NOT RECOMMENDED FOR NEW DESIGN CONTACT US AP3512E 18V, 2A SYNCHRONOUS DC-DC BUCK CONVERTER Description Pin Assignments The AP3512E is a 500kHz fixed frequency, current mode, PWM (Top View) synchronous buck (step-down) DC-DC converter, capable of driving a 2A load with high efficiency, excellent line and load regulation. The AP3512E exhibits high efficiency at light load. The device integrates BS 1 SS 8 N-channel power MOSFET switch with low on-resistance. Current mode control provides fast transient response and cycle-by-cycle current limit. IN 2 7 EN The AP3512E employs complete protection to ensure system SW 3 6 COMP security, including output Over Voltage Protection, input Under Voltage Lock Out, programmable Soft-start, Over Temperature GND 4 5 FB Protection and hiccup mode Short Circuit Protection. This IC is available in SO-8 and SO-8EP packages. SO-8 Features (Top View) Input Voltage Range: 4.5V to 18V Fixed 500kHz Frequency BS 8 SS High Efficiency at Light Load 1 Output Current: 2A IN 2 EN 7 Current Mode Control EP Built-In Over Current Protection COMP SW 3 6 Built-In Thermal Shutdown Function Built-In UVLO Function GND 5 FB 4 Built-In Over Voltage Protection Programmable Soft-Start Hiccup Mode SCP Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) SO-8EP Halogen and Antimony Free. Green Device (Note 3) Applications Monitor TV STB Datacom Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) & 2015/863/EU (RoHS 3) compliant. 2. See AP3512E Typical Applications Circuit Input Voltage =12V C IN R EN 10F*2 100k C SS 0.1F 1 8 BS SS C C BS P Optional 10nF 2 7 IN EN C R C Output Voltage=3.3V 4.7H C L AP3512E 3 6 3.3nF 10k SW COMP 4 5 GND FB R2 C OUT 10k 22F*2 R1 26.1k Pin Descriptions Pin Number Pin Name Function Bootstrap pin. A bootstrap capacitor is connected between the BS pin and SW pin. The 1 BS voltage across the bootstrap capacitor drives the internal high-side NMOS switch. Supply input pin. A capacitor should be connected between the IN pin and GND pin to keep 2 IN the DC input voltage constant. 3 SW Power switch output pin. This pin is connected to the inductor and bootstrap capacitor. 4 GND Ground pin Feedback pin. This pin is connected to an external resistor divider to program the system output voltage. When the FB pin voltage exceeds 1.1V, the over voltage protection is 5 FB triggered. When the FB pin voltage is below 0.3V, the oscillator frequency is lowered to realize short circuit protection. Compensation pin. This pin is the output of the transconductance error amplifier and the input to the current comparator. This pin is used to compensate the control loop. Connect a 6 COMP series RC network from this pin to GND pin. In some cases, an additional capacitor from this pin to GND pin is required. Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on 7 EN the regulator, drive it low to turn off. Pull up with 100k resistor for automatic startup. Soft-start control input pin. SS controls the soft start period. Connect a capacitor from SS to 8 SS GND to set the soft-start period. A 0.1F capacitor sets the soft-start period to 15ms. To disable the soft-start feature, leave SS unconnected. EP Exposed pad. It should be connected to GND in PCB layout. 2 of 14 February 2020 AP3512E Diodes Incorporated www.diodes.com Document number: DS38502 Rev. 4 - 3