NXP Semiconductors BYM358X,127

Overview

BYM358X,127 from NXP Semiconductors (formerly Philips Semiconductors) is a dual-function fast high-voltage damper-modulator diode in a single SOT186A package, integrating a 1500 V damper diode and a 600 V modulator diode with isolated mounting tab. It delivers VF ≤ 1.6 V (damper, IF = 6.5 A), trr ≤ 170 ns (damper), trr ≤ 60 ns (modulator), and 2500 V RMS isolation voltage, designed for horizontal deflection circuits in PC monitors operating from 32 kHz to 120 kHz.

For engineers reviewing the BYM358X,127 datasheet, BYM358X,127 pinout, BYM358X,127 application, or BYM358X,127 equivalent, key selection criteria include peak reverse voltage separation (1500 V vs. 600 V), soft-recovery trr performance per function, thermal resistance to heatsink (Rth j-hs ≤ 5.5 K/W), and isolated tab compliance for high-voltage safety in CRT monitor power stages.

Technical Context

The BYM358X,127 integrates two electrically independent diodes-damper and modulator-on a common isolated heatsink tab, enabling simultaneous operation in flyback and modulation paths of horizontal deflection systems. Its soft recovery characteristic minimizes EMI during switching transitions, while the 2500 V RMS isolation ensures safe mounting to grounded metal chassis without additional insulation.

Each diode is optimized for distinct waveform demands: the damper handles high-voltage, low-duty-cycle flyback energy clamping (VRSM = 1500 V, IFSM = 66 A), while the modulator supports higher-frequency, higher-current switching (IF(peak) = 7 A, trr ≤ 60 ns, Qs ≤ 70 nC) in the resonant tank circuit.

Key Specifications

Pinout & Package

SOT186A plastic envelope with electrically isolated seating plane and tinned leads (except pin 3). Mounting tab is internally connected to case and electrically isolated from all three terminals.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar damper-modulator diode applications.

Compared with BYM358X,127, BYM359X,127 offers extended damper voltage headroom but same footprint and thermal behavior, while BYW29E,127 sacrifices integration and isolation for lower unit cost - making BYM358X,127 optimal for space-constrained, safety-critical CRT deflection designs.

Availability

BYM358X,127 is available at Aetrix Electronics and suitable for PC monitor manufacturing, industrial CRT display power supplies, and legacy broadcast video equipment requiring stable component supply and long-term obsolescence management.

Supply support for BYM358X,127 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

NXP Semiconductors is a global semiconductor leader specializing in high-reliability analog, power, and interface solutions for automotive, industrial, and consumer markets.

The BYM358X,127 belongs to NXP's legacy high-voltage rectifier family, engineered specifically for CRT horizontal deflection systems demanding integrated damper-modulator functionality, thermal resilience, and electrical isolation.

FAQ

What is the primary circuit role of the BYM358X,127 in CRT monitor designs?

The BYM358X,127 serves as a combined damper and modulator diode in horizontal deflection circuits. Its damper section clamps flyback voltage spikes from the line output transformer, while its modulator section enables resonant switching in the deflection yoke tank circuit. This dual functionality replaces two discrete diodes and simplifies layout in PC monitor power stages operating from 32 kHz to 120 kHz.

Does the BYM358X,127 require insulating hardware when mounted to a metal heatsink?

No, the BYM358X,127 does not require insulating hardware. Its SOT186A package features an electrically isolated seating plane rated for 2500 V RMS isolation between all three terminals and the mounting tab. This allows direct bolt-down to grounded metal chassis or heatsinks without mica washers or silicone pads - a critical safety and assembly advantage in CRT monitor production.

What are the maximum reverse recovery times for each diode function in the BYM358X,127?

The BYM358X,127 specifies trr ≤ 170 ns for the damper diode (measured at IF = 1 A, VR ≥ 30 V, -dIF/dt = 50 A/µs) and trr ≤ 60 ns for the modulator diode (measured at IF = 1 A, VR ≥ 30 V, -dIF/dt = 100 A/µs). These values are guaranteed maximums at Tj = 25 °C and reflect the device's ultrafast soft-recovery design optimized for horizontal deflection timing precision.

Can the BYM358X,127 be used in modern LCD or LED display power supplies?

The BYM358X,127 is not intended for modern LCD or LED display power supplies. It is specifically engineered for CRT horizontal deflection systems requiring dual damper-modulator functionality, 32–120 kHz operation, and high-voltage flyback clamping. Contemporary switch-mode power supplies use different topologies (e.g., LLC, QR flyback) and do not rely on this specialized dual-diode architecture.

What is the thermal resistance from junction to heatsink for the BYM358X,127 modulator section?

The thermal resistance from junction to heatsink (Rth j-hs) for the modulator section of the BYM358X,127 is ≤ 5.5 K/W when mounted with thermal compound to a properly sized heatsink. This value enables reliable operation at up to 14.1 A RMS forward current (IF(RMS)) under sinusoidal conditions with α = 1.57, supporting sustained performance in high-duty-cycle deflection applications.