DATASHEET RAA212421 FN9309 Rev.3.00 3V to 40V Input, 1.1A Synchronous Buck Regulator with Integrated 500mA LDO Jul 8, 2019 The RAA212421 is a dual-output regulator combining a Features 3V to 40V input, 1.1A synchronous buck converter with Wide input voltage range of 3V to 40V a 500mA LDO featuring fast transient response. The Synchronous operation for high efficiency combination of two high-performance power supplies in one compact 3x6mm package provide an easy-to-use, Integrated high-side and low-side NMOS devices high-efficiency compact solution. Selectable PFM or PWM mode at light loads The wide VIN buck regulator of the RAA212421 Internal fixed frequency (500kHz) or adjustable integrates both high-side and low-side nMOSFETs and switching frequency (300kHz to 2MHz) features a PFM mode for improved efficiency at light load. This feature can be disabled if forced PWM mode is Continuous output current up to 1.1A desired. It can use internal or external compensation, Internal or external soft-start which minimizes the required external components, Power-good and enable functions reduces BOM count and complexity of design. The part switches at a default frequency of 500kHz however, it can 500mA low dropout linear regulator also be programmed using an external resistor from 1.8V to 6V input 300kHz to 2MHz. Other features include programmable soft-start, hiccup mode overcurrent protection, thermal 1.8% V accuracy ensured over line, load, and OUT shutdown, and power-good. T = -40C to +125C J The LDO also features state-of-the-art internal Very low 45mV dropout voltage at V = 2.5V OUT compensation that allows it to achieve very fast load Excellent PSRR over wide frequency range transient response. The device provides an output Programmable output soft-start time accuracy of 1.8% V accuracy over all load, line, and OUT temperature variations (T = -40C to +125C). Other J Very fast transient response features include soft-start and enable that allow the LDO Current limit protection to be placed into low quiescent current shutdown mode. Applications The part is available in a small Pb-free 3mmx6mm DFN plastic package with a full-range industrial temperature Industrial control, medical devices, portable of -40C to +125C. instrumentation, distributed power supplies, cloud infrastructure Related Literature For a full list of related documents, visit our website: RAA212421 device page L VIN1 1 + EN1 LX1 SYNC1 + 100 C BOOT FS1 VIN1 COMP1 95 R 1 BOOT1 C FF SS1 C 90 OUT1 VOUT1 FB1 VCC1 85 RAA212421 C R - VCC 2 - GND1 80 PG1 75 70 VIN2 VOUT2 + VIN2 65 VIN1 = 12V + VOUT2 R EN2 3 C PB 60 C OUT2 VIN1 = 24V VIN2 SS2 FB2 VOUT2 55 VIN1 = 33V C GND2 SS2 R 50 4 - - 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 Output Load(A) Figure 2. Efficiency vs Load, PFM, V = 5V, L = 22H Figure 1. Typical Application OUT 1 FN9309 Rev.3.00 Page 1 of 34 Jul 8, 2019 Efficiency (%)RAA212421 Contents 1. Overview . 3 1.1 Typical Application Circuits 3 1.2 Block Diagram 4 1.3 Ordering Information . 5 1.4 Pin Configurations . 5 1.5 Pin Descriptions . 5 2. Specifications . 7 2.1 Absolute Maximum Ratings 7 2.2 Thermal Information 7 2.3 Recommended Operating Conditions 7 2.4 Electrical Specifications . 8 3. Typical Performance Curves 11 3.1 Buck Efficiency Curves 11 3.2 Buck Measurements 13 3.3 LDO Characteristics . 16 4. Functional Description 20 4.1 Power-On Reset (Buck) 20 4.2 Soft-Start . 20 4.3 Power-Good (Buck) . 20 4.4 PWM Control Scheme (Buck) . 21 4.5 Light Load Operation 21 4.6 Output Voltage Selection . 22 4.7 Protection Features . 23 4.8 Input Voltage Requirement (LDO) 24 4.9 Enable Operation (LDO) . 24 5. Application Guidelines 25 5.1 Simplifying the Design . 25 5.2 Operating Frequency 25 5.3 Minimum On/Off-Time Limitation . 25 5.4 Synchronization Control 26 5.5 Output Inductor Selection 26 5.6 Output Capacitor Selection (Buck) . 26 5.7 Loop Compensation Design 27 5.8 External Capacitor Requirements (LDO) . 30 5.9 Power Dissipation and Thermals . 30 6. Layout Considerations 31 7. Revision History 32 8. Package Outline Drawing 33 FN9309 Rev.3.00 Page 2 of 34 Jul 8, 2019