (MAX20022) or 3.2MHz (MAX20021) Switching Frequency ● Four Channels Capable of Delivering Up to 1A Each ● Designed to Improve Automotive EMI Performance • Forced-PWM Operation • Two Channels 180º Out-of-Phase • SYNC Input • Spread-Spectrum Option ● Soft-Start and Supply Sequencing Reduces Inrush Current ● Individual Enable Inputs and Power-Good Outputs to Simplify Sequencing ● OV/UV Input-Voltage Monitoring ● Overtemperature and Short-Circuit Protection ● 28-Pin (5mm x 5mm x 0.8mm) TQFN-EP Package ● -40ºC to +125ºC Operating Temperature Range Simplified Block Diagram VOUT1 MAX20021 10kΩ PG_ EN_ CONTROL SEL 5V VA 1µF SS OSC SYNC GND 4 CHANNELS 5V PV_ 2.2µF STEP-DOWN PWM OUT_ 1.0V TO 4.0V UP TO 0.5A OR 1A LX_ EP VOUT_ 10µF PGND_ OUTS_ EN 1.5µH MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Absolute Maximum Ratings PV_ to PGND_......................................................-0.3V to +6.0V VA to GND.............................................................-0.3V to +6.0V OUTS_, EN_, PG_, SYNC, SEL to GND.......-0.3V to VA + 0.3V PV_ to PV_............................................................-0.3V to +0.3V PGND_ to GND.....................................................-0.3V to +0.3V LX_ to PGND...............................................-1.0V to PV_ + 0.3V LX_ Continuous RMS Current...............................................2.0A Output Short-Circuit Duration.....................................Continuous Continuous Power Dissipation (TA = +70ºC) TQFN (derate 28.6mW/ºC above +70ºC)...................2285mW ESDHB..................................................................................±2kV ESDMM...............................................................................±200V Operating Temperature Range...........................-40ºC to +125ºC Junction Temperature....................................................... +150ºC Storage Temperature Range..............................-65ºC to +150ºC Lead Temperature (soldering, 10s).................................. +300ºC Soldering Temperature (reflow)........................................ +260ºC Package Thermal Characteristics (Note 1) TQFN Junction-to-Ambient Thermal Resistance (θJA)...............35°C/W Junction-to-Case Thermal Resistance (θJC)......................3°C/W Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Electrical Characteristics (VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = TJ = -40ºC to +125ºC, unless otherwise noted. Typical values are at TA = +25ºC under normal conditions, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNIT 5.5 V 3.8 5 mA TA = +25°C 0.1 2 TA = +125°C 2 GENERAL Supply Voltage Range VPV_ Fully operational 3.0 Supply Current IPV0 No load, no switching, VEN1 = VEN2 = VEN3 = VEN4 = VPV_ 2.5 Shut-Off Current IVPSD Rising Overvoltage Threshold UVM option enabled www.maximintegrated.com 5.8 VPV_ falling 4.15 VPV_ hysteresis 4.3 Df/f 4.45 0.1 2.68 VPV_ rising fSW 6 0.1 VPV_ falling UVLO Threshold Spread Spectrum 5.6 Hysteresis Undervoltage Monitor Threshold PWM Switching Frequency VEN1 = VEN2 = VEN3 = VEN4 = VGND 3.0 Switching frequency = 2.2MHz (see the Selector Guide) 2.0 2.2 2.4 Switching frequency = 3.2MHz (see the Selector Guide) 3.0 3.2 3.4 Spread-spectrum option = enabled (see the Selector Guide) µA V V V MHz +3 % Maxim Integrated │  2 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Electrical Characteristics (continued) (VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = TJ = -40ºC to +125ºC, unless otherwise noted. Typical values are at TA = +25ºC under normal conditions, unless otherwise noted.) (Note 2) PARAMETER SYNC Input Frequency Range SYMBOL fSYNC CONDITIONS MIN TYP MAX PWM switching frequency = 2.2MHz (see the Selector Guide) 1.7 2.5 PWM switching frequency = 3.2MHz (see the Selector Guide) 2.8 3.5 UNIT MHz OUT1, OUT2, OUT3, OUT4—SYNCHRONOUS STEP-DOWN DC-DC CONVERTERS ILOAD = 0mA Fixed DC Output Accuracy FB DC Set-Point Accuracy +1.5 ILOAD = 0mA to IMAX VSFB_ MAX20022 -3 ILOAD = 0mA ILOAD = 0mA to IMAX +3 1015 970 1030 mV Load Regulation ILOAD = IMAX -1.5 Line Regulation ILOAD = IMAX/2, VPV_ = 4.5V to 5.5V +0.3 pMOS On-Resistance VPV_ = 5.0V, ILX_ = 0.2A 125 250 mΩ nMOS On-Resistance VPV_ = 5.0V, ILX_ = 0.2A 100 200 mΩ 1.65 2 pMOS Current-Limit Threshold ILIM 1.0A channel output (see the Selector Guide) 1.4 0.5A channel output (see the Selector Guide) 0.8 IB_OUTS_ LX Leakage Current % % A Soft-Start Ramp Time OUTS Leakage Current -2.5 % 1.1 1.5 3272 Cycles Externally adjustable output 20 nA VPV_ = 5.0V, LX_ = VPGND_ or VPV_ 0.1 Minimum On-Time 45 LX Rise/Fall Time 4 Duty Cycle Range µA 66 ns ns 100 % OUTS_ Discharge Resistance VEN_ = VGND 35 Ω OUT1, OUT2 Phasing (Note 3) 0 Degrees OUT3, OUT4 Phasing (Note 3) 180 Degrees Thermal-Shutdown Temperature TJ rising (Note 4) +185 ºC Hysteresis (Note 4) 15 ºC THERMAL OVERLOAD OUTPUT POWER-GOOD INDICATORS (PG_) Output Overvoltage Threshold Output Undervoltage Threshold www.maximintegrated.com VOUT rising (percentage of nominal output) 106 110 114 VOUT falling (percentage of nominal output) 92.5 94 96 VOUT rising (percentage of nominal output) 93.5 95 97 % % Maxim Integrated │  3 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Electrical Characteristics (continued) (VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = TJ = -40ºC to +125ºC, unless otherwise noted. Typical values are at TA = +25ºC under normal conditions, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNIT UV/OV Propagation Delay 15 µs PG_ Output High Leakage Current 0.1 µA PG_ Output Low Level VPV_= 3.0V, sinking 3mA 0.22 V 1.3 V ENABLE INPUTS (EN_) Input High Level VPV_ = 5.0V, VEN_ rising Hysteresis VPV_ = 5.0V, VEN_ falling 0.7 Pulldown Resistance 1.0 50 mV 100 kΩ DIGITAL INTERFACE (SYNC, SEL) Input Voltage High VINH Input Voltage Low VINL 1.5 V 0.5 V Input Voltage Hysteresis 70 mV Pulldown Resistance 100 kΩ Note 2: All units are 100% production tested at +25ºC. All temperature limits are guaranteed by design. Note 3: Phase measurement is in relation to the rising edge of VLX_. Note 4: Guaranteed by design. Not production tested. www.maximintegrated.com Maxim Integrated │  4 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Typical Operating Characteristics (VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = +25ºC, unless otherwise noted.) VOUT1 = 3.3V 70 50 80 VOUT3 = 2.65V VOUT4 = 1.8V 40 30 20 VOUT1 = 3.3V 70 60 50 VOUT3 = 2.65V 40 VOUT4 = 1.8V 30 VOUT2 = 1.2V 20 VOUT2 = 1.2V 10 0 0.0001 fSW = 2.2MHz, VPV_ = 5V 0.0100 0.1000 0 0.0001 1.0000 LOAD CURRENT (A) 0.0010 0.0100 0.1000 600 LX_ TO PGND_ 300 200 TA = +25ºC 15 TA = -40ºC 10 0 2.7 3.2 3.7 4.2 4.7 5.2 5.7 LOAD REGULATION (BUCK 1) 3.34 3.32 3.30 3.28 3.26 3.24 100 3.22 0 LX_ TO PV_ -60 -40 -20 0 3.20 20 40 60 80 100 120 140 TEMPERATURE (ºC) 100.8 MAX20021 toc06 LINE REGULATION (BUCK 2) 101.0 VOUT2 (% NOMINAL) 1.0000 3.36 VOUT1 (V) LX LEAKAGE CURRENT (nA) 700 -100 TA = +125ºC 20 SUPPLY VOLTAGE (V) MAX20021 toc04 800 400 VPV_ = VA = VEN_ 25 LOAD CURRENT (A) LX LEAKAGE CURRENT vs. TEMPERATURE 500 30 5 10 0.0010 SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX20021 toc05 60 90 SUPPLY CURRENT (mA) EFFICIENCY (%) 80 100 MAX20021 toc02 fSW = 3.2MHz, VPV_ = 5V EFFICIENCY (%) 90 MAX20021 toc01 100 BUCK EFFICIENCY (2.2MHz) vs. LOAD CURRENT MAX20021 toc03 BUCK EFFICIENCY (3.2MHz) vs. LOAD CURRENT TA = +125ºC 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 IOUT1 (A) STARTUP SEQUENCE MAX20021 toc07 VOUT1 100.6 100.4 VOUT2 TA = +25ºC 100.2 100.0 VOUT3 99.8 99.6 TA = -40ºC 2.7 3.2 3.7 4.2 VPV2 (V) www.maximintegrated.com 4.7 5.2 VOUT4 5.7 2ms/div Maxim Integrated │  5 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Typical Operating Characteristics (continued) (VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = +25ºC, unless otherwise noted.) SHORT-CIRCUIT BEHAVIOR LOAD TRANSIENT, (VOUT1 = 3.3V) MAX20021 toc08 MAX20021 toc09 VOUT3 2V/div IOUT1 500mA/div VLX3 2V/div VOUT1 100mV/div IOUT3 1A/div 400ns/div 10µs/div LINE TRANSIENT, (VOUT1 = 3.3V) SWITCHING FREQUENCY vs. TEMPERATURE MAX20021 toc10 VPV1 = 3.8V VPV1 1V/div VOUT1 50mV/div MAX20021 toc11 VPV1 = 5.2V 102 fSW (% NOMINAL) VPV1 = 3.8V 103 101 100 99 98 DROPOUT VOLTAGE vs. LOAD CURRENT (BUCK 1) VPV1 - VOUT1 (mV) 300 250 200 150 100 50 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 IOUT1 (A) www.maximintegrated.com P-CHANNEL SWITCH RESISTANCE vs. SUPPLY VOLTAGE 0.35 P-CHANNEL SWITCH RESISTANCE (Ω) MAX20021 toc12 350 -60 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (°C) MAX20021 toc13 97 10ms/div TA = +125ºC 0.30 TA = +25ºC 0.25 0.20 0.15 TA = -40ºC 0.10 0.05 0 2.7 3.2 3.7 4.2 4.7 5.2 5.7 VPV_ (V) Maxim Integrated │  6 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Typical Operating Characteristics (continued) (VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = +25ºC, unless otherwise noted.) 0 MAX20021 toc15 MAX20021 toc14 45 PHASE MARGIN vs. FREQUENCY 200 150 PHASE MARGIN (°) MAGNITUDE (dB) 90 SMALL-SIGNAL GAIN vs. FREQUENCY 100 50 0 -50 1E+4 1E+5 PSRR (dB) 1E+4 1E+5 1E+6 PSRR vs. FREQUENCY OUTPUT VOLTAGE-NOISE DENSITY vs. FREQUENCY -30 NO LOAD -50 -60 150mA LOAD -70 0.001 0.010 0.100 1.000 10.000 100.000 1000.000 FREQUENCY (kHz) 10,000 VPV_ = 5V VOUT_ = 1.2V IOUT_ = 0mA 1000 MAX20021 toc17 FREQUENCY (Hz) -20 www.maximintegrated.com 1E+3 FREQUENCY (Hz) -10 -40 -100 1E+2 1E+6 OUTPUT VOLTAGE-NOISE DENSITY (nV/√Hz) 0 1E+3 MAX20021 toc16 -45 1E+2 100 10 1 0 500 1000 1500 2000 2500 3000 3500 4000 RF FREQUENCY (MHz) Maxim Integrated │  7 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters PV4 LX4 PGND4 PGND3 LX3 PV3 TOP VIEW EN4 Pin Configuration 21 20 19 18 17 16 15 OUTS4 22 14 OUTS3 PG4 23 13 EN3 12 PG3 11 SEL 10 PG2 9 EN2 8 OUTS2 GND 24 MAX20021 SYNC 25 VA 26 PG1 27 EP = GND PV1 LX1 4 5 6 7 PV2 3 LX2 2 PGND2 1 EN1 OUTS1 28 PGND1 + TQFN Pin Description PIN NAME 1 EN1 Active-High Digital Enable Input for Buck 1. Driving EN1 high enables Buck 1. 2 PV1 Buck 1 Voltage Input. Connect a 2.2µF or larger ceramic capacitor from PV1 to PGND1 as close as possible to the device. 3 LX1 Buck 1 Switching Node. LX1 is high impedance when the device is off. 4 PGND1 Power Ground for Buck 1 5 PGND2 Power Ground for Buck 2 6 LX2 Buck 2 Switching Node. LX2 is high impedance when the device is off. 7 PV2 Buck 2 Voltage Input. Connect a 2.2µF or larger ceramic capacitor from PV2 to PGND2 as close as possible to the device. 8 OUTS2 9 EN2 Active-High Digital Enable Input for Buck 2. Driving EN2 high enables Buck 2. 10 PG2 Open-Drain, Active-High, Power-Good Output for Buck 2. To obtain a logic signal, pull up PG2 with an external resistor connected to a positive voltage equal to or lower than VA. 11 SEL Buck 3 Output-Voltage Select Input. Connect SEL to PGND_ for a 1.8V output. Connect SEL to PV_ for a 2.65V output. Do not toggle during normal operation. 12 PG3 Open-Drain, Active-High, Power-Good Output for Buck 3. To obtain a logic signal, pull up PG3 with an external resistor connected to a positive voltage equal to or lower than VA. 13 EN3 Active-High Digital Enable Input for Buck 3. Driving EN3 high enables Buck 3. 14 OUTS3 www.maximintegrated.com FUNCTION Buck 2 Voltage Sense Input Buck 3 Voltage Sense Input Maxim Integrated │  8 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Pin Description (continued) PIN NAME FUNCTION PV3 Buck 3 Voltage Input. Connect a 2.2µF or larger ceramic capacitor from PV3 to PGND3 as close as possible to the device. 16 LX3 Buck 3 Switching Node. LX3 is high impedance when the device is off. 17 PGND3 Power Ground for Buck 3 18 PGND4 Power Ground for Buck 4 19 LX4 Buck 4 Switching Node. LX4 is high impedance when the device is off. 20 PV4 Buck 4 Voltage Input. Connect a 2.2µF or larger ceramic capacitor from PV4 to PGND4 as close as possible to the device. 21 EN4 Active-High Digital Enable Input for Buck 4. Driving EN4 high enables Buck 4. 22 OUTS4 23 PG4 Open-Drain, Active-High, Power-Good Output for Buck 4. To obtain a logic signal, pull up PG4 with an external resistor connected to a positive voltage equal to or lower than VA. 24 GND Analog Ground 25 SYNC SYNC Input. Supply an external clock to control the switching frequency. Connect SYNC to PGND_ to use the default switching frequency. 26 VA Analog Voltage Supply. Connect a 1µF or larger ceramic capacitor from VA to GND as close as possible to the device. Connect to the same supply as PV_ inputs. 27 PG1 Open-Drain, Active-High, Power-Good Output for Buck 1. To obtain a logic signal, pull up PG1 with an external resistor connected to a positive voltage equal to or lower than VA. 28 OUTS1 15 — www.maximintegrated.com EP Buck 4 Voltage Sense Input Buck 1 Voltage Sense Input Exposed Pad. Connect the exposed pad to ground. Connecting the exposed pad to ground does not remove the requirement for proper ground connections to PGND1–PGND4 and GND. The exposed pad is attached with epoxy to the substrate of the die, making it an excellent path to remove heat from the IC. Maxim Integrated │  9 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters CURRENT-SENSE AMP PV1—PV4 VREF PEAK CURRENT COMP RAMP GENERATOR PV1 ∑ PWM COMP PGND1 CONTROL LOGIC PV1 VREF PGND1 SOFT-START GENERATOR OUTS1— OUTS4 LX1—LX4 CLK180 CLK PGND1 —PGND4 VALLEY CURRENT LIM COMP P1-OK FEEDBACK SELECT SEL VREF SYNC OSC P-OK[1:4] OTP CLK VOLTAGE REFERENCE MAX20021 EN1 TRIMBITS CLK180 VREF UVLO VA VA PG1 PG2 EN2 EN3 EN4 MAIN CONTROL LOGIC PG3 PG4 SEL GND Figure 1. Internal Block Diagram www.maximintegrated.com Maxim Integrated │  10 MAX20021/MAX20022 Detailed Description The MAX20021/MAX20022 PMICs offer four, highefficiency, synchronous step-down converters that operate with a 3.0V to 5.5V input voltage range and provide a 1.0V to 4.0V output voltage range. The PMICs deliver up to 1.0A of load current per output. The PMICs achieve ±3% output error over load, line, and temperature ranges. The PMICs feature fixed-frequency PWM-mode operation with a 2.2MHz or 3.2MHz switching frequency. An optional spread-spectrum frequency modulation minimizes radiated electromagnetic emissions due to the switching frequency, while a factory-programmable synchronization input (SYNC) allows the device to synchronize to an external clock. Integrated low RDSON switches help minimize efficiency losses at heavy loads and reduce critical/parasitic inductance, making the layout a much simpler task with respect to discrete solutions. The PMICs are offered in factory-preset output voltages to allow customers to achieve ±3% output-voltage accuracy, without using expensive 0.1% resistors. In addition, adjustable output-voltage versions can be set to any desired values between 1.0V and 4.0V using an external resistive divider. See the Selector Guide for available options. Additionally, each converter features soft-start, PG_ output, overcurrent, and overtemperature protections (see Figure 1). Control Scheme The PMICs use peak current-mode control. The devices feature internal slope compensation and internal loop compensation, both of which reduce board space and allow a very compact solution. Hybrid Load-Line Architecture The PMICs feature hybrid load-line architecture to reduce the output capacitance needed, potentially saving system cost and size. This results in a measurable load transient response. Input Overvoltage Monitoring (OV) The PMICs feature an input overvoltage-monitoring circuit on the input supply. When the input exceeds 5.8V (typ) all power-good indicators (PG_) go low. When the input supply returns to within the operating range of 5.7V (typ) or less during the timeout period, the power-good indicators go high. Input Undervoltage Monitoring (UVM) The MAX20021 features an input undervoltage monitoring circuit on the input supply. When the input drops below www.maximintegrated.com Automotive Quad, Low-Voltage Step-Down DC-DC Converters 4.3V (typ), all power-good indicators (PG_) go low to indicate a potential brownout condition. The device remains operational down to the UVLO threshold. When the input voltage exceeds the UV threshold above 4.4V (typ), PG_ remains low for the factory-trimmed “active timeout period.” UVM is a factory-selectable option. Input Undervoltage Lockout (UVLO) The PMICs feature an undervoltage lockout on the PV_ inputs set at 2.77V (typ) falling. This prevents loss of control of the device by shutting down all outputs. This circuit is only active when at least one buck converter is enabled. Power-Good Outputs (PG_) The PMICs feature an open-drain power-good output for each of the four buck regulators. PG_ asserts low when the output voltage drops 6% below the regulated voltage or 10% above the regulated voltage for approximately 15µs. PG_ remains asserted for a fixed 20,480 switching cycles after the output returns to its regulated voltage. PG_ asserts low during soft-start and in shutdown. PG_ becomes high impedance when Buck_ is in regulation. Connect PG_ to a logic supply with a 10kΩ resistor. Soft-Start The PMICs include a 3272 switching cycle fixed-duration soft-start time. The soft-start time limits startup inrush current by forcing the output voltage to ramp up towards its regulation point. During soft-start, the converters operate in skip mode to prevent the outputs from discharging. When the PMICs exit UVLO or thermal shutdown, there is a fixed blanking time for EN2–EN4 to prevent all four outputs from going through soft-start at the same time. After 24,576 switching cycles with UVLO high and at least one buck converter enabled, there is no blanking time between EN2–EN4 high and the start of soft-start. +5.0% +1.5% 0% -1.0% -3.5% 4µs 4µs 1.0A 0A 1µs 1µs Figure 2. Load Transient Response Maxim Integrated │  11 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Output 3 Voltage Select (SEL) The MAX20021 offers a SEL input to allow selection of the OUT3 voltage. For fixed output versions, connect SEL to PGND_ for a 1.8V output or to PV_ for a 2.65V output. There is no soft transition between the two output-voltage settings, so SEL should not be toggled during normal operation. For the MAX20022, connect SEL to PGND_ or leave unconnected. condition at an output, the high-side MOSFET remains on until the inductor current reaches the high-side MOSFET’s current-limit threshold. The converter then turns on the low-side MOSFET and the inductor current ramps down. The converter allows the high-side MOSFET to turn on only when the inductor current ramps down to the lowside MOSFET’s current threshold. This cycle repeats until the short or overload condition is removed. Spread-Spectrum Option Overtemperature Protection The PMICs feature a linear spread-spectrum (SS) operation, which varies the internal operating frequency between fSW and (fSW + 3%). The internal oscillator is frequency modulated at a rate of 1.5kHz with a frequency deviation of 3% (see Figure 4). This function does not apply to an oscillation frequency applied externally through the SYNC pin. Spread spectrum is a factory-selectable option. See the Selector Guide for available options. Synchronization (SYNC) The PMICs feature a SYNC input to allow the internal oscillator to synchronize with an external clock. SYNC accepts signal frequencies in the range of 1.7MHz < fSYNC < 2.5MHz (2.2MHz option), or 2.7MHz < fSYNC < 3.5MHz (3.2MHz option). Connect to PGND_ if the SYNC feature is not used. Current Limit /Short-Circuit Protection The PMICs offer a current-limit feature that protects the devices against short-circuit and overload conditions on each output. In the event of a short-circuit or overload UVLO Thermal-overload protection limits the total power dissipation in the PMICs. When the junction temperature exceeds 185ºC (typ), an internal thermal sensor shuts down the step-down converters, allowing the IC to cool. The thermal sensor turns on the IC again after the junction temperature cools by 15ºC. The IC goes through a standard power-up sequence as defined in the Soft-Start section. Applications Information Adjustable Output-Voltage Option The MAX20022 features adjustable output voltages (see the Selector Guide for more details), which allows the customer to set the outputs to any voltage between 1.0V and VPV_ - 0.5V (up to 4.0V). Connect a resistive divider from output (VOUT_) to OUTS_ to GND to set the output voltage (see Figure 5). Select R2 (OUTS_ to the GND resistor) less than or equal to 100kΩ. Calculate R1 (VOUT_ to the OUTS_ resistor) with the following equation:  VOUT_    − 1 = R1 R2   VOUTS_   where VOUTS_ = 1000mV (see the Electrical Characteristics table). The output voltage is nominal at 50% load current. EN1—EN4 OUT1 OUT2 fSW + 3% OUT3 INTERNAL OSCILLATOR FREQUENCY OUT4 fSW 8192 CYCLES t 16,384 CYCLES t + 667µs t + 1.334ms TIME 24,576 CYCLES 3272 CYCLES 3272 CYCLES Figure 4. Effect of Spread-Spectrum on Internal Oscillator 3272 CYCLES Figure 3. Power-Up Soft-Start Delays www.maximintegrated.com Maxim Integrated │  12 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters The external feedback resistive divider must be frequency compensated for proper operation. Place a capacitor across R1 in the resistive divider network. Use the following equation to determine the value of the capacitor: R2  R2  > 1, C1 = C  R1  R1  else C1 C, where C 15pF = = If Connect OUTS_ to VOUT_ for a fixed 1.0V output voltage. Inductor Selection The PMICs are optimized for use with a 1.5µH inductor for 2.2MHz and 3.2MHz operation. Chip inductors can be used for additional board-space savings. Input Capacitor The PMICs are designed to operate with a single 2.2µF ceramic bypass capacitor on each PV_ input. Phase interleaving of the four buck converters contributes to a lower required input capacitance by canceling input ripple currents. Place the bypass capacitors as close as possible to their corresponding PV_ input to ensure the best EMI and jitter performance. Output Capacitor All outputs of the PMICs are optimized for use with a 10FF X7R ceramic capacitor. Additional output capacitance can be used if better voltage ripple or load transient response is required. Due to the soft-start sequence, the device is unable to drive arbitrarily large output capacitors. Thermal Considerations How much power the package can dissipate strongly depends on the mounting method of the IC to the PCB and the copper area for cooling. Using the JEDEC test standard, the maximum power dissipation allowed is 2285mW in the TQFN package. More power dissipation can be handled by the package if great attention is given during PCB layout. For example, using the top and bottom copper as a heatsink and connecting the thermal vias to one of the middle layers (GND) transfers the heat from the package into the board more efficiently, resulting in lower junction temperature at high power dissipation in some PMIC applications. Furthermore, the solder mask around the IC area on both top and bottom layers can be removed to radiate the heat directly into the air. The maximum allowable power dissipation in the IC is as follows: PMAX = (TJ(MAX) − TA ) θ JC + θ CA where TJ(MAX) is the maximum junction temperature (+150ºC), TA is the ambient air temperature, BJC (3ºC/W for the 28-pin TQFN) is the thermal resistance from the junction to the case, and θCA is the thermal resistance from the case to the surrounding air through the PCB, copper traces, and the package materials. θCA is directly related to system-level variables and can be modified to increase the maximum power dissipation. The TQFN package has an exposed thermal pad on its underside. This pad provides a low thermal-resistance path for heat transfer into the PCB. This low thermally resistive path carries a majority of the heat away from the IC. The PCB is effectively a heatsink for the IC. The exposed pad should be connected to a large ground plane for proper thermal and electrical performance. The minimum size of the ground plane is dependent upon many system variables. To create an efficient path, the exposed pad should be soldered to a thermal landing, which is connected to the ground plane by thermal vias. The thermal landing should be at least as large as the exposed pad and can be made larger depending on the amount of free space from the exposed pad to the other pin landings. A sample layout is available on the MAX20022 evaluation kit to speed designs. PCB Layout Guidelines VOUT_ R1 1) Use a large contiguous copper plane under the PMIC packages. Ensure that all heat-dissipating components have adequate cooling. MAX20022 OUTS_ R2 Figure 5. Adjustable Output-Voltage Configuration www.maximintegrated.com C1 Careful PCB layout is critical to achieve low switching losses and clean, stable operation. Use a multilayer board whenever possible for better noise immunity and power dissipation. Follow these guidelines for good PCB layout: 2) Keep the high-current paths short, especially at the ground terminals. This practice is essential for stable, jitter–free operation. The high current path comprising of input capacitor, inductor, and the output capacitor should be as short as possible. Maxim Integrated │  13 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters 3) Keep the power traces and load connections short. This practice is essential for high efficiency. Use thick copper PCBs (2oz vs. 1oz) to enhance full-load efficiency. 4) Use a single ground plane to reduce the chance of ground potential differences. With a single ground plane, enough isolation between analog return signals and high-power signals must be maintained. Typical Operating Circuit VOUT1 10kΩ VOUT1 EN1 PG1 EN2 PG2 10kΩ EN3 CONTROL PG3 EN4 PG4 SEL 5V VA 1µF 5V MAX20021 SS OSC GND PV2 SYNC 2.2µF 1.5µH 1.25V 2.2µF LX2 10µF PGND2 OUTS2 5V STEP-DOWN PWM OUT2 STEP-DOWN PWM OUT1 1.0V TO 4.0V 500mA 1.0V TO 4.0V 1.0A EN EN PV3 LX1 1.5µH 1.5µH 3.3V 10µF PGND1 OUTS1 5V PV4 2.2µF 2.65V OR 1.8V 5V PV1 2.2µF LX3 10µF PGND3 OUTS3 STEP-DOWN PWM OUT3 STEP-DOWN PWM OUT4 1.0V TO 4.0V 500mA 1.0V TO 4.0V 1.0A EN EN LX4 1.5µH 1.8V 10µF PGND4 OUTS4 EP www.maximintegrated.com Maxim Integrated │  14 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Ordering Information FREQUENCY TEMP RANGE MAX20021ATI_ / V+ PART 3.2MHz -40ºC to +125ºC PIN-PACKAGE 28 TQFN-EP* MAX20022ATI_ / V+ 2.2MHz -40ºC to +125ºC 28 TQFN-EP* Note: Insert the desired suffix letter (from the Selector Guide) into the blank area "_" to indicate factory-selectable features. /V denotes an automotive qualified part that conforms to AEC-Q100. +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. Selector Guide* PART CURRENT CONFIGURATION DC-DC1 DC-DC2 CH1 CH2 CH3 CH4 DC-DC3 DC-DC4 VOUT (V) SPREAD FREQUENCY SPECTRUM (MHz) UVM ACTIVE TIMEOUT PERIOD (CYCLES) MAX20021 MAX20021ATIA/V+ 1.0A 0.5A 0.5A 1.0A 3.30 1.25 2.65/1.80 1.80 Disabled 3.2MHz Enabled 20,480 MAX20021ATIB/V+ 1.0A 0.5A 0.5A 1.0A 3.30 1.25 2.65/1.80 1.80 Enabled 3.2MHz Enabled 20,480 MAX20021ATIC/V+ 1.0A 0.5A 0.5A 1.0A 3.30 1.20 2.65/1.80 1.50 Disabled 3.2MHz Enabled 20,480 MAX20021ATID/V+ 1.0A 0.5A 0.5A 1.0A 3.30 1.20 2.65/1.80 1.80 Disabled 3.2MHz Enabled 20,480 MAX20022 MAX20022ATIA+ 1.0A 1.0A 1.0A 1.0A Adjustable Adjustable Adjustable Adjustable Disabled 2.2MHz Disabled 256 MAX20022ATIA/V+ 1.0A 1.0A 1.0A 1.0A Adjustable Adjustable Adjustable Adjustable Disabled 2.2MHz Disabled 256 MAX20022ATIB+ 1.0A 1.0A 1.0A 1.0A Adjustable Adjustable Adjustable Adjustable Enabled 2.2MHz Disabled 256 MAX20022ATIB/V+ 1.0A 1.0A 1.0A 1.0A Adjustable Adjustable Adjustable Adjustable *Contact factory for options that are not included. Factory-selectable features include: ● DC-DC voltages in 100mV steps between 1.0V and 4.0V. ● Spread spectrum enabled or disabled. ● UVM enabled or disabled. ● Number of cycles in active timeout period ● Independent current limit for each channel up to 1A. Enabled 2.2MHz Disabled 256 Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 28 TQFN-EP T2855+5 21-0140 90-0025 www.maximintegrated.com Maxim Integrated │  15 MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 0 3/13 Initial release — 1 4/13 Removed future product reference for the MAX20022 15 2 12/13 Added AEC-Q100 reference to Ordering Information 15 3 8/14 Added two new MAX20021 options to Selector Guide 15 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 ©  2014 Maxim Integrated Products, Inc. 16 Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.