STMicroelectronics STCS1PHR

Overview

STCS1PHR from STMicroelectronics is a BiCMOS constant current LED driver in PowerSO-8 package, delivering up to 1.5 A output with ±10% current accuracy, <0.5 V dropout at full load, and integrated PWM dimming and open-drain LED disconnection diagnostic. It replaces discrete solutions in 5–24 V low-voltage lighting systems including appliance status indicators and architectural accent lighting.

For engineers reviewing the STCS1PHR datasheet, STCS1PHR pinout, STCS1PHR application, or STCS1PHR equivalent, key selection criteria include its 4.5–40 V input range, 100 mV feedback reference for precise current setting via external resistor, shutdown and diagnostic pin behavior, thermal performance on two-layer PCBs, and compatibility with standard LED string configurations requiring stable current regulation under varying supply conditions.

Technical Context

The STCS1PHR integrates a high-voltage preregulator (up to 45 V), precision 100 mV bandgap-referenced current-sense amplifier, and N-channel MOSFET driver in a single BiCMOS die. Its control loop maintains constant current by regulating DRAIN voltage to hold FB at 100 mV ±10 mV across temperature and input voltage variation.

Diagnostic functionality monitors DRAIN-to-GND voltage: DISC asserts low when V_DRAIN falls below 75 mV (LED open) and releases above 110 mV; shutdown is controlled independently via EN pin, reducing quiescent current to <1 µA. PWM dimming operates up to 50 kHz with ≤4 µs rise/fall delay, enabling synchronized multi-channel LED control.

Key Specifications

Pinout & Package

STCS1PHR uses the PowerSO-8 package: thermally enhanced surface-mount housing with exposed die attach pad, 5.0 mm × 6.2 mm footprint, 1.7 mm height, and 1.27 mm lead pitch. Designed for high-power density LED driver applications requiring efficient heat transfer to PCB copper planes.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar constant-current LED driver applications.

Compared with AL8862SP-13 and LM3407MMX/NOPB, STCS1PHR uniquely combines linear simplicity, 40 V input support, integrated diagnostic, and PowerSO-8 thermal performance-making it optimal for cost-sensitive, space-constrained, and reliability-critical 5–24 V LED systems where EMI and component count are primary concerns.

Availability

STCS1PHR is available at Aetrix Electronics and suitable for smart appliance status lighting, industrial panel indicator modules, and architectural accent lighting requiring stable component supply, long-term manufacturability, and RoHS-compliant packaging.

Supply support for STCS1PHR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power ICs, sensors, and analog devices for industrial, automotive, and consumer markets.

The STCS1 product line targets replacement of discrete LED driver circuits in low-voltage applications (5–24 V), emphasizing integration, precision, and reliability for lighting subsystems where board space, thermal management, and fault visibility are critical.

FAQ

What is the minimum input voltage required for STCS1PHR to regulate 1.5 A LED current?

The absolute minimum input voltage is determined by the sum of LED forward voltage plus dropout voltage. At 1.5 A, typical dropout is 0.58 V; with three 3.6 V white LEDs, minimum V_IN = 10.8 V + 0.58 V = 11.38 V. The device specifies 4.5 V minimum V_CC, but regulation requires sufficient headroom - confirmed by Figure 5 showing stable I_DRAIN only above ~11.5 V at full load.

Can STCS1PHR drive multiple parallel LED strings?

No - STCS1PHR is a single-channel constant-current sink. Driving parallel strings causes current imbalance due to V_F mismatch, leading to thermal runaway in the lowest-V_F string. For multi-string applications, one STCS1PHR per string is required, with individual R_FB resistors. Shared PWM/EN signals are supported for synchronized dimming and shutdown.

How does the DISC pin behave during PWM dimming?

DISC remains fully functional during PWM operation: it continuously monitors V_DRAIN while EN = high. If V_DRAIN drops below 75 mV (indicating open LED) during any PWM ON or OFF period, DISC pulls low within microseconds and stays low until V_DRAIN rises above 110 mV. This allows real-time fault detection regardless of dimming state.

Is reverse polarity protection built into STCS1PHR?

No - STCS1PHR has no internal reverse-voltage protection. The datasheet explicitly states (Section 8.1) that a series diode (e.g., BAT46) must be placed between VIN and VCC to prevent damage from reversed supply connections. Without external protection, applying negative voltage to VCC can exceed absolute maximum ratings and permanently damage the IC.