STMicroelectronics L9777B13TR

Overview

L9777B13TR from STMicroelectronics is a monolithic low-dropout voltage regulator delivering up to 200 mA on VCC (5 V ±2%) and 50 mA on switchable VDD, with integrated NMI/RESET monitoring, adjustable undervoltage threshold, watchdog timer, and overtemperature/short-circuit protection - designed for automotive microprocessor power and supervision in harsh environments.

For engineers reviewing the L9777B13TR datasheet, L9777B13TR pinout, L9777B13TR application, or L9777B13TR equivalent, this device supports critical automotive subsystems requiring dual regulated outputs, programmable reset timing, fail-safe watchdog supervision, and operation across –40 °C to +150 °C junction temperature.

Technical Context

The L9777B13TR implements a primary 5 V LDO regulator (VCC) with 2% accuracy over 5.6–31 V input and –40 °C to +150 °C, plus a tracking VDD output enabled via VDD_EN pin. Its reset architecture features dual-stage filtering: NMI triggers on VCC undervoltage with depth-dependent delay (1 μs min at 2.5 V), while RESET follows NMI after a fixed external capacitor–set delay on TIMING pin.

Watchdog functionality monitors WD input frequency using an internal oscillator charging/discharging external capacitor CD; missing edges within 48 oscillation periods (≈2.976×10⁶·CD seconds) assert NMI. The RADJ pin enables external resistor-divider adjustment of VCC undervoltage threshold between 0.7×VCC and 0.96×VCC (typ.), with internal default at 0.94×VCC.

Key Specifications

Pinout & Package

Supplied in PowerSSO-12 package with exposed die pad for thermal dissipation; pin 11 is GND, pin 12 is RADJ, and the exposed pad must be soldered to PCB ground plane for optimal thermal performance and EMI control.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar automotive LDO + supervisor applications.

Compared with TLV70733PDPWR and MAX16126ATJ+T, the L9777B13TR uniquely integrates dual regulated outputs, programmable reset threshold, and watchdog with single-chip footprint and automotive-qualified ruggedness - eliminating design compromises between supervision fidelity and power integration.

Availability

L9777B13TR is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS domain controllers, and transmission control units requiring stable component supply across extended temperature and voltage ranges.

Supply support for L9777B13TR 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, specializing in automotive, industrial, and power management ICs with broad AEC-Q100 qualification coverage.

The L9777 belongs to ST's automotive power management portfolio, engineered specifically for robust microprocessor power and supervision in engine bay and chassis applications where reliability under voltage transients and thermal stress is non-negotiable.

FAQ

What is the maximum allowable input voltage for L9777B13TR?

The absolute maximum input voltage (VI) is 40 V, verified per ST's DocID13496 Rev 4 Table 3. This rating applies across all operating conditions and enables compatibility with 24 V commercial vehicle systems and ISO 7637-2 Pulse 5a load dump events. Operation above 31 V is permissible only for transient surges within specified duration limits.

How does the VDD_EN pin control the VDD output?

VDD_EN is a logic-level enable input: when pulled high (≥2.0 V), the VDD tracking regulator activates and delivers up to 50 mA; when low (≤0.8 V) or left floating, VDD is disabled and sinks negligible current. Internal 5 µA pull-up ensures default-on behavior in Option A, but L9777B13TR uses Option B with internal 10 µA pull-down - requiring explicit high-level drive for activation.

Can the reset threshold be set below 0.7×VCC using the RADJ pin?

No - the RADJ pin supports adjustment only between 0.7×VCC and 0.96×VCC (typical), as confirmed in Section 3.4 and Figure 11 of the datasheet. Attempting lower thresholds via external resistors violates the internal comparator design and may result in undefined reset behavior or failure to assert NMI at expected voltages.

Is the PowerSSO-12 package RoHS and AEC-Q100 qualified?

Yes - the L9777B13TR in PowerSSO-12 is qualified to AEC-Q100 Grade 0 (–40 °C to +150 °C) and complies with RoHS Directive 2011/65/EU, as documented in ST's official product change notices and qualification reports referenced in DocID13496 Rev 4. The exposed die pad enhances thermal performance critical for automotive under-hood use.