STMicroelectronics STM806SM6E

Overview

STM806SM6E from STMicroelectronics is an industrial-grade 3 V microprocessor supervisory IC with integrated battery switchover, active-low push-pull RST output, manual reset (MR) input, and power-fail comparator (PFI/PFO). It guarantees reset assertion down to VCC = 1.0 V, delivers 200 ms typical reset timeout (trec), and draws only 40 µA typical supply current. It is used in embedded systems requiring reliable power monitoring and non-volatile SRAM backup during main supply interruption.

For engineers reviewing the STM806SM6E datasheet, STM806SM6E pinout, STM806SM6E application, or STM806SM6E equivalent, key selection criteria include guaranteed RST assertion at low VCC, battery switchover behavior, MR debounced timing, PFI threshold accuracy, and SO8 package compatibility for space-constrained PCB layouts.

Technical Context

The STM806 operates as a self-contained voltage supervisor with dual-supply monitoring: VCC is compared against a precision 2.63 V reset threshold (VRST) with 100 mV hysteresis, while PFI monitors external rail decay relative to a 1.25 V reference. Its logic diagram (Figure 2) confirms absence of watchdog timer - distinguishing it from STM690/802/804/805 variants.

Reset assertion is triggered by three independent conditions: VCC falling below VRST, MR pulled low, or PFI dropping below VPFI (or VCC falling below VSW = 2.4 V). The RST output is push-pull, active-low, and remains asserted for ≥200 ms after any trigger event clears - ensuring robust MCU reset hold time across temperature (–40 °C to +85 °C).

Key Specifications

Pinout & Package

STM806SM6E is housed in an 8-pin SO8 (Small Outline Integrated Circuit) package per JEDEC MS-012, with 1.27 mm pitch, body size 4.9 × 3.9 mm, and 1.75 mm max height. Pin 1 is marked with a dot or bevelled corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisory applications.

Compared with MAX809SEUR+T and TPS3808G125DBVR, STM806SM6E uniquely integrates battery switchover, PFI/PFO, and MR in SO8 - making it irreplaceable in cost-sensitive industrial SRAM backup applications where board area and feature consolidation matter.

Availability

STM806SM6E is available at Aetrix Electronics and suitable for industrial PLC controllers, smart electricity meters, factory HMI terminals, and medical infusion pump controllers requiring stable component supply across long product lifecycles.

Supply support for STM806SM6E 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, designing and manufacturing analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The STM690/704/806 family targets cost-sensitive industrial systems needing robust, integrated power supervision - emphasizing low quiescent current, guaranteed reset behavior, and SRAM backup without external components.

FAQ

Can STM806SM6E drive a 10 kΩ pull-up on RST?

Yes. The RST output is push-pull with 12 mA sink/source capability (per datasheet Figure 28–29), easily driving standard CMOS reset inputs. At VCC = 3.3 V, VOL ≤ 0.4 V with 1.2 mA load - well within TTL/CMOS logic thresholds. No external buffer is required.

What happens to VOUT when VCC = 0 V and VBAT = 3.0 V?

VOUT connects to VBAT through an internal ~100 Ω P-channel MOSFET switch, delivering regulated backup power to external LPSRAM. Output voltage drops ≤150 mV under 10 mA load (per Figure 27), supporting typical SRAM standby currents (<1 µA) for years on a CR2032.

Is MR input compatible with 5 V logic levels?

No. MR is designed for 3 V operation: absolute maximum rating is VCC + 0.3 V. Driving MR with 5 V risks latch-up or damage. For mixed-voltage systems, use a level-shifter or resistive divider to limit MR voltage to ≤3.6 V when VCC = 3.3 V.

Does STM806SM6E require external capacitors for stability?

No external timing or bypass capacitors are required. The 200 ms trec is fully internal; VCC and VBAT pins need only standard 0.1 µF ceramic decoupling (per Figure 10). PFI filtering is optional - a 0.1 µF cap to GND improves noise immunity in EMI-heavy environments.