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Analog Devices Inc. LTC694CS8-3.3#TRPBF
- Part No.:
- LTC694CS8-3.3#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC694CS8-3.3#TRPBF.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,303
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Product details
Overview
LTC694CS8-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a 3.3V microprocessor supervisory circuit integrating power-on reset, battery-backed RAM power switching, RAM write protection, power-fail warning, and watchdog timing in an 8-pin SOIC package. It asserts RESET below 2.90V threshold, guarantees logic-low RESET down to VCC = 1V, delivers up to 50mA from VOUT via charge-pumped NMOS switch, and consumes only 0.6mW typical operating power - enabling robust system monitoring in battery-powered controllers and industrial embedded systems.
For engineers reviewing the LTC694CS8-3.3#TRPBF datasheet, LTC694CS8-3.3#TRPBF pinout, LTC694CS8-3.3#TRPBF application, or LTC694CS8-3.3#TRPBF equivalent, key selection criteria include guaranteed reset assertion at 1V VCC, 2.90V precision supply monitor, fast 30ns CE gating for RAM write protection, 1μA max battery-backup current, and SO-8 footprint compatibility with legacy LTC694/LTC695 designs.
Technical Context
The LTC694CS8-3.3#TRPBF implements dual comparator-based supervision: C1 monitors VCC against a 2.90V bandgap reference with 40mV hysteresis for glitch immunity, while C2 performs battery switchover by comparing VCC and VBATT with 70mV/50mV thresholds and 20mV hysteresis. Its internal charge-pumped NMOS switch (M1) supplies VOUT from VCC with 5Ω typical RDS(on), and a PMOS switch (M2) enables low-dropout battery backup delivering 250μA at <100mV dropout.
It integrates a programmable watchdog timer with two timeout modes (100ms/1.6s typical) selectable via OSC SEL, and a user-configurable power-fail detector (C3) comparing PFI to a 1.30V internal reference. The device supports external capacitor-based timing on OSC IN and includes dedicated CE IN/CE OUT pins for sub-50ns RAM chip-enable gating during brownout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.90V ±0.10V - ensures reliable μP reset before 3.3V rail collapse into invalid operating range |
| VCC Range for RESET Assertion | Down to 1V - maintains active-low reset state through deep brownout, preventing μP runaway |
| VOUT Supply Current | 50mA max - sufficient to power CMOS RAM and small logic during primary supply loss |
| Battery Backup Current | 1μA max - minimizes auxiliary battery drain during extended standby |
| CE Gating Propagation Delay | 30ns typical - enables real-time RAM write blocking when VCC drops below threshold |
| Power Consumption | 0.6mW typical at 3.3V - reduces thermal load and extends battery life in portable systems |
| Package | 8-Lead Plastic SO (S8) - industry-standard footprint compatible with automated assembly |
Pinout & Package
Package: 8-Lead Plastic SO (S8), 180°C/W junction-to-ambient thermal resistance, operating temperature range 0°C to 70°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: VBATT | Battery Input | Connects auxiliary battery (1.5–2.75V); enables PMOS switchover to VOUT when VCC falls below VBATT −50mV |
| 2: VCC | Main Supply Input | 3.3V system rail input; monitored by C1 for reset generation and by C2 for battery switchover |
| 3: VOUT | Backed-Up Memory Output | Delivers regulated power to RAM; sourced from VCC via NMOS switch (5Ω) or VBATT via PMOS switch (125Ω) |
| 4: GND | Ground Reference | Common return for all analog and digital functions; requires local 0.1μF bypass |
| 5: PFI | Power-Fail Input | Non-inverting input to C3 comparator; triggers PFO low when voltage falls below 1.30V threshold |
| 6: GND | Ground Reference | Second ground pin for noise isolation; must be tied to same plane as Pin 4 |
| 7: PFO | Power-Fail Output | Open-drain output signaling early power degradation; used to interrupt μP for controlled shutdown |
| 8: RESET | Active-Low Reset Output | Drives μP reset pin low during brownout or watchdog timeout; guaranteed functional down to VCC = 1V |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed Reset at 1V VCC | Enables fail-safe shutdown even during severe brownout, preventing undefined μP behavior |
| Charge-Pumped NMOS VOUT Switch | Achieves 5Ω RDS(on) and <0.1V dropout at 50mA - eliminates substrate injection and battery overcharge risk |
| Integrated RAM Write Protection | CE IN/CE OUT path blocks writes within 30ns of VCC drop - preserves data integrity without external logic |
| Adjustable Power-Fail Warning | PFI/PFO pair allows configurable early-warning threshold (e.g., trip at 3.1V before 2.9V reset) via external divider |
| Low-Power Battery Backup Mode | 1μA max supply current with VCC = 0V - extends lithium or coin-cell life for years in standby |
Applications
| Industrial Control PLCs | Medical Portable Monitors |
|---|---|
Use Scenario: Maintaining volatile configuration memory and real-time clock during AC mains interruption or battery swap. IC Role / Device Role / Timing Role: Supervisory IC providing VOUT power switchover, RAM write lock, and 200ms reset pulse to hold controller in safe state. Use Value: Prevents memory corruption and unsafe actuator movement during transient power loss. | Use Scenario: Preserving patient parameter history and calibration data in handheld ECG or SpO₂ devices during battery replacement. IC Role / Device Role / Timing Role: Battery-backed RAM power manager and brownout detector ensuring data retention down to 1V VCC. Use Value: Eliminates need for supercapacitors or FRAM, reducing BOM cost and board area. |
| Automotive Infotainment Head Units | Smart Utility Meters |
Use Scenario: Safeguarding firmware update buffers and security keys during vehicle ignition cycling or 12V battery fluctuations. IC Role / Device Role / Timing Role: Dual-threshold supervisor asserting RESET on VCC dip and generating PFO interrupt for graceful firmware save. Use Value: Avoids bricking due to interrupted OTA updates caused by unstable supply sequencing. | Use Scenario: Retaining metering logs and tariff settings during grid outage or tamper-induced power cut. IC Role / Device Role / Timing Role: Low-quiescent-current supervisor enabling >10-year coin-cell operation with guaranteed RAM retention. Use Value: Meets IEC 62056-21 long-term data integrity requirements without external backup capacitors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6326US31D3+T | Single 3.1V reset threshold; no battery switchover, no CE gating, no PFI/PFO | Suitable only for basic reset-only applications; lacks RAM power management and early warning capability | Select when only reset functionality is needed and board space is constrained |
| TPS3808G33DBVR | 3.3V reset threshold with 200ms fixed delay; no battery backup, no watchdog, no PFI interface | Provides precise reset timing but cannot support battery-backed memory or power-fail interrupt | Choose for cost-sensitive 3.3V systems requiring only reset assertion with tight voltage tolerance |
Compared with MAX6326US31D3+T and TPS3808G33DBVR, the LTC694CS8-3.3#TRPBF uniquely integrates battery switchover, RAM write protection, and programmable power-fail warning - making it the only option among the three capable of full-system supervision in battery-critical applications.
Availability
LTC694CS8-3.3#TRPBF is available at Aetrix Electronics and suitable for industrial control PLCs, medical portable monitors, automotive infotainment head units, and smart utility meters requiring stable component supply across extended production lifecycles.
Supply support for LTC694CS8-3.3#TRPBF 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
Analog Devices, Inc. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies.
The LTC694-3.3 product line was designed specifically for 3.3V microprocessor systems requiring integrated power monitoring, battery backup, and data integrity protection - targeting industrial, medical, and automotive applications where reliability under brownout is critical.
FAQ
What is the guaranteed minimum VCC level at which LTC694CS8-3.3#TRPBF maintains valid RESET assertion?
The LTC694CS8-3.3#TRPBF guarantees RESET remains logic low down to VCC = 1V with ISINK = 10μA. This is confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables, where RESET output voltage is specified at 4mV (max) under those conditions. This feature ensures the microprocessor stays held in reset during deep brownout events where other supervisors would release prematurely, preventing undefined execution states in the LTC694CS8-3.3#TRPBF-equipped system.
Does LTC694CS8-3.3#TRPBF support battery-backed RAM power switchover, and what are the voltage limits?
Yes, the LTC694CS8-3.3#TRPBF supports automatic battery switchover via its VBATT and VOUT pins. It connects VOUT to VBATT when VCC falls below VBATT −50mV, using a 125Ω PMOS switch optimized for low-dropout backup. VBATT operates from 1.5V to 2.75V, and the device draws only 1μA maximum in battery-backup mode. This capability is explicitly documented in the Battery Back-Up Switching section of the Electrical Characteristics table and the Battery Switchover Applications Information subsection for the LTC694CS8-3.3#TRPBF.
How does the CE IN/CE OUT function protect RAM writes during supply brownout?
The LTC694CS8-3.3#TRPBF uses CE IN as a chip-enable input and CE OUT as a buffered, fault-tolerant replica. When VCC is above 2.90V, CE OUT follows CE IN with 30ns typical propagation delay. When VCC drops below threshold or VBATT, CE OUT is forced high - disabling RAM writes regardless of CE IN state. This hardware-enforced write lock is detailed in Figure 5 and the Memory Protection Applications Information section, ensuring data integrity without software intervention in the LTC694CS8-3.3#TRPBF design.
Can LTC694CS8-3.3#TRPBF generate an early power-fail warning, and how is it configured?
Yes, the LTC694CS8-3.3#TRPBF provides early power-fail warning via its PFI/PFO pins. PFI accepts a user-defined voltage (e.g., from a resistor divider off VCC), and PFO asserts low when PFI falls below 1.30V. Hysteresis can be added using an external resistor from PFO to PFI, enabling adjustable upper/lower trip points. This is fully described in the Power-Fail Warning Applications Information section and verified in Figures 8–9 of the LTC694CS8-3.3#TRPBF datasheet.
What is the maximum continuous output current capability of VOUT on LTC694CS8-3.3#TRPBF?
The VOUT pin of the LTC694CS8-3.3#TRPBF delivers up to 50mA continuously when powered from VCC via its internal charge-pumped NMOS switch, with a typical on-resistance of 5Ω. This is specified in the "VOUT Output Voltage" row of the Electrical Characteristics table under IOUT = 50mA conditions. Short-circuit protection limits peak current to ~200mA, and thermal shutdown activates at ~155°C to protect the LTC694CS8-3.3#TRPBF during overload.
LTC694CS8-3.3#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.9V
- Output:
- Open Drain or Open Collector
- Reset:
- Active High/Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC694CS8-3.3#TRPBF FAQ
1.How can I place an order for LTC694CS8-3.3#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC694CS8-3.3#TRPBF 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 LTC694CS8-3.3#TRPBF reliable?
The price and inventory of LTC694CS8-3.3#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC694CS8-3.3#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC694CS8-3.3#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC694CS8-3.3#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC694CS8-3.3#TRPBF?
LTC694CS8-3.3#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC694CS8-3.3#TRPBF 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 LTC694CS8-3.3#TRPBF?
For technical support, including LTC694CS8-3.3#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC694CS8-3.3#TRPBF requirements.
6.How does Aetrix verify that LTC694CS8-3.3#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC694CS8-3.3#TRPBF 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 LTC694CS8-3.3#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC694CS8-3.3#TRPBF?
All LTC694CS8-3.3#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC694CS8-3.3#TRPBF, 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 LTC694CS8-3.3#TRPBF part is unused and in its original packaging.
Return procedure for LTC694CS8-3.3#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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