RT7296FGJ8F

RT7296F 3A, 17V Current Mode Synchronous Step-Down Converter General Description Features The RT7296F is a high-efficiency, 3A current mode  4.5V to 17V Input Voltage Range synchronous step-down DC/DC converter with a wide  3A Output Current input voltage range from 4.5V to 17V. The device  Internal N-Channel MOSFETs integrates 80m low-side  Current Mode Control MOSFETs to achieve high efficiency conversion. The  Fixed Switching Frequency : 500kHz current architecture supports fast  Synchronous to External Clock : 200kHz to 2MHz transient response and internal compensation. A  Cycle-by-Cycle Current Limit cycle-by-cycle current limit function provides protection  Internal Soft-Start Function against  Power Save mode at light load input  Power Good Indicator under-voltage lockout, output under-voltage protection,  Input Under-Voltage Lockout over-current protection, and thermal shutdown. The  Output Under-Voltage Protection PWM frequency is adjustable by the EN/SYNC pin. The  Thermal Shutdown high-side mode control shorted complete output. protection and The 30m RT7296F functions such provides as RT7296F is available in the TSOT-23-8 (FC) package. Ordering Information RT7296F Package Type J8F : TSOT-23-8 (FC) Lead Plating System G : Green (Halogen Free and Pb Free) Applications  Industrial and Commercial Low Power Systems  Computer Peripherals  LCD Monitors and TVs  Set-top Boxes Marking Information Note : Richtek products are :   08= : Product Code DNN : Date Code 08=DNN RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Simplified Application Circuit VIN VIN RT7296F BOOT C3 C1 L1 VOUT SW Enable EN/SYNC R5 PVCC C2 R3 PG Copyright © 2016 Richtek Technology Corporation. All rights reserved. DS7296F-02 May 2016 R1 FB R2 C4 GND is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT7296F Pin Configurations PVCC EN/SYNC BOOT 8 7 6 5 2 3 4 VIN SW GND PG FB (TOP VIEW) TSOT-23-8 (FC) Functional Pin Description Pin No. Pin Name Pin Function 1 PG Power Good Output. This pin is an open drain which can be connected to PVCC by a resistor. If output voltage achieve 90% of the normal voltage, the PG pin will go high after 400s delay. 2 VIN Power Input. Support 4.5V to17V Input Voltage. Must bypass with a suitable large ceramic capacitor at this pin. 3 SW Switch Node. Connect to external L-C filter. 4 GND System Ground. 5 BOOT Bootstrap Supply for High-Side Gate Driver. Connect a 0.1F ceramic capacitor between the BOOT and SW pins. 6 EN/SYNC Enable Control Input. High = Enable. Apply an external clock to adjust the switching frequency. If using pull high resistor connected to VIN, the recommended value range is 60k to 300k. 7 PVCC 5V Bias Supply Output. Connect a minimum of 0.1F capacitor to ground. 8 FB Feedback Voltage Input. The pin is used to set the output voltage of the converter to regulate to the desired voltage via a resistive divider. Feedback reference = 0.8V. Copyright © 2016 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS7296F-02 May 2016 RT7296F Function Block Diagram PG VIN PVCC Internal Regulator Current Sense UVLO BOOT UVLO Shutdown Comparator - EN/SYNC 1.4V + 0.4V + BOOT Logic & Protection Control Power Stage & Deadtime Control SW - UV Comparator HS Switch Current Comparator 1pF 50pF 400k FB 0.807V Internal SS + EA + Oscillator LS Switch Current Comparator Current Sense GND Slope Compensation Operation Under-Voltage Lockout Threshold Operating Frequency and Synchronization The IC includes an input Under Voltage Lockout The internal oscillator runs at 500kHz (typ.) when the Protection (UVLO). If the input voltage exceeds the EN/SYNC pin is at logic-high level (>1.6V). If the EN UVLO rising threshold voltage (3.9V), the converter pin is pulled to low-level over 8s, the IC will shut down. resets and prepares the PWM for operation. If the input The RT7296F can be synchronized with an external voltage falls below the UVLO falling threshold voltage clock ranging from 200kHz to 2MHz applied to the (3.25V) during normal operation, the device stops EN/SYNC pin. The external clock duty cycle must be switching. The UVLO rising and falling threshold from 20% to 80% with logic-high level = 2V and voltage includes a hysteresis to prevent noise caused logic-low level = 0.8V. reset. Internal Regulator Chip Enable The internal regulator generates 5V power and drive The EN pin is the chip enable input. Pulling the EN pin internal circuit. When VIN is below 5V, PVCC will drop low (0.1F) between PVCC and mode, the RT7296F’s quiescent current drops to lower GND is required. than 1A. Driving the EN pin high (>1.6V) will turn on the device. Internal Soft-Start Function The RT7296F provides internal soft-start function. The soft-start function is used to prevent large inrush current while converter is being powered-up. The soft-start time (VFB from 0V to 0.8V) is 1.5ms. Copyright © 2016 Richtek Technology Corporation. All rights reserved. DS7296F-02 May 2016 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT7296F Absolute Maximum Ratings (Note 1)  Supply Input Voltage, VIN ----------------------------------------------------------------------------------- 0.3V to 20V  Switch Voltage, SW -------------------------------------------------------------------------------------------- 0.3V to VIN + 0.3V