LX1752CLQ

LX1752 TM ® Dual Interleaving PWM Controller P RODUCTION D ATA S HEET GENERAL DESCRIPTION The LX1752 is a dual output synchronous buck controller using voltage mode PWM architecture. The single input voltage supply feature simplifies the design and offers a wide range of operation from 4.5 to 22 volts. Each PWM has a Soft-Start pin for programming the output sequencing and serves as the shutdown control. Current limit threshold is set with a single external resistor and protects the high-side and low-side MOSFETs by sensing the voltage drop generated from RDSON. Each PWM channel has its own external feedback compensation for performance optimization. Internal gate drive circuitry provides 5V for the external upper and lower N channel MOSFETS. Output voltages as low as 700mV, load currents up to 15A per phase and efficiency of 93% can be achieved with the flexible controller. Operating alone or with other LX1752’s on a bus, three multi-phase interleaving options are available: two PWM channels with 180° separation; three PWM channels at 120° or four PWM channels at 90°. This phasing is set by the tri-state input pin PSET. This architecture minimizes the input capacitor requirements. The entire power supply design occupies a small footprint with the LX1752’s low profile 28 pin, MLP package of 4x5x1mm (JEDEC MO-220). KEY FEATURES Dual PWM Controller, Synchronous Operation Voltage Mode PWM with External Compensation Single Input Supply, wide range 4.5V to 22V Precision Reference Outputs as low as 700mV Selectable PWM Frequency up to 1.5Mhz Synchronization Pin for PWM Frequency Independent and Programmable Soft Start/Enable for Power Sequencing Integrated High Current MOSFET Drivers Programmable Current Limit Lossless Current Sensing for Current Limit and Short Circuit Protection Pb-free, RoHS Compliant WWW . Microsemi . C OM IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com APPLICATIONS Multi-Output Power Supplies Video Card Power Supplies PC Peripherals Set Top Boxes Point of Load DC-DC Converters PRODUCT HIGHLIGHT VIN 4.5V to 22V PACKAGE ORDER INFO TA (°C) VIN VCCL PSET SSENX AGND VSX HOX VCX HRX VOUT LQ Plastic MLPQ 28 pin LX1752CLQ RoHS Compliant / Pb-free 0 to 85 Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1752CLQ-TR) LX1752 Part CSX LX1752 LX1752 LOX PGX EAXEAOX SYNC SHDN SYNC SHDNX RFREQ ONE OF 2 PWM SECTIONS Copyright © 2007 Rev. 1.0, 2008-07-31 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 1 LX1752 TM ® Dual Interleaving PWM Controller P RODUCTION D ATA S HEET ABSOLUTE MAXIMUM RATINGS PACKAGE PIN OUT E01 EA1SSEN1 RFREQ PSET VREF WWW . Microsemi . C OM Supply Input Voltage(VIN) .............................................................. -0.3V to 22V Supply Voltage (VCCL) .................................................................. -0.3V to 6.0V Topside Driver Supply Input Voltage (VCX) .................................... -0.3V to 28V Topside Current Sense Input (VSx) .................................................. -0.3V to 28V Current Sense Input (CSX) .................................. -0.3V(-2.0V for ≤ 50ns), to 28V Topside Driver Return Input Voltage (VHRX).... -0.3V(-2.0V for ≤ 50ns), to 28V Error Amplifier Inputs (EAX-) ........................................................ -0.3V to 5.5V Logic Inputs (SYNC, PSET, SHDNX) .............................................-0.3 to VCCL Differential Voltage: VHOX-VHRX (High Side Return)......................... -0.3V to 6V Soft Start Input (SSENX)..................................................................-0.3V to VREF Maximum LDO Output Current (VCCL) ...................................................100mA Maximum Operating Junction Temperature ................................................ 150°C Operating Temperature ....................................................................-20°C to 85°C Storage Temperature Range...........................................................-65°C to 150°C Peak Package Solder Reflow Temp (40 seconds max exposure).... 260°C (+0, -5) Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of specified terminal. x denotes respective pin designator (1 or 2). GND SYNC SHDN2 SSEN2 EA2EO2 VIN CS2 1 2 3 4 5 6 7 8 28 27 26 25 24 23 22 21 20 19 18 17 16 15 9 10 11 12 13 14 SHDN1 CS1 VS1 VC1 H01 HR1 L01 PGND L02 VCCL HR2 H02 VC2 VS2 LQ PACKAGE (Top View) THERMAL DATA MSC 1752 XXXX LQ PACKAGE MARKINGS “xxxx” Denote Date Code and Lot Identification LQ Plastic MLPQ 28-Pin THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA 27°C/W Junction Temperature Calculation: TJ = TA + (PD x θJA). The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow. RoHS / Pb-free 100% matte Tin Pin Finish FUNCTIONAL PIN DESCRIPTION Name GND SYNC Pin 1 2 Description Analog Ground. Connect this pin to a local analog ground plane. All low level signals are referenced to this ground and should return to this pin. SYNC Control Line used on the multi-channel bus. Wire OR’d negative going pulse with a common pull-up resistor. The Shutdown pin is an I/O pin which connects to an internal open drain transistor and an external pull up resistor. During a fault, this pin will be low during the discharge portion of hiccup mode, and high during the recovery (soft start) portion of hiccup mode.. Used primarily for test purposes. May be used as a system level fault monitor. Each SHDN pin requires a pull-up resistor of 500Ω to 4.7K tied to VCCL. Soft Start Enable input. Connect a capacitor from SSENx to GND to set the soft-start time, the rise time of the output voltage during start up. If grounded the PWM is disabled. Error Amplifier Inverting Input for the corresponding PWM channel denoted by “X”. Connect to the output via external network to regulate the output voltage. Error Amplifier Output – Connect to external loop compensation network for the corresponding PWM channel denoted by “X” to provide an error signal to the internal PWM comparator for duty cycle control. Controller Supply Voltage. This is the input to the internal 5V LDO. SHDNX 3, 22 LX1752 LX1752 SSENX EAX EOX VIN 4, 25 5, 24 6, 23 7 Copyright © 2007 Rev. 1.0, 2008-07-31 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 2 LX1752 TM ® Dual Interleaving PWM Controller P RODUCTION D ATA S HEET FUNCTIONAL PIN DESCRIPTION Over-Current Limit Set – connecting a resistor between CSX pin and the junction of the drain of the low-side NMOSFET and the Source of the high-side MOSFET sets the current limit threshold for the corresponding PWM channel denoted by “X”. A minimum of 200 ohms must be in series with this input. Whenever the current limit threshold is reached for 4 consecutive clock cycles the shutdown latch is set and the Soft Start capacitor is discharged through an internal resistor initiating Shutdown and then a Soft Start to generate a hiccup mode current limit. Voltage reference for high side current sense. “X” denotes corresponding phase. Connect this pin directly to the high-side MOSFET’s drain. PWM channel High-Side MOSFET Gate Driver Supply. Connect to the flying capacitor bootstrap supply to ensure proper high-side gate driver supply voltage. “X” denotes the corresponding PWM channel. High Side MOSFET Gate Driver – “X” denotes corresponding PWM channel. High Side driver return, connect this pin to the High Side MOSFET source. “X” denotes the corresponding PWM channel. Output of the +5V LDO regulator. Supplies the internal circuit and the external MOSFETs gate drivers. For 4.5V < VIN < 5.5V, this pin is connected externally to VIN. For VIN > 6V this pin supplies +5V to the internal circuit and the external MOSFETs gate drivers Connect a minimum of 4.7µF ceramic capacitor from this pin to GND. Low Side MOSFET Gate Driver – “X” denotes corresponding PWM channel. Power ground pin for the low-side MOSFET drivers. Connect low-side MOSFETs’ source directly to this pin, which connects to power ground plane The resistor value from this pin to GND sets the PWM frequency. A Tri-State logic level input that selects the phase position of the two PWM channels from the SYNC pulse. A logic low, GND, will set the PWM phases at 0 and 180 degrees. An open pin, Tri-State, will set the PWM phases at 90 and 270 degrees. A logic high, VCCL, will set the PWM phases at 120 and 240 degrees. An internally generated voltage reference of 0.8V that is buffered and brought out on this pin. If used, connect a 470pF ceramic capacitor to GND. WWW . Microsemi . C OM CSX 8, 21 VSX VCX HOX HRX 9, 20 10, 19 11, 18 12, 17 VCCL LOX PGND RFREQ PSET VREF 13 14, 16 15 26 27 28 Note: X Denotes the PWM Channel: 1 or 2 LX1752 LX1752 Copyright © 2007 Rev. 1.0, 2008-07-31 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 3 LX1752 TM ® Dual Interleaving PWM Controller P RODUCTION D ATA S HEET Unless otherwise specified, the following specifications apply over the operating ambient temperature 0°C ≤ TA ≤ 85°C except where otherwise noted and the following test conditions: VIN = 12V, VCX = 17V, HOX = 1000pF load to HRX, LOX =1000pF load to GND, VHRX = 12V, (f = 800kHz). Parameter IC ELECTRICAL CHARACTERISTICS VIN Input Voltage Operation Current Feedback Voltage IVIN EAxConnect VCCL to VIN externally No Switching Initial Accuracy; TA = 25°C 4.5V ≤ VIN ≤ 22V Switching Frequency = 800kHz to1.5Mhz Measured between 1.5V rise to 1.5V fall of HOX – HRX. Measured between HOX-HRX 1.5V rise to HOXHRX 1.5V fall. 0mA ≤ IVREF ≤ 1.0mA 6.0 4.5 0.691 0.689 6 0.700 22 5.5 0.709 0.711 80 88 0.784 92 0.800 70 10 I Source = 2mA I Sink = 100µA 3.5 0.2 IIN ISET VTRIP TCSD VCSx to VHRX = 0.2V; VPGND = 0V, Vcx to Vhrx = 5.0V Referenced to VCSX, VPGND = 0V (NOTE 5) CL = 1000pF measured between 1.5V crossings of HOX-HRX and LOX. 44 -20 50 0 150 100 1.0 30 57 20 0.816 V mA V Symbol Test Conditions Min LX1752 Typ Max Units ELECTRICAL CHARACTERISTICS WWW . Microsemi . C OM High Side Minimum Pulse Width (NOTE 3, NOTE 5) Maximum Duty Cycle Buffered Reference Voltage ERROR AMPLIFIER DC Open Loop Gain, Unity gain bandwidth (NOTE 2) High Output Voltage Low Output Voltage Input Common Mode Range Input Bias Current CURRENT SENSE CS Bias Current (Source) CS Trip Threshold Offset CS Delay (Blanking) PWMIN PWMDC VREF ns % V dB MHz V mV V nA µA mV ns ns ns AVUGBW VOH VOL OUTPUT DRIVERS – N Channel MOSFETS Drive Rise and Fall Time TR/F Dead Time – High Side to Low Side TDEAD or Low Side to High Side High Side Driver RDSON Drive High Drive Low Low Side Driver RDSON Drive High Drive Low SYNC-FREQUENCY GENERATOR Maximum Clock Frequency Minimum Clock Frequency Ramp Amplitude Frequency Stability 40 40 HOX_RDSON IHOX = 100mA (NOTE 5) IHOX = -100mA LOX_RDSON ILOX = 100mA ILOX = -100mA FMAX FMIN VRAMP RFREQ = 19.1kΩ RFREQ = 178kΩ 4.5V ≤ VIN ≤22V 1.4 180 1.5 200 1.2 ±5 4.8 3.3 Ohm 4.4 3.3 Ohm 1.6 220 MHz kHz VPP % LX1752 LX1752 Copyright © 2007 Rev. 1.0, 2008-07-31 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 4 LX1752 TM ® Dual Interleaving PWM Controller P RODUCTION D ATA S HEET Unless otherwise specified, the following specifications apply over the operating ambient temperature 0°C ≤ TA ≤ 85°C except where otherwise noted and the following test conditions: VIN = 12V, VCX = 17V, HOX = 1000pF load to HRX, LOX =1000pF load to GND, VHRX = 12V, (f = 800kHz). Parameter UVLO AND SOFT-START (SS) Start-Up Threshold (VCCL) Hysteresis (NOTE 2) SS Input Resistance SS Shutdown Threshold Soft Start Time Hiccup Mode Duty Cycle INTERNAL LDO REGULATOR Regulated Output VCCL Symbol Test Conditions LX1752 Typ Units ELECTRICAL CHARACTERISTICS (CONTINUED) WWW . Microsemi . C OM Min 3.75 0.2 Max 4.35 VCCL Rising RSS VSHDN CSS = 0.1uF; VOUT rise time from 0V to 90% of output voltage set by feedback (NOTE 2) CSS = 0.1µF; 100% * On time/Off time + On time Internal + External Load: 0mA < IVCCL < 100mA; 6V < VIN