Diodes Incorporated AP3987CTS7-13

Overview

AP3987CTS7-13 from Diodes Incorporated is a primary-side regulated (PSR) AC/DC power switcher integrating a 650V/2A MOSFET and PFM controller for flyback SMPS in battery chargers and adapters. It delivers <10mW no-load input power, supports optocoupler-free constant voltage (2.556V FB threshold) and constant current regulation, and includes built-in 0.35V cable drop compensation and valley-on switching for efficiency and EMI reduction.

For engineers reviewing the AP3987CTS7-13 datasheet, AP3987CTS7-13 pinout, AP3987CTS7-13 application, or AP3987CTS7-13 equivalent, key selection considerations include its SO-7 package, 650V drain-source breakdown, 4Ω R_DS(ON), 5–30μA standby current, and compatibility with APR3415CT synchronous rectifiers in low-power offline converters.

Technical Context

The AP3987CTS7-13 implements primary-side regulation using auxiliary winding feedback to eliminate optocouplers and loop compensation components. Its PFM control operates in discontinuous conduction mode (DCM), with three-segment peak current sensing (V_{CS_H} = 600mV, V_{CS_L} = 250mV) to maintain switching frequency above 20kHz across load range and avoid audible noise.

Valley-on switching triggers at t_VAL-ON = 27μs, reducing turn-on losses and enabling inherent frequency dithering for improved conducted EMI. Internal protections include auto-recovery OVP/SCP, fast-recovery TSP, and dual OTP (internal + external pin), with dedicated VOTP shutdown threshold of 0.52V and hysteresis of +40°C.

Key Specifications

Pinout & Package

AP3987CTS7-13 is housed in a 7-pin SOIC (SO-7) package with gull-wing leads, optimized for high-voltage isolation and thermal dissipation in compact offline SMPS designs. The exposed pad is not electrically connected; thermal path relies on PCB copper area (θ_JA = 92°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar primary-side regulated flyback controller applications.

Compared with AP3987CTS7-13, the AP3190T offers lower standby power and improved EMC, while the MP6004DJ provides higher current drive at the cost of larger footprint-making AP3987CTS7-13 optimal for cost-sensitive ≤15W adapters where SO-7 size and <10mW no-load are critical.

Availability

AP3987CTS7-13 is available at Aetrix Electronics and suitable for USB-C wall adapters, smartphone chargers, shaver power supplies, and IoT auxiliary PSUs requiring stable component supply and legacy design support.

Supply support for AP3987CTS7-13 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Diodes Incorporated is a global manufacturer of discrete semiconductors and ICs, specializing in power management, signal integrity, and protection solutions for consumer, industrial, and automotive markets.

The AP3987CTS7-13 belongs to Diodes' AC/DC PSR controller product line, engineered specifically for cost-sensitive, compact offline SMPS in portable electronics where optocoupler elimination and ultra-low standby power are mandatory.

FAQ

What is the maximum continuous output power supported by AP3987CTS7-13?

The AP3987CTS7-13 supports up to 15W continuous output power in standard flyback configurations with 650V MOSFET and 4Ω R_DS(ON). At 230VAC input and 5V/2A output, thermal limits and efficiency constraints define this ceiling-designs exceeding 12W require careful PCB copper area (≥1 in²) and airflow management per θ_JA = 92°C/W rating.

How does the 0.35V cable compensation function in practice?

The 0.35V cable compensation is added internally to the CV reference, effectively raising the target output voltage by 0.35V at the IC's feedback point. This offsets typical 0.3–0.4V IR drop across 1m USB-C cables, ensuring 5.00V ±0.05V is delivered at the device port instead of at the charger's output capacitor.

Can AP3987CTS7-13 operate without an external synchronous rectifier?

Yes-it can drive a Schottky diode in standard flyback mode. However, using APR3415CT or AP4341 improves efficiency by 3–5% and reduces output undershoot during load transients. The IC's dynamic response and valley-on timing are optimized for synchronous rectifier coordination, not standalone diode operation.

Is AP3987CTS7-13 qualified for automotive applications?

No-AP3987CTS7-13 is not AEC-Q100 qualified and lacks automotive-grade screening, PPAP documentation, or IATF 16949 manufacturing certification. Diodes explicitly states it is intended for consumer and industrial power supplies; automotive designs require contacting Diodes for qualified alternatives like the AP3987Q series.