CS51411EVB

CS51411, CS51412, CS51413, CS51414 1.5 A, 260 kHz and 520 kHz, Low Voltage Buck Regulators with External CS51411, CS51412, CS51413, CS51414 PIN CONNECTIONS CS51411/3 CS51411/3 CS51412/4 18 BOOST V C BOOST 1 18 NC BOOST 1 18 NC V V IN FB V 2 17 V V 2 17 V IN C IN C V GND SW V 3 16 V V 3 16 V IN FB IN FB SHDNB SYNC V 4 15 NC V 4 15 NC IN IN Vsw 5 14 NC Vsw 5 14 NC V 6 13 GND V 6 13 GND SW SW CS51412/4 V 7 12 NC V 7 12 NC SW SW 18 SHDNB 8 11 NC BIAS 8 11 NC BOOST V C NC 9 10 SYNC NC 9 10 SHDNB V V IN FB V GND SW BIAS SHDNB PACKAGE PIN DESCRIPTION SOIC8 DFN18 Package Pin Package Pin Pin Symbol Function 1 1 BOOST The BOOST pin provides additional drive voltage to the onchip NPN power transistor. The resulting decrease in switch on voltage increases efficiency. 2 2, 3, 4 V This pin is the main power input to the IC. IN 3 5, 6, 7 V This is the connection to the emitter of the onchip NPN power transistor SW and serves as the switch output to the inductor. This pin may be subjected to negative voltages during switch off time. A catch diode is required to clamp the pin voltage in normal operation. This node can stand 1.0 V for less than 50 ns during switch node flyback. 4 8 BIAS The BIAS pin connects to the onchip power rail and allows the IC to run (CS51412/CS51414) most of its internal circuitry from the regulated output or another low voltage supply to improve efficiency. The BIAS pin is left floating if this feature is not used. 5 This pin provides the synchronization input. (CS51411/CS51413) 10 SYNC 5 10 SHDNB Shutdown bar input. This is an active low logical input, TTL compatible, (CS51412/CS51414) (CS51412/CS51414) with an internal pullup current source. The IC goes into sleep mode, drawing less than 85 A when the pin voltage is pulled below 1.0 V. This 4 8 pin may be left floating in applications where a shutdown function is not (CS51411/CS51413) (CS51411/CS51413) required. 6 13 GND Power return connection for the IC. 7 16 V The FB pin provides input to the inverting input of the error amplifier. If FB V is lower than 0.29 V, the oscillator frequency is divided by four, and FB current limit folds back to about 1 A. These features protect the IC under severe overcurrent or short circuit conditions. 8 17 V The V pin provides a connection point to the output of the error C C amplifier and input to the PWM comparator. Driving of this pin should be avoided because onchip test circuitry becomes active whenever current exceeding 0.5 mA is forced into the IC. 9, 11, 12, 14, 15, 18 NC No Connection