TS831-4IZT - 4.5V Micropower Voltage Supervisor, Active-Low Reset, TO-92 | STMicroelectronics
MPN: TS831-4IZT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.05 | $1.05 |
| 10 | $0.92 | $9.20 |
| 100 | $0.74 | $74.00 |
| 500 | $0.61 | $305.00 |
| 1,000 | $0.52 | $520.00 |
TS831-4IZT Overview
A voltage supervisor is a specialized power management IC that monitors a system supply rail and asserts a reset signal whenever the rail voltage drops below a predefined safe operating threshold. Supervisors sit within the broader hierarchy of reset and power-good circuits, voltage detectors, and watchdog timers in PMIC (Power Management IC) families. Unlike a voltage regulator that actively controls the rail, a supervisor only observes and reports - allowing an MCU or ASIC to enter a deterministic safe state when VCC sags or collapses during brownout, inrush, or power sequencing events.
Key specifications of the TS831-4IZT include the 4.5V (TS831-4 series) factory threshold, 1.5 uA typical supply current, an open-drain RESET output (active-low) that requires an external pull-up resistor, and a 20 us typical comparator response time with 10 mV overdrive. The internal reference achieves 1.5% voltage accuracy across the -40C to +85C industrial temperature range, while the open-drain structure permits wired-OR reset logic across multiple rails or supervisors.
Architecturally, the TS831 combines a high-stability bandgap reference with a precision comparator stage whose threshold is defined by on-chip, thermally-matched resistor dividers. This monolithic approach eliminates drift introduced by external divider components and guarantees that all TS831-4IZT units assert reset at the same VCC level. The open-drain output allows the user to pull up to any voltage up to 5.5V regardless of VCC, simplifying mixed-voltage reset signaling in designs where logic and MCU rails differ.
Typical applications for the TS831-4IZT span 5V-tolerant microcontroller supervisor circuits (8051, MSP430, AVR, low-end Cortex-M0/M0+ devices), battery-powered equipment requiring ultra-low standby drain, embedded systems that need a deterministic reset during power-up and brownout, and industrial controls where a guaranteed reset signal improves safety and reliability. The micropower consumption also makes it well-suited for remote sensor nodes and energy-harvesting designs.
When designing with this part, ensure the external pull-up resistor on the RESET pin is sized to meet the downstream logic's leakage and rise-time requirements without violating the part's open-drain sink current rating. A 100 kohm pull-up to VCC is typical for low-speed reset networks; faster MCU reset inputs often benefit from a 10 kohm pull-up. Place the TS831 as close as possible to the supply it monitors, and add a 100 nF decoupling capacitor adjacent to VCC for noise immunity on noisy industrial buses.
This page consolidates distributor pricing, factory cross-reference alternatives, and practical design guidance not typically reproduced in the manufacturer datasheet - giving engineers a single decision-ready reference for selecting and sourcing the TS831-4IZT.
Drop-in alternatives for TS831-4IZT — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
TS831-4IZ
✅ Drop-In📋 Reference alternative (not in catalog)
TS831-4IDT
✅ Drop-In📋 Reference alternative (not in catalog)
DS1811R-5+
✅ Drop-In📋 Reference alternative (not in catalog)
MCP100T-450I/TO
✅ Drop-In📋 Reference alternative (not in catalog)
MC33064P-5
✅ Drop-In📋 Reference alternative (not in catalog)
TS831-4IZT Specifications
| Manufacturer | STMicroelectronics |
| Product Type | Micropower voltage supervisor |
| Threshold Voltage | 4.50 V (TS831-4 variant) |
| Reset Output Type | Active-Low, Open-Drain |
| Number of Supervisors / Channels | 1 |
| Supply Voltage (VCC) | 1 V to 5.5 V |
| Supply Current (Quiescent) | 1.5 uA (typical) |
| Comparator Response Time | 20 us (typical, with 10 mV overdrive) |
| Operating Temperature Range | -40C to +85C (industrial) |
| Mounting Type | Through-Hole |
| Package | TO-92 (3-pin, IZT tape/reel ammo) |
| RoHS Compliance | Compliant |
| MSL Level | Not Applicable (through-hole) |
TS831-4IZT Pin Configuration
| Pin 1 | VCC — Supply voltage input (1V to 5.5V); monitored rail |
| Pin 2 | GND — Ground reference |
| Pin 3 | RESET (active-low, open-drain) — Open-drain reset output; asserts low when VCC falls below 4.50V; requires external pull-up |
Typical Applications
TS831-4IZT is suitable for 6 applications: 5V Microcontroller Brownout Reset, Battery-Powered IoT Sensor Node, Industrial Control / PLC Logic Supervisor, Automotive 5V Subsystem Reset (non-safety), Test & Measurement Handheld Instrument, Set-Top Box / Consumer Embedded Reset.
5V Microcontroller Brownout Reset
The TS831-4IZT is purpose-built for monitoring a 5V rail that powers 8051, MSP430, AVR, and low-end Cortex-M0/M0+ MCUs. Placed between the 5V rail and the MCU's NRST pin with an external 10 kohm pull-up, the supervisor asserts reset whenever VCC sags below 4.50V - well within the 5% tolerance window before the regulator itself loses regulation. The 1.5 uA quiescent current adds negligible drain to standby budgets, and the 20 us response time guarantees reset assertion before any MCU internal POR releases. Designers benefit from factory-trimmed accuracy that eliminates external dividers and the associated drift.
Recommended
Battery-Powered IoT Sensor Node
Energy-harvesting and battery-backed IoT nodes need to enter deterministic sleep states during brownout to prevent flash corruption. The TS831-4IZT's 1.5 uA drain preserves coin-cell and harvested energy budgets, while its open-drain output can be wire-ORed with the MCU's internal POR for defense in depth. In a typical implementation, the supervisor sits across the 3.0V (TS831-3) or 5V (TS831-4) rail, pulling the MCU's reset low whenever the rail collapses below threshold - critical for solar/battery nodes that experience daily deep discharge cycles. Compared with conventional supervisors drawing 30 to 60 uA, the TS831 family extends battery life by an order of magnitude.
Recommended
Industrial Control / PLC Logic Supervisor
Programmable logic controllers, motor drive front-ends, and process control modules must assert a deterministic reset during brownout to prevent dangerous uncontrolled outputs on industrial 24V buses (after step-down to 5V). The TS831-4IZT's 4.50V threshold is calibrated for the 5V system rail of typical 24V->5V industrial converters, and its -40C to +85C industrial temperature rating handles factory floor environments. A 100 nF bypass capacitor on VCC prevents false resets from relay and motor switching transients. The open-drain RESET pin is suitable for safe wired-OR aggregation across multiple PLC logic rails.
Recommended
Automotive 5V Subsystem Reset (non-safety)
Body electronics, instrument clusters, and 12V->5V regulated accessories benefit from the TS831-4 family's micropower draw (1.5 uA) and small TO-92 footprint. While the TS831-4IZT is not itself AEC-Q100 qualified, the TS831-4IDT variant (automotive screening) in the same TO-92 package and pinout drops into the same PCB land pattern for non-safety body applications. Compared with typical automotive supervisors that draw 100 to 500 uA, the TS831-4 family's micropower drain helps meet quiescent draw budgets on CAN/LIN body modules that sleep at sub-mA currents.
Recommended
Test & Measurement Handheld Instrument
Battery-powered multimeters, oscilloscope probes, and field calibration tools benefit from the TS831-4IZT's ability to hold the MCU in reset during battery swap, USB unplug, or inadvertent cable disconnect events. The 1.5 uA drain preserves battery life during long field deployments, while the 4.50V threshold ensures the MCU does not write to non-volatile memory with a marginal rail. The TO-92 through-hole package is mechanically robust for handheld use and survives accidental drops better than SOT-23-3 SMD alternatives. Paired with an MCU watchdog timer, the system achieves defense in depth against code runaway.
Recommended
Set-Top Box / Consumer Embedded Reset
Set-top boxes, smart-home hubs, and consumer appliances often run from a regulated 5V internal rail with a 3.3V or 1.8V MCU core. The TS831-4IZT supervises the 5V rail while the open-drain RESET output is pulled up to the 3.3V core logic rail, enabling mixed-voltage signalling without level shifters. The micropower 1.5 uA standby drain helps meet ENERGY STAR and EU standby regulations for consumer electronics. Compared with SOT-23-3 supervisors that need reflow soldering, the through-hole TO-92 supports wave-solder manufacturing used in high-volume consumer electronics.
Recommended
Recommended Products Summary
Engineering reference data for TS831-4IZT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TS831-4IZ | TS831-4IDT | DS1811R-5+ | MCP100T-450I/TO | MC33064P-5 |
|---|---|---|---|---|---|---|
| Package | TO-92-3 (IZT ammo) | TO-92-3 (IZ ammo) | TO-92-3 (IDT tape-reel) | TO-92-3 | TO-92-3 | TO-92-3 |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | Maxim | Microchip | onsemi |
| Threshold Voltage | 4.50 V | 4.50 V | 4.50 V | 4.50 V | 4.50 V | 4.50 V |
| Reset Polarity | Active-Low | Active-Low | Active-Low | Active-Low | Active-Low | Active-Low |
| Output Stage | Open-Drain | Open-Drain | Open-Drain | Open-Drain | Push-Pull | Open-Drain (active-low)/Push-Pull (active-high variant) |
| Quiescent Current (typ) | 1.5 uA | 1.5 uA | 1.5 uA | ~35 uA | ~25 uA | ~350 uA |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +125C (automotive grade) | -40C to +85C | -40C to +85C (industrial) | -40C to +85C |
| AEC-Q100 Automotive | No (use TS831-4IDT) | No | Yes | No | No | No |
| Approx. Unit Price (qty-1) | $1.05 | $0.85 | $1.20 | $1.65 | $0.95 | $0.70 |
Key Differentiators
- Lowest quiescent current among TO-92 4.5V supervisors (vs DS1811R-5+ (Maxim))
- Lower quiescent current than Microchip MCP100T-450I/TO (vs MCP100T-450I/TO (Microchip))
- Lower drain and fixed factory threshold (no external dividers) (vs MC33064P-5 (onsemi))
Design Notes
Decouple VCC with a 100 nF ceramic capacitor placed within 5 mm of pin 1. On industrial 24V->5V converter rails, a 10 uF bulk capacitor on the 5V rail combined with the local 100 nF bypass suppresses switching noise transients that could otherwise cause false reset assertions. The TS831-4IZT draws only 1.5 uA quiescent, so it does not load the regulator measurably - but always sum supervisor Iq when calculating standby battery drain on energy-harvesting designs.
Place the TS831-4IZT as close as possible to the MCU it monitors - long PCB traces between the supervisor and the reset pin create inductive paths that delay RESET deassertion on power-up. Keep the pull-up resistor (typically 10 kohm to 100 kohm) adjacent to the supervisor's RESET pin, not at the MCU end of the trace, to maintain a sharp rising edge. The TO-92 mechanical drawing shows the device is intended to be inserted into the PCB with pin 1 (VCC) nearest the regulator output, allowing short straight-line routing.
Do not connect the open-drain RESET pin directly to VCC without a pull-up resistor - the absence of a pull-up will leave the reset node floating and the MCU may boot spuriously during brownout. Also avoid connecting multiple TS831 outputs directly in parallel (wired-OR is only safe when all outputs are open-drain AND the pull-up is sized for the worst-case sink current sum). Do not exceed 5.5V on VCC or on the pull-up rail - the TS831-4IZT is not rated above 5.5V and may be damaged.
The TS831-4IZT typically dissipates only VCC x 1.5 uA = 7.5 uW at 5V supply, so thermal management is not a concern even at +85C ambient. However, when using the TO-92 in a sealed enclosure or near a heatsink, route the through-hole leads with short stubs and provide at least 2 mm of clearance to high-temperature components. Estimated: at +85C ambient and worst-case Iq of 5 uA, junction rise is negligible (<1 C) given the TO-92 thermal resistance of approximately 200 C/W to still air.
Compliance Information
RoHS and REACH compliance per ST eStore product page. AEC-Q100 not applicable for standard IZT grade; for AEC-Q100 use TS831-4IDT automotive variant. Lead-free finish confirmed. Halogen-free status not stated in data; recommend confirming with ST factory declaration if required.
