LX13088CLD

LX13088 TM ® Dual 1A Step-Down Converters P RODUCTION D ATASHEET KEY FEATURES • Outputs can be set from 1V to 3.6V @ 1A • No Rectifier Diode required • 1.3MHz Switching • 180° Phase Shifted Switching • Optional External Clocking (2x clock required) • Light load Pulse Skipping • Enable/Sleep state • Internal Soft Start • Open-drain Power On Reset Monitors Input and Outputs • Discharge Before-Turn-On • Peak Over-Current Protection • Short Circuit Protection • Over Temperature Shutdown APPLICATIONS • Hard Disk Drives • Set- Top Boxes DESCRIPTION The LX13088 is a highly integrated dual output voltage regulator ideal for low power applications that require minimal board space. The two current mode buck converters include integrated high side control switches, synchronous rectifiers, and internal compensation. The outputs of each converter are both rated for up to 1A, and the output voltages are adjustable using external resistive dividers. The LX13088 step down converters operate at 1.3MHz fixed switching frequency under normal load, reducing external output filter component values and size. Under light load conditions, the converters operate in a pulse-skipping mode for improved efficiency. The LX13088 incorporates out of phase switching, where converter 2 switches 180° out of phase from converter 1 in order to minimize the input ripple effects. The controller also features an E/S pin that provides an enable input function, or allows the converter to be synchronized to an external clock. With the E/S input held low, the LX13088 draws less than 10uA. Both converters have controlled soft start, in addition to power up sequencing. In the start-up sequence, the output of converter 1 is designed to precede the output of converter 2. Power On Reset function is provided by means of an open-drain output at the POR pin. The Power On Reset function monitors the voltages at the VMON, FB1 and FB2 pins, and pulls low if any of these voltages drop below the stated POR threshold. The POR is internally deglitched and provides a delayed recovery and reset time. The LX13088 provides peak over current protection, short circuit protection and thermal shutdown. Discharge-BeforeTurn-On discharges the outputs completely before soft starting to always bring them up in the proper sequence at start up or after a POR event. W WW . Microsemi . C OM IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com Product Highlight LX13088 LX13088 PACKAGE ORDER INFO THERMAL DATA TA (°C) 0 to +70 LD Plastic 3x3 mm DFN 10-pin RoHS Compliant / Pb-free θJA = 33 °C/W THERMAL RESISTANCE-JUNCTION TO AMBIENT LX13088CLD Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX13088CLD-TR) 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. Page 1 Copyright © 2010 Rev. 1.1, 2010-06-08 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 LX13088 TM ® Dual 1A Step-Down Converters P RODUCTION D ATASHEET ABSOLUTE MAXIMUM RATINGS PVIN, AVIN to AGND, PGND...................................................................... -0.3 to +7.0 V SW1 and SW2 to AGND, PGND .................................................. PGND -2V to xVIN+2V All other pins to AGND.................................................................... -0.3V to xVIN + 0.3V Operating Junction Temperature Range .......................................................... 00C to 1500C Storage Temperature Range..........................................................................–650C to 1500C 0 Package Peak Temp. for Solder Reflow (40 seconds maximum exposure) .. 260°C (+0 -5) C Notes: 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. PGND must be wired to AGND externally. PACKAGE PIN OUT W WW . Microsemi . C OM LD PACKAGE (Top View) Marking 3088 Date/Lot Code MSC RoHS / Pb-free 100% Matte Tin Finish FUNCTIONAL PIN DESCRIPTION Name FB2 Pin # 1 Description Feedback from VO2. Connect voltage divider to the load side of VO2 output inductor-capacitor filter. Analog Input. Input to power the internal circuitry of the device, connect to PVIN through a 10Ω resistor and bypass through a 1μF ceramic capacitor between this pin and PGND, as close to the LX13088 as possible. Control MOSFET switch power inputs. Connect a 10µF ceramic capacitor between this pin and PGND, as close to the LX13088 as possible. Converter 2 synchronous buck switching output. Connect to VO2 inductor. Power Ground Connection. Synchronous rectifier MOSFET source. Provide a star connection between this pin, VO1, VO2 filter capacitor returns, VIN input capacitor return, and AGND. Keep the star connection as close to the LX13088 IC as possible. Converter 1 synchronous buck switching output. Connect to VO1 inductor. Enable/Synchronization. Pulling this pin high statically enables the LX13088 and pulling the pin low statically will shut down the LX13088. Applying a pulse to this pin will synchronize SW1 and SW2 switching frequency to ½ the external clock frequency. Power On Reset output pin. Monitors FB1, FB2 output voltage levels and VIN. POR is pulled low if an output voltage droop is detected on FB1 or FB2 or VIN, and is Hi-Z during normal operation. Voltage Monitor – Supervisor for one external voltage (could be input voltage). The POR output is triggered if this output falls below the VMON threshold. Feedback from VO1. Connect voltage divider to the load side of VO1 output inductor-capacitor filter. Analog Ground. Connect the exposed pad on the bottom of the package to the GND plane for a thermal heat sink. Page 2 AVIN 2 PVIN 3 SW2 4 PGND SW1 E/S POR VMON FB1 AGND 5 6 7 8 9 10 PAD LX13088 LX13088 Copyright © 2010 Rev. 1.1, 2010-06-08 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 LX13088 TM ® Dual 1A Step-Down Converters P RODUCTION D ATASHEET ELECTRICAL CHARACTERISTICS Unless otherwise specified, the following specifications apply over the operating ambient temperature of 00C < Temp