EMT3571|18V 3A 500kHz Synchronous Step-Down DC/DC Converter

EMT3571|18V 3A 500kHz Synchronous Step-Down DC/DC Converter



18V 3A 500kHz Synchronous Step-Down DC/DC Converter



General​​ Description​​ ​​ 

The​​ EMT3571​​ is a high efficiency, 3A current mode synchronous step-down DC/DC converter with a wide input voltage range from 4.7V to 18V. The device integrates high side and low side MOSFETs to achieve high efficiency conversion. The current mode architecture supports fast transient response and internal compensation. The​​ EMT3571​​ provides complete fault protection including input undervoltage lockout, output short circuit protection, over current protection, and thermal shutdown. The switching frequency is internally set at 500kHz.​​ EMT3571N and​​ EMT3571A have different operation modes:

  • EMT3571N is automatic PSM/PWM mode

  • EMT3571A is Forced PWM mode

To improve the light load efficiency,​​ EMT3571N has proprietary light load power saving mode (PSM) to minimize the switching loss by reducing the switching frequency. The​​ EMT3571​​ is available in the SOT23_6L​​ .




  • Input Voltage Range from 4.7V to 18V

  • Adjustable Output Voltage from 0.8V to 12V

  • Support 100% Duty Cycle Operation

  • 500kHz Switching Frequency

  • Built-in 110mΩ/60mΩ Power Switch

  • 3A Continuous Output Current

  • High Efficiency up to 95%

  • Internal 1msec Soft-Start

  • Peak Current Mode Operation

  • Over-temperature Protection

  • Input Under Voltage Lockout (UVLO)

  • Cycle-by-Cycle Current Limit Protection

  • Over-Load and Short Circuit Protection

  • Thermal Shutdown Protection

  • Available in a Small SOT23_6L Package

  • Pb-Free RoHS Compliant




  • Wireless and DSL Card

  • Portable/Handheld Device

  • STB, TV, Sound Bar, MP3 Player

  • Microprocessor and DSP Core Supply








Typical Application Circuit














Ordering Information

























Y= Year, WW = Week, xx =​​ ​​ Manufacture Control Code




Pin Configuration












Pin Description















Absolute Maximum Rating​​ (Reference to GND) (Note1)


VIN, SW Voltage ​​​​ ------------------------------------ +20V

Dynamic VSW​​ in 10ns Duration ​​​​ ------------------- ​​ –3V to VIN+3V

BS-SW Voltage ​​​​ -------------------------------------- ​​ +6V

FB, EN Voltage ​​​​ -------------------------------------- ​​ +6V

Junction Temperature Range ​​ ​​​​ ---------------------- ​​ -40oC to +150°C

Storage Temperature Range ​​ ​​ ​​​​ ---------------------- ​​ -65oC to +150°C

Lead Temperature (Soldering 10s) ​​ ​​ ​​​​ -------------- ​​ +260°C

ESD Classification ​​ ​​​​ --------------------------------- ​​ Class


Recommend Operating Conditions​​ (Note2)


Input Voltage (VIN) ​​​​ --------------------------------- ​​ + 4.7V V to +18V

Operating Temperature Range ​​​​ --------------------- ​​ -40°C to +85°C



Thermal information (Note3)


Maximum Power Dissipation(TA=+25°C )

SOT23_6L ​​​​ --------------------------------------------- ​​ .1.25W

Thermal Resistance (θJA) ​​​​ ----------------------------- ​​ 136.68°C/W​​ 

Thermal Resistance (θJC) ​​​​ ----------------------------- ​​ 81.68°C/W​​ 

Thermal Resistance (θJA) ​​​​ ----------------------------- ​​ ​​ 94.4°C/W​​ 

Thermal Resistance (θJC) ​​​​ ----------------------------- ​​ 47.6°C/W


Note (1): Stress exceeding those listed “Absolute Maximum Ratings” may damage the device.​​ 

Note (2): The device is not guaranteed to function outside of the recommended operating conditions.​​ 

Note (3): Measured on JESD51-7, 4-Layer PCB.​​ 

Note (4):The maximum allowable power dissipations a function of the maximum junction temperature TJ_MAX, the junction to ambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD_MAX= (TJ_MAX-TA)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage.






Functional Block Diagram























Electrical Characteristics

Recommended Operating Conditions, TA​​ = +25°C, VIN=12V, unless otherwise noted.













































CIN=10µF, COUT=44µF, L=6.8µH for VOUT=5V; L=4.7µH for VOUT​​ 3.3V; L=2.2µH for VOUT=1.2V, TA​​ =+25℃