XXRR7766220033//55//88 40V, 3/5/8A Synchronous Step Down COT Regulator 40V, 3/5/8A Synchronous Step Down COT Regulator February 2015 Rev. 1A GENERAL DESCRIPTION EVALUATION BOARD MANUAL The XR76203, XR76205 and XR76208 are EVALUATION BOARD MANUAL synchronous step-down regulators combining the controller, drivers, bootstrap diode and MOSFETs in a single package for point-of-load supplies. The XR76203, XR76205 and XR76208 have load current ratings of 3A, 5A and 8A respectively. A wide5V to 40V input voltage range allows for single supply operation from industry standard 24V 10%, 18V- 36V, and rectified 18VAC and 24VAC rails. With a proprietary emulated current mode Constant On-Time (COT) control scheme, the XR76203, XR76205 and XR76208 provide extremely fast line and load transient response using ceramic output capacitors. They require no loop compensation, simplifying circuit implementation and reducing overall component count. The control loop also FEATURES provides 0.07% load and 0.15% line regulation and Controller, drivers, bootstrap diode, MOSFETs maintains constant operating frequency. A selectable integrated in one package power saving mode allows the user to operate in 3/5/8A Step Down Regulator discontinuous conduction mode (DCM) at light - Wide 5V to 40V Input Voltage Range current loads thereby significantly increasing the - 0.6V Adjustable Output Voltage converter efficiency. Proprietary Constant On-Time Control A host of protection features, including over-current, - No Loop Compensation Required over-temperature, short-circuit and UVLO, helps - Ceramic Output Cap. Stable operation achieve safe operation under abnormal operating - Programmable 200ns-2s On-Time conditions. - Constant 400kHz-600kHz freq. The XR76203/5/8 are available in a RoHS-compliant, - Selectable CCM or CCM/DCM Operation green/halogen-free space-saving QFN 5x5mm 30-pin 5x5mm QFN package package. CSNB 0.56nF RSNB 1 Ohm CBST 1uF DZ MMSZ4685 RZ 10k RBST 0 Ohm VIN+ 24VIN 2-3 --> DCM/CCM C13 R3 30.1k 3 3 J1 2 2 1 R4 35.7k 1 C15 C14 C1 C2 C3 C4 T3 1-2 --> CCM 10uF/50V 10uF/50V 10uF/50V T4 VIN- SW RLIM 5.49k 1 22 ILIM PVIN EN/MODE 2 21 EN PVIN RON 28k 3 20 TON SW CSS 47nF 4 U1 19 SS PGND XR76208 5 18 PGOOD PGND SS 6 17 FB PGND 7 16 AGND PGND PWRGD 15 PGND FB VCC R5 10k IHLP-5050-01 VOUT+ 400kHz, 3.3V 0-8A 2.2uH T1 C7 C8 C5 C6 C16 C18 C9 C10 C11 C12 C17 C19 SW 47uF/10V 47uF/10V 47uF/10V T2 VOUT- CIN 0.1uF C20 PVIN 0.1uF CFF 0.27nF R6 OPEN CVCC 4.7uF RFF R1 0 Ohm 9.09k VCC FB FB R2 2k AGND Fig. 1: XR76208 Evaluation Board Schematics Exar Corporation www.exar.com 48720 Kato Road, Fremont CA 94538, USA Tel. +1 510 668-7000 Fax. +1 510 668-7001 34 PVIN PAD 33 SW PAD 32 PGND PAD 8 31 VIN AGND PAD 9 30 VCC BST 10 29 AGND SW 11 28 SW PVIN 12 27 SW PVIN 13 26 SW PVIN 14 25 SW PVIN 24 PVIN 23 PVINXXRR7766220033//55//88 40V, 3/5/8A Synchronous Step Down COT Regulator 40V, 3/5/8A Synchronous Step Down COT Regulator PIN ASSIGNMENT Fig. 2: XR76203/5/8 Pin Assignment 2015 Exar Corporation 2/13 Rev. 1A