Overview
The LM3881MMX/NOPB, produced by Texas Instruments, is a Simple Power Sequencer with adjustable timing. This device is designed to control the power-up and power-down sequences of multiple power supplies, including both switching and linear regulators. It is particularly useful in avoiding latch conditions or large inrush currents that can affect system reliability. The LM3881 is available in a VSSOP-8 package, offering a tiny footprint and low quiescent current of 80 µA, making it suitable for a variety of applications where precise power sequencing is required.
Key Specifications
| Parameter | Description | Value |
|---|---|---|
| Input Voltage Range | VCC | 2.7 V to 5.5 V |
| Quiescent Current | IQ | 80 µA |
| Package Type | VSSOP | 8-pin |
| Body Size | Nominal | 3.00 mm x 3.00 mm |
| Output Flags | Open-Drain Outputs | FLAG1, FLAG2, FLAG3 |
| Enable Pin | Precision Enable | EN |
| Output Logic Invert | INV Pin | Active High or Active Low |
| Timer Adjust | TADJ Pin | External Capacitor Controlled |
Key Features
- Easiest Method to Sequence Rails: The LM3881 provides a straightforward way to control the power-up and power-down sequences of multiple power supplies.
- Power-Up and Power-Down Control: It can manage both switching and linear regulators, ensuring a sequential start-up and shut-down to avoid latch conditions or large inrush currents.
- Tiny Footprint: Available in a VSSOP-8 package, making it ideal for space-constrained designs.
- Low Quiescent Current: Operates with a low quiescent current of 80 µA, reducing power consumption.
- Output Invert Feature: The output flags can be set to active high or active low using the INV pin.
- Timing Controlled by External Capacitor: The time delays for the output flags are controlled by an external capacitor connected to the TADJ pin.
Applications
- Security Cameras: Ensures proper power sequencing to prevent system failures.
- Servers: Used in server systems to manage multiple power supplies efficiently.
- Networking Elements: Suitable for networking equipment that requires precise power sequencing.
- FPGA Sequencing: Helps in sequencing power supplies for Field-Programmable Gate Arrays (FPGAs).
- Microprocessor and Microcontroller Sequencing: Ideal for managing power supplies in microprocessor and microcontroller-based systems.
- Multiple Supply Sequencing: Can handle the sequencing of multiple power supplies in various electronic systems.
Q & A
- What is the primary function of the LM3881?
The LM3881 is a Simple Power Sequencer designed to control the power-up and power-down sequences of multiple power supplies.
- What is the input voltage range for the LM3881?
The input voltage range for the LM3881 is 2.7 V to 5.5 V.
- What is the quiescent current of the LM3881?
The quiescent current of the LM3881 is 80 µA.
- How are the output flags controlled in the LM3881?
The output flags (FLAG1, FLAG2, FLAG3) are controlled by the enable pin (EN) and can be set to active high or active low using the INV pin.
- How is the timing for the output flags adjusted in the LM3881?
The timing for the output flags is adjusted using an external capacitor connected to the TADJ pin.
- What package type is the LM3881 available in?
The LM3881 is available in a VSSOP-8 package.
- What are some common applications of the LM3881?
The LM3881 is commonly used in security cameras, servers, networking elements, FPGA sequencing, and microprocessor/microcontroller sequencing.
- How does the LM3881 prevent latch conditions during power-up?
The LM3881 prevents latch conditions by staggering the start-up sequence of the power supplies, ensuring that each supply starts up after a defined delay.
- What is the purpose of the INV pin in the LM3881?
The INV pin allows the user to invert the logic mode of the output flags, making them either active high or active low.
- How should the pullup resistors be connected for the flag outputs in the LM3881?
Pullup resistors should be connected between the flag output pins and a positive input supply, usually VCC, and placed as close as possible to the Simple Power Sequencer and the flag supply.
