STMicroelectronics STM708RDS6E

Overview

STM708RDS6E from STMicroelectronics is a 3 V precision voltage supervisor IC with active-high and active-low reset outputs, 2.59 V to 2.70 V reset threshold (R-grade), 200 ms reset timeout, and integrated power-fail comparator (PFI/PFO). It operates from –40 °C to +85 °C and draws only 40 µA typical supply current. Used in industrial controllers and embedded systems requiring reliable power-on reset and early brownout warning.

For engineers reviewing the STM708RDS6E datasheet, STM708RDS6E pinout, STM708RDS6E application, or STM708RDS6E equivalent, key selection factors include dual RST/RST output polarity, guaranteed reset assertion down to VCC = 1.0 V, watchdog timer absence (distinguishing it from STM706 variants), and TSSOP8-3x3 mm package compatibility with space-constrained PCB layouts.

Technical Context

The STM708RDS6E implements a precision bandgap-based voltage reference and comparator to monitor VCC against a fixed 2.59–2.70 V reset threshold. It asserts both RST (active high) and RST (active low) simultaneously during out-of-tolerance conditions, with reset timeout (trec) internally generated at 200 ms (typ.). Unlike STM706-series parts, it omits watchdog circuitry - confirmed by logic diagram Figure 2 and Table 1 - simplifying supervision for systems without software watchdog requirements.

Its power-fail comparator uses an independent 1.25 V internal reference (VPFI) to detect falling input voltage on PFI, driving push-pull PFO low when VPFI is exceeded. The MR input features an internal 40 kΩ pull-up and supports direct switch-to-ground connection without external debounce, enabling robust manual reset functionality in noisy industrial environments.

Key Specifications

Pinout & Package

STM708RDS6E is housed in an 8-pin TSSOP package (3 mm × 3 mm body, DS suffix), RoHS-compliant and optimized for automated assembly and thermal performance in dense layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage supervision applications.

Compared with STM708RDS6E, the DS6F variant offers mechanical compatibility with through-hole or legacy SO8 designs, while the TPS3808G12DBVR trades supervision richness for extreme current efficiency - making STM708RDS6E optimal where compact dual-output supervision with early power-fail detection is mandatory.

Availability

STM708RDS6E is available at Aetrix Electronics and suitable for industrial controllers, smart energy meters, medical sensor hubs, and factory automation I/O modules requiring stable component supply across extended product lifecycles.

Supply support for STM708RDS6E 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 sensing solutions for industrial, automotive, and consumer markets.

The STM70x supervisor family targets cost-sensitive, space-constrained embedded systems needing reliable, single-chip power monitoring - emphasizing precision threshold accuracy, guaranteed low-VCC reset, and minimal external components.

FAQ

What is the function of the NC pin on STM708RDS6E?

Pin 8 is designated NC (No Connect) and is internally unbonded. It must remain unconnected - no routing, soldering, or grounding is permitted. This pin exists solely for mechanical symmetry in the TSSOP8 package and has no electrical function. Connecting it may compromise device reliability or violate ESD protection design.

Can STM708RDS6E be used with a 5 V supply?

Yes - STM708RDS6E supports VCC from 1.0 V to 5.5 V. Its 2.59–2.70 V reset threshold remains valid across this range, and all outputs (RST, RST, PFO) are push-pull rated for full rail-to-rail swing. At 5 V, supply current rises to ~55 µA (max), well within specification, and reset timing remains stable per Figure 15.

How does the power-fail comparator interact with the reset outputs?

The PFI/PFO circuit operates independently of the VCC reset comparator. When PFI falls below 1.25 V, PFO goes low but does not directly assert RST or RST. To generate a reset on power-fail, PFO must be externally connected to MR. This decoupling allows flexible system-level response - e.g., initiating graceful shutdown before forcing hard reset.

Is there a watchdog timer in STM708RDS6E?

No - STM708RDS6E excludes watchdog functionality. This is confirmed by its device summary (Table 1), logic diagram (Figure 2), and absence of WDI/WDO pins. The "8" in STM708 denotes the dual-RST architecture without watchdog, distinguishing it from STM706T/S/R/P variants which include WDI/WDO. Systems requiring watchdog must select STM706-series parts.