1 |
3 |
SW |
Switch pin |
The drain terminal of the internal power MOSFET. |
2 |
4 |
VIN |
Input supply pin |
Nominal operating range: 3.1 V to 75 V. |
3 |
5 |
VCC |
Bias regulator output, or input for external bias supply |
VCC tracks VIN up to 6.9 V. Above VIN = 6.9 V, VCC is regulated to 6.9 V. A 0.47-µF or greater ceramic decoupling capacitor is required. An external voltage (7 V – 12 V) can be applied to this pin which disables the internal VCC regulator to reduce internal power dissipation and improve converter efficiency. |
4 |
6 |
GND |
Ground |
Internal reference for the regulator control functions and the power MOSFET current sense resistor connection. |
5 |
7 |
RT |
Oscillator frequency programming and optional synchronization pulse input |
The internal oscillator is set with a resistor, between this pin and the GND pin. The recommended frequency range is 50 KHz to 1.5 MHz. The RT pin can accept synchronization pulses from an external clock. A 100-pF capacitor is recommended for coupling the synchronizing clock to the RT pin. |
6 |
8 |
FB |
Feedback input from the regulated output voltage |
This pin is connected to the inverting input of the internal error amplifier. The 1.26-V reference is internally connected to the non-inverting input of the error amplifier. |
7 |
1 |
COMP |
Open drain output of the internal error amplifier |
The loop compensation network should be connected between the COMP pin and the FB pin. COMP pull-up is provided by an internal 5-kΩ resistor which may be used to bias an opto-coupler transistor (while FB is grounded) for isolated ground applications. |
8 |
2 |
EN |
Enable / Undervoltage Lock-Out / Shutdown input |
An external voltage divider can be used to set the line undervoltage lockout threshold. If the EN pin is left unconnected, a 6-µA pull-up current source pulls the EN pin high to enable the regulator. |
NA |
EP |
EP |
Exposed Pad, WSON only |
Exposed metal pad on the underside of the package with a resistive connection to pin 6. It is recommended to connect this pad to the PC board ground plane in order to improve heat dissipation. |