XR76121 20A Synchronous Step-Down COT Regulators Description FEATURES The XR76121 is a synchronous step-down regulator combining the 20A step-down regulator controller, drivers, bootstrap diode and MOSFETs in a single package 4.5V to 5.5V low V operation IN 5V to 22V wide single input voltage for point-of-load supplies. The XR76121 has a load current rating 3V to 22V operation with external of 20A. A wide 5V to 22V input voltage range allows for single supply 5V bias operation from industry standard 5V, 12V and 19.6V rails. 0.6V adjustable output voltage With a proprietary emulated current mode constant on-time (COT) Proprietary constant on-time control control scheme, the XR76121 provides extremely fast line and No loop compensation required Ceramic output capacitor stable load transient response using ceramic output capacitors. They operation require no loop compensation, simplifying circuit implementation Programmable 70ns-1s on-time and reducing overall component count. The control loop also Constant 200kHz-1MHz frequency provides 0.1% load and 0.1% line regulation and maintains constant Selectable CCM or CCM/DCM operating frequency. A selectable power saving mode, allows the user operation to operate in discontinuous mode (DCM) at light current loads thereby Power-good flag with low impedance when significantly increasing the converter efficiency. power removed Precision enable A host of protection features, including overcurrent, over temperature, Programmable soft-start overvoltage, short-circuit, open feedback detect and UVLO, helps 5mm x 6mm QFN package achieve safe operation under abnormal operating conditions. APPLICATIONS The XR76121 is available in a RoHS compliant, green/halogen-free Servers space-saving 5mm x 6mm QFN package. Distributed power architecture Point-of-load converters FPGA, DSP and processor supplies Base stations, switches/routers Typical Application 100 C L1 V 600kHz ENABLE BST OUT 98 EN BST 96 V IN 94 VIN SW 92 R C FF LIM PVIN ILIM 90 R1 POWER GOOD 88 R FF PGOOD 86 800kHz XR76121 84 VCC FB C IN C OUT R 82 5.0V V OUT SS FCCM 80 3.3V R1 R2 2.5V 78 1.8V TON VSNS 76 1.5V R ON 74 1.2V AGND PGND R2 72 C C VCC SS 1.0V 70 0.1 5.1 10.1 15.1 20.1 I ( ) A OUT Figure 1. Typical Application Figure 2. Efficiency REV1D 1/18 Efciency (%)XR76121 Absolute Maximum Ratings Operating Conditions These are stress ratings only and functional operation PV ......................................................................3V to 22V IN of the device at these ratings or any other above those V .....................................................................4.5V to 22V IN indicated in the operation sections of the specifications V ...................................................................4.5V to 5.5V CC below is not implied. Stresses beyond those listed under (2) absolute maximum ratings may cause permanent damage SW, ILIM ..........................................................-1V to 22V to the device. Exposure to any absolute maximum rating (2) PGOOD, TON, SS, EN .................................-0.3V to 5.5V condition for extended periods may affect device reliability (3) Switching frequency ................................... 200kHz-1MHz and lifetime. Junction temperature range (T ).................. -40C to 125C PV , V -0.3V to 25V J IN IN ......................................................................... Package power dissipation max at 25C .....................4.1W V -0.3V to 6.0V CC .................................................................................. (4) (1) Package thermal resistance 24C/W BST ................................................................-0.3V to 31V JA .................................... NOTES: BST-SW ............................................................. -0.3V to 6V 1. No external voltage applied. 2. SW pins DC range is -1V, transient is -5V for less than 50ns. (1)(2) SW, ILIM ........................................................ -1V to 25V 3. Recommended. 4. Measured on MaxLinear evaluation board. All other pins .........................................-0.3V to V + 0.3V CC Storage temperature .................................... -65C to 150C Junction temperature ................................................. 150C Power dissipation ...................................... Internally limited Lead temperature (soldering, 10 second) .................. 300C ESD rating (HBM human body model) ....................... 2kV ESD rating (CDM charged device model) .................. 1kV ESD rating (MM machine model) .............................200V Electrical Characteristics Specifications are for operating junction temperature of T = 25C only limits applying over the full operating junction J temperature range are denoted by a . Typical values represent the most likely parametric norm at T = 25C, and are J provided for reference purposes only. Unless otherwise indicated, V = 12V, SW = AGND = PGND = 0V, C = 4.7uF. IN VCC Symbol Parameter Conditions Min Typ Max Units Power Supply Characteristics V regulating 5 12 22 CC V Input voltage range V IN V tied to V 4.5 5.0 5.5 CC IN I V supply current Not switching, V = 12V, V = 0.7V 0.8 1.3 mA VIN IN IN FB Not switching, V = V = 5V, CC IN I V quiescent current 0.8 1.3 mA VCC CC V = 0.7V FB f = 600kHz, R = 49.9k, ON I V supply current 17 mA VIN IN V = 0.58V FB I Shutdown current Enable = 0V, PV = V = 12V 1 A OFF IN IN Enable and Undervoltage Lock-Out UVLO V EN pin rising threshold 1.8 1.9 2.0 V IH EN V EN pin hysteresis 60 mV EN HYS V UVLO start threshold, rising edge 4.00 4.25 4.40 V CC V UVLO hysteresis 100 170 mV CC REV1D 2/18