link to page 18 link to page 20 link to page 20 LT8316 PIN FUNCTIONS VIN (Pins 1, 2, 3): Drain of the 600V Internal Startup resulting voltage determines the switching frequency FET. During startup, an internal depletion MOSFET draws and peak current limit for power delivery. Connect a power from this pin to charge the INTVCC capacitor. series R-C network to stabilize the regulator. See Loop INTV Compensation section. CC (Pin 8): Internal Gate Driver Bias Voltage. During start-up, current from the VIN pin charges this pin to 12V. IREG/SS (Pin 14): Current Regulation/Soft-Start Pin. A During operation, a linear regulator from BIAS maintains 10μA current flows out of this pin. The resulting voltage this voltage at 10V. Bypass locally with a ≥2.2μF ceramic sets the output current regulation point, as determined by ≥15V rated capacitor. an internal current regulation loop. Program the current BIAS (Pin 9): Unregulated Input Voltage for the IC. This with a resistor to GND, or connect a capacitor to imple- pin derives power from a third winding on the trans- ment soft-start. former to provide power to INTVCC. Bypass locally with SMODE (Pin 16): Standby Mode Pin. Connect this pin to a ≥100nF capacitor. INTVCC to enable Standby Mode, which reduces the mini- DCM (Pin 10): Discontinuous Conduction Mode Detector. mum switching frequency to 220Hz for ultralow quiescent This pin detects the dV/dt of the switching waveform, power consumption. Connect to GND to disable. ensuring accurate output voltage sampling and quasi- EN/UVLO (Pin 17): Enable/Undervoltage Lockout Pin. The resonant boundary-mode switching. Connect a capacitor chip will operate only if the voltage on this pin is greater with series resistance from this pin to the third winding. than the internal 1.22V reference voltage. Connect to a See Boundary Mode Detection section. resistor divider as desired, or connect to BIAS or INTVCC TC (Pin 11): Temperature Compensation Pin. This pin if UVLO functionality is not desired. presents a proportional-to-absolute-temperature (PTAT) SENSE (Pin 18): Current Sense Pin. The voltage appear- voltage, which is equal to the internal 1.22V reference ing on this pin is used for peak current-mode control and voltage at 25°C and rises with temperature by 4.1mV/°C, current limiting. Connect a current-sensing resistor from to compensate for the output rectifier diode. Connect an the main power MOSFET to GND to program the current appropriate resistor from this pin to FB. limit. Utilize a compact layout with the transformer and FB (Pin 12): Feedback Pin. The voltage appearing on this input capacitor to reduce EMI and voltage spikes. pin is sampled and regulated to equal the internal 1.22V GATE (Pin 19): Gate Driver Output. Connect this pin to the reference voltage. Connect this pin to a resistor divider gate of the main power MOSFET for the flyback converter. from the third winding to regulate the output voltage. GND (Pins 15, 20, 21): Ground. Solder the exposed padVC (Pin 13): Loop Compensation Pin. An internal GM (Pin 21) to a ground plane for heat sinking. transconductance amplifier feeds this pin with an error current depending on the sampled FB voltage. The Rev. 0 For more information www.analog.com 7 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Typical Application Related Parts