Monolithic Power Systems Inc. HF500GS-15-Z

Overview

HF500GS-15-Z from Monolithic Power Systems is a fixed-frequency, current-mode flyback regulator IC integrating a 700V/4.5Ω rugged MOSFET, built-in slope compensation, and full protection suite for offline AC/DC power supplies. It delivers up to 15W at 230Vac (open frame), supports frequency foldback down to 25kHz, burst mode for <300mW standby, and operates across 85–265Vac input. Used in auxiliary power rails for set-top boxes and home appliances.

For engineers reviewing the HF500GS-15-Z datasheet, HF500GS-15-Z pinout, HF500GS-15-Z application, or HF500GS-15-Z equivalent, key selection criteria include integrated 700V MOSFET ruggedness, timer-based OLP with programmable delay, over-power compensation independent of input voltage, and SOIC8-7B thermal performance (θJA = 85°C/W).

Technical Context

The HF500GS-15-Z implements fixed-frequency current-mode control with internal slope compensation (18–31 mV/μs) to prevent subharmonic oscillation in CCM operation above 50% duty cycle. Its high-voltage start-up current source draws from DRAIN until VCC reaches 12V, then switches to auxiliary winding supply.

Protection logic is tightly coordinated: B/O pin enables brown-in/out (0.9V/0.9V thresholds), input OVP (4.5V), and over-power compensation (0–270mV offset); TIMER pin integrates soft-start ramp (1V→1.75V), frequency jitter modulation (±6.5% amplitude, 3.7ms period), and latched OLP after 32ms fault detection.

Key Specifications

Pinout & Package

HF500GS-15-Z is housed in a SOIC8-7B package (standard 8-pin SOIC with exposed pad omitted; 1.27mm pitch, 5.0mm × 6.2mm body).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar flyback controller applications.

Compared with UCC28740DR and ICE5QSBG, HF500GS-15-Z uniquely combines 700V integration, input-voltage-independent over-power compensation, and coordinated B/O/TIMER protection - enabling simpler, more robust universal-input designs with lower system-level EMI filter cost.

Availability

HF500GS-15-Z is available at Aetrix Electronics and suitable for home appliance auxiliary power, set-top box standby supplies, and universal-input adapters requiring stable component supply across global manufacturing sites.

Supply support for HF500GS-15-Z 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

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, with design centers in the US, China, and Taiwan.

The HF500GS-15-Z belongs to MPS's HF500 family of highly integrated flyback controllers, engineered specifically for compact, low-BOM-count offline power supplies targeting consumer and industrial auxiliary rails.

FAQ

What is the maximum continuous output power achievable with HF500GS-15-Z in an open-frame design?

The HF500GS-15-Z delivers up to 15W continuous output power in an open-frame configuration at 230Vac ±15% and 50°C ambient temperature, limited by junction temperature (150°C) and SOIC8-7B thermal resistance (θJA = 85°C/W). At 85Vac, output is derated to 12W due to higher RMS current stress.

How does the over-power compensation feature maintain constant output power across varying input voltages?

Over-power compensation adds a voltage offset (0–270mV) to the current-sense threshold based on the B/O pin voltage, which scales linearly with input voltage. This dynamically adjusts the peak current limit so that POUT = VOUT × IOUT remains constant from 85Vac to 265Vac without external circuitry.

Can HF500GS-15-Z operate without an auxiliary winding for VCC supply?

Yes - the internal high-voltage current source (3.6mA typical) charges the VCC capacitor directly from the DRAIN pin during startup, eliminating the need for an auxiliary winding. Once regulation is established, the auxiliary winding takes over; if absent, the IC relies solely on the HV start-up source with appropriate VCC capacitance (≥22µF recommended).

What protection mechanisms trigger a latched shutdown versus auto-restart behavior?

Latched shutdown occurs only on VCC OVP (if VCC exceeds 27V for 60ms) or TIMER pin pull-down below 1V for 42μs. All other protections - thermal shutdown (150°C), SCP, OLP, and brownout - implement auto-restart with hysteresis to recover after fault removal without manual reset.

Is the SOIC8-7B package thermally enhanced compared to standard SOIC8?

No - the SOIC8-7B is a standard 8-pin SOIC package without an exposed thermal pad. Its θJA of 85°C/W is measured on a 4-layer JEDEC PCB (JESD51-7); thermal performance depends entirely on copper area under pins 4 (DRAIN) and 5 (SOURCE), which carry high-current paths and must be routed with ≥200mil² copper pour for 15W operation.

How is frequency jittering implemented and what is its practical EMI benefit?

Frequency jittering is generated by charging/discharging the TIMER capacitor with 10μA current sources between 2.8V and 3.2V, creating a 3.7ms modulation period. This spreads the 65kHz fundamental and harmonics across a ~8kHz bandwidth, reducing peak conducted EMI by 10–15dB and easing compliance with CISPR 22/32 Class B limits.

What is the minimum recommended TIMER capacitor value for reliable soft-start and OLP timing?

A 47nF capacitor on the TIMER pin is recommended to achieve the specified 32ms OLP timeout and controlled soft-start ramp (1V→1.75V). Values below 33nF risk premature OLP triggering during startup transients; values above 68nF extend soft-start duration excessively, risking VCC UVLO dropout under heavy load.