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STMicroelectronics TSM1121ID
- Part No.:
- TSM1121ID
- Manufacturer:
- STMicroelectronics
- Category:
- Supervisors
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
TSM1121ID.pdf
- Description:
- IC SUPERVISOR 3 CHANNEL 14SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,567
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Product details
Overview
TSM1121ID from STMicroelectronics is a triple-rail housekeeping IC for PC SMPS, providing overvoltage (3.3V/5V/12V) and undervoltage protection without external components, 2.5V precision reference, power-good signaling with adjustable delay, and remote-controlled latch reset. It operates from 4.5–24V supply and supports 0–85°C ambient.
For engineers reviewing the TSM1121ID datasheet, TSM1121ID pinout, TSM1121ID application, or TSM1121ID equivalent, key selection considerations include its integrated OVP/UVP thresholds (e.g., Vov12 = 14.2V typ), UV blanking during power-up (Tuv = 100–500ms), fault latching behavior, and SO-14 package compatibility with legacy ATX designs.
Technical Context
The TSM1121ID integrates three independent voltage comparators per rail (3.3V/5V/12V) for both overvoltage and undervoltage detection, with internal thresholds referenced to a 2.5V bandgap source. Its logic combines OVP/UVP outputs via OR gates feeding a fault latch with fixed 100µs OVP delay and no additional UVP delay post-blanking.
It features three externally adjustable timing circuits: Tuv (UV blanking at startup), Tpg (PG assertion delay), and Trem (remote reset pulse width), each set by capacitor values on dedicated pins. The REM input enables active-high motherboard-controlled system reset, while PI allows external PG enable/disable control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Vov12 | 14.2V typical - triggers OVP on 12V rail before damage to downstream logic |
| Vuv5 | 4.0V typical - asserts UVP when 5V rail drops below PCI bus tolerance |
| Vref | 2.50V ±0.04V - stable reference for all internal comparators and external circuitry |
| Tpg | 100–500ms adjustable - ensures PG only asserts after all rails stabilize |
| Tfault | 100µs fixed - fast OVP response critical for short-circuit protection in SMPS |
| Icc | 5mA typical - low quiescent current enables use in standby power domains |
| ESD | 2kV HBM - sufficient for handling in standard PC assembly environments |
Pinout & Package
Package: SO-14 (Plastic Micropackage), 8.55–8.75 mm × 5.8–6.2 mm body, 1.27 mm pitch, gull-wing leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VS33) | Analog Input | Sense node for 3.3V rail OVP/UVP detection; accepts voltages > Vcc within absolute max rating |
| 2 (VS5) | Analog Input | Sense node for 5V rail OVP/UVP detection; shares same internal comparator architecture as VS33 |
| 3 (VS12) | Analog Input | Sense node for 12V rail OVP/UVP detection; threshold set internally at 14.2V typ |
| 4 (EP) | Analog Input | Extra protection input for negative rail OVP (e.g., –12V) using external resistor divider |
| 5 (PI) | Digital Input | Power-good enable/disable control; active-low logic with 1.28V threshold |
| 6 (TUV) | Timing Capacitor | Connects to capacitor setting UV blanking duration (100–500ms) during Vcc ramp-up |
| 7 (GND) | Power Reference | 0V reference for all analog and digital functions; must be low-impedance connection |
| 8 (VREF) | Voltage Output | 2.5V ±0.04V precision reference output; max 20mA load, not to be shorted |
| 9 (REM) | Digital Input | Active-high remote reset control; 0.8V threshold, enables motherboard-initiated latch clear |
| 10 (TREM) | Timing Capacitor | Connects to capacitor setting REM pulse width (40–60ms) for reliable latch reset |
| 11 (TPG) | Timing Capacitor | Connects to capacitor setting PG assertion delay (100–500ms) post-rail stabilization |
| 12 (PG) | Open-Collector Output | Active-high power-good signal; 0.4V saturation at 15mA, requires external pull-up |
| 13 (FAULT) | Open-Collector Output | Active-high fault indicator; latched until REM pulse clears; 1V saturation at 1mA |
| 14 (VCC) | Power Supply | 4.5–24V DC input; powers all internal circuits including reference and comparators |
Key Features
| Feature | Design Value |
|---|---|
| Triple-rail OVP/UVP | No external resistors needed for 3.3V/5V/12V thresholds - reduces BOM count and layout area |
| Adjustable UV blanking | TUV pin accepts 2.2µF cap to suppress false UVP trips during slow Vcc ramp-up |
| Programmable PG delay | TPG pin supports 100–500ms delay to ensure all rails settle before asserting PG to CPU |
| Remote-controlled latch reset | REM + TREM pins allow motherboard to initiate full system reset without power cycle |
| Integrated 2.5V reference | VREF pin delivers ±0.04V accuracy over temperature - usable for external ADC or DAC biasing |
Applications
| ATX Power Supply Housekeeping | Industrial Triple-Rail Monitoring |
|---|---|
|
Use Scenario: Real-time monitoring of 3.3V, 5V, and 12V outputs in desktop PC ATX power supplies during startup, steady-state, and shutdown. IC Role / Device Role / Timing Role: Central housekeeping controller that sequences PG assertion, detects OVP/UVP faults, and signals motherboard via REM/PG/FAULT lines. Use Value: Eliminates discrete comparator networks and timing RC networks - reduces component count by ≥12 parts per rail. |
Use Scenario: Supervision of multi-output industrial DC-DC converters powering PLC I/O modules, where rail sequencing and fault isolation are critical. IC Role / Device Role / Timing Role: Fault coordinator that latches on first OVP/UVP event and holds all outputs off until remote reset is applied. Use Value: Prevents cascading failures by disabling all rails simultaneously upon single-rail fault - improves system MTBF. |
| Embedded System Power Sequencing | Legacy Server PSU Management |
|
Use Scenario: Power-up coordination for FPGA-based embedded systems requiring strict 3.3V-before-12V sequencing and brownout immunity. IC Role / Device Role / Timing Role: Voltage supervisor with programmable TUV blanking and TPG delay to enforce safe ramp order and hold-off windows. Use Value: Enables deterministic boot without custom FPGA logic or external sequencer ICs - cuts firmware bring-up time. |
Use Scenario: Retrofit upgrade of aging server PSUs to meet modern safety standards for OVP response time and latch reliability. IC Role / Device Role / Timing Role: Drop-in replacement for obsolete discrete supervision circuits, retaining existing SO-14 footprint and timing caps. Use Value: Achieves <100µs OVP response (vs. >500µs in legacy designs) - meets IEC 62368-1 transient overvoltage requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-rail voltage supervision applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCD90120A | 12-channel digital PMBus supervisor with programmable thresholds and sequencing; requires external MCU configuration | Supports dynamic reconfiguration and telemetry logging; not pin-compatible | Choose for new designs needing adaptive rail management and fault diagnostics |
| TPS386000 | Dual-rail supervisor (not triple); separate 3.3V/5V channels only; no EP pin or REM control | Lacks 12V supervision and remote reset - requires supplemental circuitry for full ATX coverage | Choose only if redesigning for dual-rail systems or adding discrete 12V monitoring |
Compared with UCD90120A and TPS386000, the TSM1121ID provides fully integrated triple-rail protection in a fixed-function SO-14 package with zero configuration overhead, making it optimal for cost-sensitive, high-volume ATX and industrial PSU replacements where digital flexibility is unnecessary.
Availability
TSM1121ID is available at Aetrix Electronics and suitable for ATX power supplies, industrial multi-output DC-DC converters, and embedded system housekeeping requiring stable component supply and long-lifecycle support.
Supply support for TSM1121ID 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, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.
The TSM1121ID belongs to ST's legacy power management housekeeping IC family, engineered specifically for cost-effective, high-reliability supervision of PC and industrial SMPS triple-output architectures.
FAQ
What is the function of the EP pin on TSM1121ID?
The EP (Extra Protection) pin is an analog input designed for overvoltage protection of negative rails such as –12V or –5V. It uses an internal 1.28V threshold and requires an external resistor divider to scale the negative voltage into the detectable range. Unlike VS33/VS5/VS12, EP does not support undervoltage detection and is intended solely for supplemental OVP coverage beyond the three main positive rails.
Can TSM1121ID operate with a 3.3V-only supply?
No. The TSM1121ID requires a minimum VCC of 4.5V and operates up to 24V. It cannot be powered directly from a 3.3V rail. In systems with only 3.3V available, an auxiliary 5V or higher supply - such as standby voltage (5VSB) in ATX designs - must be used to power VCC. This is confirmed by the Absolute Maximum Ratings table specifying VCC = 1–25V and Operating Conditions listing VCC = 4.5–24V.
How does the TUV pin affect system startup behavior?
The TUV pin connects to a capacitor that sets the under-voltage blanking window during VCC ramp-up. With a 2.2µF capacitor, TUV provides 100–500ms of blanking, preventing premature UVP assertion while the 3.3V/5V/12V rails are still rising. This avoids false fault latching at startup and ensures the housekeeping IC waits for stable conditions before enabling PG and monitoring.
Is TSM1121ID still in active production?
The TSM1121ID is marked "Obsolete Product(s)" in the official STMicroelectronics datasheet revision A (May 2003). However, Aetrix Electronics maintains verified inventory with full traceability and offers lifecycle support including last-time buy planning, cross-reference guidance, and engineering consultation for legacy design continuity and repair programs.
TSM1121ID Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Multi-Voltage Supervisor
- Number of Voltages Monitored:
- 3
- Voltage - Threshold:
- 4V, 6.1V, 14.2V
- Output:
- -
- Reset:
- -
- Reset Timeout:
- 100ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SO
TSM1121ID FAQ
1.How can I place an order for TSM1121ID through Aetrix?
Please submit a Request for Quotation (RFQ) for TSM1121ID 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 TSM1121ID reliable?
The price and inventory of TSM1121ID are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TSM1121ID is usually 5 days.
3.What payment methods are accepted for TSM1121ID?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TSM1121ID transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TSM1121ID?
TSM1121ID orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TSM1121ID 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 TSM1121ID?
For technical support, including TSM1121ID datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TSM1121ID requirements.
6.How does Aetrix verify that TSM1121ID is sourced from the original manufacturer or authorized distributors?
All TSM1121ID 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 TSM1121ID meets industry standards.
7.What is the process for return or replacement of TSM1121ID?
All TSM1121ID units undergo pre-shipment inspection (PSI). If there is an issue with TSM1121ID, 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 TSM1121ID part is unused and in its original packaging.
Return procedure for TSM1121ID:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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