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STMicroelectronics L9777A13TR
- Part No.:
- L9777A13TR
- Manufacturer:
- STMicroelectronics
- Package:
- 12-LSOP (0.154", 3.90mm Width) Exposed Pad
- Datasheet:
-
L9777A13TR.pdf
- Description:
- IC REG LIN POS ADJ 600MA PWRSSO
- Quantity:
- Payment:
- Shipping:
Inventory:3,848
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Product details
Overview
L9777A13TR 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 supervision, watchdog, adjustable undervoltage threshold, and automotive-grade thermal protection (TJ = −40 °C to +150 °C). It operates from 5.6 V to 31 V input and is designed for microprocessor power supply in engine control units, body controllers, and ADAS domain controllers.
For engineers reviewing the L9777A13TR datasheet, L9777A13TR pinout, L9777A13TR application, or L9777A13TR equivalent, key selection considerations include its dual-regulator architecture (VCC primary + VDD tracking), programmable reset delay via external capacitor on D pin, VDD_EN–controlled VDD enable/disable, RADJ-based VCC undervoltage threshold adjustment, and option-C–specific VDD_LOW monitoring function.
Technical Context
The L9777A13TR implements a two-stage regulation architecture: a main 5 V LDO (VCC) with 200 mA capability and ±2% accuracy over full temperature and input range, plus a secondary tracking regulator (VDD) enabled via VDD_EN and rated for 50 mA with 1.5 V max dropout. Its reset logic features dual-stage filtering-first on VCC-to-NMI (spike-depth–dependent delay), then NMI-to-RESET (fixed delay set by TIMING pin capacitor).
Watchdog functionality uses an internal oscillator charging/discharging external capacitor CD to monitor WD input frequency; missing edges within 48 oscillation periods trigger NMI assertion. The RADJ pin enables precise VCC undervoltage threshold setting (0.7×VCC to 0.96×VCC) via resistor divider, while VDD_LOW (Option C) provides dedicated 300 mV–below-VCC undervoltage detection on the RESET pin with spike-dependent filter timing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage (VCC) | 5.0 V ±2% - stable reference for MCU core/logic supply across automotive transients and temperature extremes. |
| Max Output Current (VCC) | 200 mA - sufficient for mid-tier automotive MCUs and peripheral ICs without external boost stages. |
| Input Voltage Range | 5.6 V to 31 V - supports 12 V and 24 V battery systems including cold-crank (5.6 V) and load-dump (31 V) conditions. |
| Quiescent Current | 110 μA typ @ IOUT = 0 - enables always-on operation in low-power vehicle modules without excessive battery drain. |
| VDD Tracking Regulator | Switchable 5 V output (50 mA, 1.5 V max dropout) - provides auxiliary rail synchronized to VCC, disabled when VDD_EN = low. |
| Reset Threshold Accuracy | Adjustable 0.7×VCC to 0.96×VCC via RADJ - allows match to specific MCU VDD brownout requirements using external resistors. |
| Operating Junction Temp | −40 °C to +150 °C - qualified for under-hood automotive placement with integrated overtemperature shutdown. |
Pinout & Package
Supplied in PowerSSO-12 package with exposed die pad for enhanced thermal dissipation in high-ambient automotive environments.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (RESET/VDD_LOW) | Output (Option C) | VDD_LOW open-collector output asserted low when VDD falls >300 mV below VCC; replaces double-reset function in Option C. |
| 2 (NMI) | Output | Non-maskable interrupt output triggered by VCC undervoltage or watchdog timeout; drives MCU NMI input directly. |
| 3 (D) | Input | External capacitor sets NMI filter time, watchdog oscillator period, and RESET power-up delay (TRD = 0.62 ms + 7.874 s/F × CD). |
| 4 (VDD_EN) | Input | Active-high enable for VDD regulator; pulled down internally (10 μA) in Option C - must be driven high to activate VDD. |
| 5 (WD) | Input | Watchdog input monitoring MCU-generated pulses; missing edge within 48 oscillator cycles triggers NMI assertion. |
| 6 (WD_EN) | Input | Active-high watchdog enable; pulled down internally (10 μA) in Option C - must be driven high to activate watchdog. |
| 7 (VI) | Input | Main input supply (5.6–31 V); requires ≥100 nF bypass capacitor to GND for stability and transient immunity. |
| 8 (TIMING) | Input (Option C: NC) | In Option C, unused - must be left floating or shorted to GND; in Options A/B, sets NMI-to-RESET delay via external capacitor. |
| 9 (VCC) | Output | Main regulated 5 V output (200 mA); requires ≥220 nF ceramic capacitor to GND for loop stability and noise suppression. |
| 10 (VDD) | Output | Tracking 5 V output (50 mA); requires 100 nF ceramic capacitor; disabled if VDD_EN = low or VCC < undervoltage threshold. |
| 11 (GND) | Power Return | Primary ground reference for all regulators, comparators, and drivers; connects to exposed die pad for thermal conduction. |
| 12 (RADJ) | Input | Adjusts VCC undervoltage threshold (0.7–0.96×VCC) via resistor divider; tied to GND for fixed 0.94×VCC internal threshold. |
Key Features
| Feature | Design Value |
|---|---|
| VDD tracking regulator with VDD_EN control | Enables selective powering of auxiliary circuits (e.g., CAN transceivers, sensors) only when main VCC is stable. |
| Spike-depth–dependent reset filter (TRR) | Increases immunity to fast transients: deeper VCC dips yield longer NMI assertion delays, preventing false resets. |
| Adjustable VCC undervoltage threshold via RADJ | Permits precise alignment with MCU-specific brownout levels (e.g., 4.2 V for 5 V-tolerant cores) without redesign. |
| VDD_LOW monitoring (Option C) | Reassigns RESET pin to detect VDD faults independently - critical for systems where VDD powers safety-critical peripherals. |
| Integrated watchdog with programmable timeout | Uses single external capacitor (CD) to set both watchdog window and NMI delay, reducing BOM count and layout complexity. |
Applications
| Engine Control Unit (ECU) | Body Control Module (BCM) |
|---|---|
|
Use Scenario: Powering 32-bit ARM-based MCU, CAN FD transceiver, and analog sensor interface in under-hood ECU subject to load dump and cold-crank. IC Role / Device Role / Timing Role: Primary 5 V regulator (VCC) supplies MCU core; VDD powers CAN transceiver; NMI feeds MCU NMI pin for immediate fault response. Use Value: 150 °C junction rating and 31 V input tolerance ensure uninterrupted operation during extreme thermal and electrical stress. |
Use Scenario: Supplying microcontroller, LIN transceiver, door lock actuators, and ambient light sensor in dashboard-mounted BCM. IC Role / Device Role / Timing Role: VCC powers MCU and digital logic; VDD_EN–gated VDD drives LIN bus; RADJ-adjusted reset threshold matches MCU's 4.3 V brownout level. Use Value: Adjustable reset delay (via D pin cap) prevents spurious resets during ignition transients while maintaining fast response to sustained undervoltage. |
| ADAS Domain Controller | Electric Power Steering (EPS) |
|
Use Scenario: Providing clean, supervised 5 V rails to vision processor, radar SoC, and safety monitor in centralized ADAS controller. IC Role / Device Role / Timing Role: Dual-regulator architecture isolates processor core (VCC) from high-noise peripherals (VDD); watchdog monitors vision processor health. Use Value: Independent VDD_LOW monitoring (Option C) detects VDD failure before it affects safety-critical actuator interfaces. |
Use Scenario: Powering torque-sensing MCU, motor gate drivers, and position encoder in EPS module requiring ASIL-B compliance. IC Role / Device Role / Timing Role: NMI output triggers immediate MCU safe state entry; VDD_EN enables VDD only after VCC stabilization to prevent premature peripheral activation. Use Value: Overtemperature shutdown and short-circuit proof design meet functional safety requirements for steering-assist systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar automotive LDO + supervision applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLE4275G | Single 5 V LDO (150 mA), no VDD tracking, no watchdog, fixed 4.5 V reset threshold. | Lacks programmable reset, VDD supervision, and watchdog - suitable only for basic MCU supply without system-level monitoring. | Select when cost sensitivity outweighs need for multi-rail supervision and diagnostic coverage. |
| MC33FS4500 | System basis chip with 5 V/250 mA LDO, integrated CAN/LIN, configurable reset, but no VDD tracking or RADJ adjustment. | Includes communication PHYs but lacks VDD_LOW monitoring and fine-grained VCC threshold tuning via RADJ. | Prefer when CAN/LIN physical layer integration is required and VDD supervision is handled externally. |
Compared with TLE4275G and MC33FS4500, the L9777A13TR uniquely combines VCC+VDD dual regulation, RADJ-adjustable reset threshold, and Option-C–specific VDD_LOW monitoring - enabling tighter control over multi-rail automotive subsystems without adding discrete supervisors.
Availability
L9777A13TR is available at Aetrix Electronics and suitable for engine control units, body control modules, and ADAS domain controllers requiring stable component supply across extended temperature and voltage ranges.
Supply support for L9777A13TR 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 delivery and system-level supervision in harsh vehicle environments.
FAQ
What is the function of the RADJ pin on the L9777A13TR?
The RADJ pin sets the VCC undervoltage detection threshold via an external resistor divider. When connected to a voltage divider between VCC and GND, it adjusts the reset point from 0.7×VCC to 0.96×VCC (typical). If tied to GND, the device uses its internal 0.94×VCC threshold. This enables precise matching to MCU brownout specifications without firmware changes.
How does the VDD_EN pin control the VDD output?
VDD_EN is an active-high enable input. In Option C (L9777A13TR), VDD_EN must be driven high (≥2.0 V) to activate the VDD tracking regulator; if left floating or pulled low, VDD remains disabled. VDD also shuts down automatically if VCC falls below its undervoltage threshold, ensuring safe sequencing during power-up and brownout events.
Can the L9777A13TR be used in non-automotive applications?
Yes - while qualified for automotive use (AEC-Q100 Grade 0), its wide input range (5.6–31 V), −40 °C to +150 °C operation, and integrated supervision make it suitable for industrial motor drives, railway control systems, and off-grid power equipment where reliability under voltage transients and thermal stress is critical.
What distinguishes Option C (L9777A13TR) from Options A and B?
Option C removes the double-reset function (NMI + RESET), repurposing the RESET pin as VDD_LOW - a dedicated open-collector output that asserts low when VDD drops >300 mV below VCC. TIMING pin becomes no-connect, and VDD_EN/WD_EN inputs are internally pulled down (10 μA), reducing quiescent current to 100 μA typ. This simplifies designs needing only one reset signal with VDD supervision.
L9777A13TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 12-LSOP (0.154", 3.90mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Configuration:
- Positive
- Output Type:
- Adjustable
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 31V
- Voltage - Output (Min/Fixed):
- 4.9V
- Voltage - Output (Max):
- 5.1V
- Voltage Dropout (Max):
- 0.4V @ 200mA
- Current - Output:
- 600mA
- Current - Quiescent (Iq):
- 220 µA
- Current - Supply (Max):
- -
- PSRR:
- 55dB (100Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature, Short Circuit
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- PowerSSO-12
L9777A13TR FAQ
1.How can I place an order for L9777A13TR through Aetrix?
Please submit a Request for Quotation (RFQ) for L9777A13TR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for L9777A13TR reliable?
The price and inventory of L9777A13TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L9777A13TR is usually 5 days.
3.What payment methods are accepted for L9777A13TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L9777A13TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L9777A13TR?
L9777A13TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L9777A13TR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for L9777A13TR?
For technical support, including L9777A13TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L9777A13TR requirements.
6.How does Aetrix verify that L9777A13TR is sourced from the original manufacturer or authorized distributors?
All L9777A13TR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that L9777A13TR meets industry standards.
7.What is the process for return or replacement of L9777A13TR?
All L9777A13TR units undergo pre-shipment inspection (PSI). If there is an issue with L9777A13TR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The L9777A13TR part is unused and in its original packaging.
Return procedure for L9777A13TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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