DatasheetsPDF.com

RT7257J Dataheets PDF



Part Number RT7257J
Manufacturers Richtek
Logo Richtek
Description Synchronous Step-Down Converter
Datasheet RT7257J DatasheetRT7257J Datasheet (PDF)

Design Tools ® RT7257J 3A, 18V, 340kHz Synchronous Step-Down Converter General Description The RT7257J is a high efficiency, monolithic synchronous step-down DC/DC converter that can deliver up to 3A output current from a 4.5V to 18V input supply. The RT7257J's current mode architecture and external compensation allow the transient response to be optimized over a wide input voltage range and loads. Cycle-by-cycle current limit provides protection against shorted outputs, and soft-start elimina.

  RT7257J   RT7257J


Document
Design Tools ® RT7257J 3A, 18V, 340kHz Synchronous Step-Down Converter General Description The RT7257J is a high efficiency, monolithic synchronous step-down DC/DC converter that can deliver up to 3A output current from a 4.5V to 18V input supply. The RT7257J's current mode architecture and external compensation allow the transient response to be optimized over a wide input voltage range and loads. Cycle-by-cycle current limit provides protection against shorted outputs, and soft-start eliminates input current surge during start-up. The RT7257J also provides under voltage protection and thermal shutdown protection. The low current (<3μA) shutdown mode provides output disconnection, enabling easy power management in battery-powered systems. The RT7257J is available in an SOP-8 (Exposed Pad) package. Marking Information RT7257JCHZSP : Product Number RT7257JCH ZSPYMDNN YMDNN : Date Code Features  ±1.5% High Accuracy Reference Voltage  4.5V to 18V Input Voltage Range  3A Output Current  Integrated N-MOSFET Switches  Current Mode Control  Fixed Frequency Operation : 340kHz  Output Adjustable from 0.8V to 15V  Stable with Low ESR Ceramic Output Capacitors  Up to 95% Efficiency  Programmable Soft-Start  Cycle-by-Cycle Over Current Protection  Input Under Voltage Lockout  Output Under Voltage Protection  Thermal Shutdown Protection  RoHS Compliant and Halogen Free Applications  Wireless AP/Router  Set-Top-Box  Industrial and Commercial Low Power Systems  LCD Monitors and TVs  Green Electronics/Appliances  Point of Load Regulation of High-Performance DSPs Simplified Application Circuit VIN Chip Enable CIN CSS VIN BOOT RT7257J SW EN SS FB GND COMP CBOOT L VOUT CC RC R1 COUT R2 CP Open Copyright ©2018 Richtek Technology Corporation. All rights reserved. DS7257J-04 March 2018 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT7257J Ordering Information RT7257JCH Package Type SP : SOP-8 (Exposed Pad-Option 2) Lead Plating System Z : ECO (Ecological Element with Halogen Free and Pb free) Note : Richtek products are :  RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.  Suitable for use in SnPb or Pb-free soldering processes. Pin Configurations (TOP VIEW) BOOT VIN SW GND 8 27 GND 36 9 45 SS EN COMP FB SOP-8 (Exposed Pad) Functional Pin Description Pin No. Pin Name Pin Function 1 BOOT Bootstrap for High Side Gate Driver. Connect a 0.1μF or greater ceramic capacitor from BOOT to SW pins. 2 VIN Power Input. The input Voltage range is from 4.5V to 18V. Connect two 10μF or larger ceramic capacitors from the VIN to GND. 3 SW Switch Node. Connect this pin to an external L-C filter. 4, 9 (Exposed Pad) GND Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. 5 FB Feedback Input. It is used to regulate the output of the converter to a set value via an external resistive voltage divider. Compensation Node. COMP is used to compensate the regulation control 6 COMP loop. Connect a series RC network from COMP to GND. In some cases, an additional capacitor from COMP to GND is required. Enable Input. A logic high enables the converter; a logic low forces the 7 EN RT7257J into shutdown mode reducing the supply current to less than 3μA. Attach this pin to VIN with a 100kΩ pull-up resistor for automatic startup. Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor 8 SS from SS to GND to set the soft-start period. A 0.1μF capacitor sets the soft-start period to 13.5ms. Copyright ©2018 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS7257J-04 March 2018 Function Block Diagram RT7257J VIN Internal Regulator Oscillator Shutdown Comparator VA VCC 1.2V + Foldback Control - 0.4V + Lockout 5kΩ Comparator EN - UV Comparator 1.8V + VCC 6µA SS 0.8V ++EA - Current Sense Slope Comp Amplifier + - RSENSE VA S + R Current Comparator Q Q 110mΩ 90mΩ BOOT SW GND FB COMP Copyright ©2018 Richtek Technology Corporation. All rights reserved. DS7257J-04 March 2018 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT7257J Absolute Maximum Ratings (Note 1)  Supply Input Voltage, VIN ----------------------------------------------------------------------------------------- −0.3V to 20V  Switch Voltage, SW ------------------------------------------------------------------------------------------------ −0.3V to (VIN + 0.3V)  VBOOT − VSW ---------------------------------------------------------------------------------------------------------- −0.3V to 6V  Other Pins Voltage ------------------------------------------------------------------------------------------------- −0.3V to 20V  Power Dissipation, PD @ TA = 25°C SOP-8 (Exposed P.


RT7257G RT7257J RT7258


@ 2014 :: Datasheetspdf.com :: Semiconductors datasheet search & download site.
(Privacy Policy & Contact)