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Microchip Technology MIC74YQS-TR
- Part No.:
- MIC74YQS-TR
- Manufacturer:
- Microchip Technology
- Category:
- I/O Expanders
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
MIC74YQS-TR.pdf
- Description:
- IC XPNDR 100KHZ I2C SMBUS 16QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,117
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Product details
Overview
MIC74YQS-TR from Microchip Technology is an SMBus/I²C-compatible 8-bit serial-to-parallel I/O expander with integrated fan speed control logic, operating from 2.7V to 3.6V, featuring 5V-tolerant I/O pins, 2 µA typical quiescent current, and programmable push-pull or open-drain outputs - used in PC system management and microcontroller I/O expansion.
For engineers reviewing the MIC74YQS-TR datasheet, MIC74YQS-TR pinout, MIC74YQS-TR application, or MIC74YQS-TR equivalent, key selection considerations include its QSOP-16 package, interrupt-on-change capability via /ALERT, fan mode configuration (P4–P7 as /SHDN and /FS[2:0]), register-based I/O direction/output-type control, and support for up to eight devices per bus.
Technical Context
The MIC74YQS-TR implements a fully programmable SMBus client interface with seven internal registers (DEV_CFG, DIR, OUT_CFG, STATUS, INT_MASK, DATA, FAN_SPEED) for configuring I/O direction, output drive type, interrupt masking, and fan control. Its internal state machine handles fan startup sequencing without host intervention.
It supports two operational modes: standard I/O expansion (P0–P7 as general-purpose bits) and fan control mode (P4–P7 repurposed as /SHDN and /FS[2:0], disabling interrupts on those pins). Addressing uses three hardware-selectable pins (A0–A2), enabling up to eight devices on one bus with unique 7-bit addresses (0x20–0x27).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2.7V to 3.6V - compatible with 3.3V system rails; not 5V-supplied |
| I/O Voltage Tolerance | 5V-tolerant inputs - allows interfacing with legacy 5V logic without level shifters |
| Quiescent Current | 2 µA typical - enables low-power always-on monitoring in portable/desktop systems |
| Output Drive | 10 mA sink per I/O (IOL) - sufficient to directly drive LEDs or small logic loads |
| Interrupt Latency | <4 µs from input change to /ALERT assertion - enables responsive host event handling |
| Fan Startup Interval | 1 sec typical (tSTART) - ensures reliable fan spin-up before settling to programmed speed |
| Operating Temperature | –40°C to +85°C - qualified for industrial and commercial embedded environments |
Pinout & Package
Package: 16-pin QSOP (QS), 3.9 mm × 4.9 mm footprint, 1.0 mm max height - optimized for space-constrained PCB layouts in desktop and portable systems.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A2 | Address Input | Set LSBs of 7-bit SMBus address (0x20–0x27); sampled once at power-on |
| P0–P3 | General-Purpose I/O | Individually configurable as input/output, push-pull/open-drain; support interrupt-on-change |
| P4 (/SHDN) | Fan Control Output | In fan mode: active-low shutdown signal for external fan driver or regulator |
| P5–P7 (/FS0–/FS2) | Fan Speed Outputs | In fan mode: 3-bit encoded fan speed control (000 = off, 111 = fastest) |
| GND | Ground Reference | Common return for all analog/digital functions; must be low-impedance |
| VDD | Power Supply | 2.7V–3.6V supply; decoupling capacitor required near pin |
| /ALERT | Interrupt Output | Open-drain, active-low signal indicating pending input-change events; cleared by ARA or STATUS read |
| CLK | SMBus Clock Input | Host-provided clock (max 100 kHz); timing-critical for data setup/hold compliance |
| DATA | SMBus Data I/O | Open-drain bidirectional line; requires external pull-up resistor (typically 2.2–10 kΩ) |
Key Features
| Feature | Design Value |
|---|---|
| 8-bit programmable I/O | Each bit independently set as input/output with push-pull or open-drain drive - eliminates need for external buffer logic |
| Fan control logic | Integrated state machine manages /SHDN and /FS[2:0] timing including 1-second startup burst - removes host firmware overhead for fan ramp-up |
| Interrupt-on-change | Dedicated /ALERT output signals input transitions without polling - reduces host CPU load and bus traffic |
| Register-based configuration | Seven accessible registers (DEV_CFG, DIR, OUT_CFG, STATUS, etc.) enable full runtime reconfiguration - supports dynamic system adaptation |
| Multi-device bus support | Three address pins allow up to eight MIC74YQS-TR devices on one SMBus - scales I/O capacity to 64 bits without additional controllers |
Applications
| PC System Management | Microcontroller I/O Expansion |
|---|---|
Use Scenario: Monitoring thermal sensors, chassis intrusion switches, and power-good signals in desktop motherboards. IC Role / Device Role / Timing Role: Acts as SMBus slave providing parallel status inputs and LED control outputs; /ALERT notifies host of critical events asynchronously. Use Value: Reduces host polling frequency and frees MCU resources while maintaining real-time response to hardware faults. |
Use Scenario: Adding GPIOs to resource-constrained 8-bit MCUs in industrial controllers or smart peripherals. IC Role / Device Role / Timing Role: Serial-to-parallel bridge extending MCU's native I/O count; P0–P3 drive status LEDs, P4–P7 manage peripheral enable lines. Use Value: Enables compact design without sacrificing functionality - avoids larger MCU migration or discrete logic complexity. |
| Fan Speed Control | Distributed Sensing Node |
Use Scenario: Regulating cooling fans in network switches or NAS enclosures based on temperature sensor feedback. IC Role / Device Role / Timing Role: Fan controller generating /SHDN and /FS[2:0] signals; internal oscillator sequences startup burst and speed transitions. Use Value: Ensures reliable fan start-up at low speeds and eliminates need for external timing components or firmware timing loops. |
Use Scenario: Remote environmental monitoring using multiple digital sensors (e.g., door/window contacts, motion detectors) across a building. IC Role / Device Role / Timing Role: Local I/O concentrator aggregating binary sensor states; /ALERT alerts central controller only on state changes. Use Value: Minimizes bus bandwidth usage and host processing load in large-scale distributed systems with infrequent events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar I/O expansion applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| PCA9555DWR | 16-bit I/O, no built-in fan control logic, higher IDD (10 µA typ), same QSOP-24 package | Requires external firmware for fan sequencing; better suited for pure GPIO scaling | Select when >8 I/O bits are needed and fan control is handled externally |
| TCA6408APWR | 8-bit I/O, no fan mode, lower VDD range (1.65–5.5V), 1 µA IDD, TSSOP-16 package | Lacks /SHDN and /FS[2:0] outputs; supports wider voltage range but no integrated fan logic | Select for ultra-low-power 3.3V/5V mixed-voltage systems without fan requirements |
Compared with PCA9555DWR and TCA6408APWR, the MIC74YQS-TR uniquely integrates fan startup sequencing and dedicated /SHDN control in a compact QSOP-16, making it optimal for thermal management subsystems where minimizing host intervention and board area is critical.
Availability
MIC74YQS-TR is available at Aetrix Electronics and suitable for PC system management, microcontroller I/O expansion, and fan speed control applications requiring stable component supply and long-term industrial availability.
Supply support for MIC74YQS-TR 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
Microchip Technology is a leading provider of microcontrollers, analog components, and connectivity solutions, serving automotive, industrial, consumer, and communications markets with high-reliability silicon and development tools.
The MIC74 product line delivers SMBus/I²C-based I/O expansion with integrated system management features - designed specifically for PC platform controllers, embedded thermal management, and resource-constrained host interfaces.
FAQ
What is the primary function of the MIC74YQS-TR?
The MIC74YQS-TR is an 8-bit serial-to-parallel I/O expander with SMBus/I²C interface and integrated fan speed control logic. It provides programmable general-purpose I/O (P0–P7), interrupt-on-change capability via /ALERT, and dedicated fan outputs (/SHDN, /FS0–/FS2) - enabling both GPIO expansion and thermal management in a single QSOP-16 device.
Does the MIC74YQS-TR support 5V logic levels on its I/O pins?
Yes, the MIC74YQS-TR features 5V-tolerant I/O pins (P0–P7, A0–A2, /ALERT), meaning it accepts input voltages up to 5.5V regardless of VDD (2.7V–3.6V). This allows direct connection to 5V sensors, switches, or LEDs without external level-shifting circuitry - a key advantage in mixed-voltage system designs.
How does fan control work on the MIC74YQS-TR?
Fan control is activated by setting the FAN bit in the DEV_CFG register. When enabled, P4 becomes /SHDN (active-low shutdown), and P5–P7 become /FS0–/FS2 (3-bit fan speed encoding). The internal state machine automatically sequences startup (1-second high-speed burst) and interprets FAN_SPEED register values (000–111) to drive corresponding outputs - no host timing code required.
Can the MIC74YQS-TR generate interrupts for all eight I/O pins?
No - only P0–P3 support interrupt-on-change when configured as inputs and enabled via INT_MASK and DEV_CFG. In fan mode, P4–P7 are repurposed as /SHDN and /FS[2:0], and interrupts are disabled on those pins. The /ALERT output reflects pending interrupts from P0–P3 only, and is cleared by reading the STATUS register or responding to the Alert Response Address (ARA).
What package type is used for the MIC74YQS-TR?
The MIC74YQS-TR is supplied in a 16-pin QSOP (Quad Small Outline Package) with 0.635 mm pitch, measuring 3.9 mm × 4.9 mm and 1.0 mm maximum height. This ultra-small footprint supports high-density PCB layouts in space-constrained applications such as laptop docking stations, embedded controllers, and compact server modules.
MIC74YQS-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Number of I/O:
- 8
- Interface:
- I2C, SMBus
- Interrupt Output:
- Yes
- Features:
- Fan Speed Controller
- Output Type:
- Open Drain, Push-Pull
- Current - Output Source/Sink:
- 7mA, 10mA
- Clock Frequency:
- 100 kHz
- Voltage - Supply:
- 2.7V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QSOP
MIC74YQS-TR FAQ
1.How can I place an order for MIC74YQS-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for MIC74YQS-TR 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 MIC74YQS-TR reliable?
The price and inventory of MIC74YQS-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MIC74YQS-TR is usually 5 days.
3.What payment methods are accepted for MIC74YQS-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MIC74YQS-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MIC74YQS-TR?
MIC74YQS-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MIC74YQS-TR 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 MIC74YQS-TR?
For technical support, including MIC74YQS-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MIC74YQS-TR requirements.
6.How does Aetrix verify that MIC74YQS-TR is sourced from the original manufacturer or authorized distributors?
All MIC74YQS-TR 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 MIC74YQS-TR meets industry standards.
7.What is the process for return or replacement of MIC74YQS-TR?
All MIC74YQS-TR units undergo pre-shipment inspection (PSI). If there is an issue with MIC74YQS-TR, 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 MIC74YQS-TR part is unused and in its original packaging.
Return procedure for MIC74YQS-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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