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Analog Devices Inc. LTC1531CSW#TRPBF
- Part No.:
- LTC1531CSW#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Comparators
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LTC1531CSW#TRPBF.pdf
- Description:
- IC COMPARATOR 2 GEN PUR 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,135
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Product details
Overview
LTC1531CSW#TRPBF from Analog Devices (formerly Linear Technology) is a self-powered, capacitive-isolated dual differential comparator with 2500VRMS isolation, integrated 2.5V regulated output (5mA max), and zero-cross detection for triac control. It operates without an isolated supply, draws 10–14mA at VCC = 5V, and supports isolated thermistor temperature control, AC line voltage monitoring, and switch control in high-voltage industrial interfaces.
For engineers reviewing the LTC1531CSW#TRPBF datasheet, LTC1531CSW#TRPBF pinout, LTC1531CSW#TRPBF application, or LTC1531CSW#TRPBF equivalent, key selection criteria include its self-powered isolation architecture, 300Hz typical sample rate, 2.5V VREG pulsed output (108μs), dual differential input topology (V1–V4), and UL1577 recognition - all critical for safety-isolated sensing in AC mains-connected systems.
Technical Context
The LTC1531CSW#TRPBF implements a switched-capacitor isolation barrier that transfers both power and data across a 2500VRMS capacitive interface. Its isolated side cycles between power harvesting (via VPW capacitor charging) and brief active periods: a 108μs VREG pulse powers internal circuitry and CMPOUT, enabling one sampled comparison per power-listen cycle.
It features two independent comparator functions: a primary 4-input summing comparator (V1+V2)/2 > (V3+V4)/2 supporting differential or single-ended inputs, and a dedicated zero-cross comparator (ZCPOS/ZCNEG) with ±30mV offset and 200–800mV hysteresis, generating TTL-level ZCDATA pulses for triac triggering synchronized to AC line zero crossings.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Isolation Voltage | 2500VRMS (1 min), UL1577 recognized - enables direct connection to 120/240V AC mains without external isolation components. |
| VREG Output | 2.5V ±50mV, pulsed 108μs ON time, 5mA max load - powers external sensors (e.g., thermistor bridges) on isolated side with minimal quiescent drain. |
| Sample Rate | 200–300Hz typical under light load - determined by VPW capacitor recharge rate; non-uniform timing due to power-dependent listen-cycle activation. |
| Input Impedance | 300MΩ (balanced inputs), 18MΩ (unbalanced) - enables high-impedance sensor interfacing without loading effects on bridge circuits. |
| dV/dt Immunity | 50V/μs continuous - ensures reliable operation under fast-rising common-mode transients typical in motor drives and SMPS environments. |
| Zero-Cross Offset | ±30mV (typ), ±120mV (max) - defines minimum detectable zero-crossing amplitude, critical for accurate phase-angle control of triacs. |
| Supply Current | 10–14mA at VCC = 5V, SHDN = VCC - sets system-level power budget for powered-side logic and timing circuitry. |
Pinout & Package
Package: 28-lead plastic SO (SW), wide-body (0.300"), ISO-rated for 2500VRMS isolation. Pin pitch: 0.050", body width: 0.394–0.419", lead count: 28.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC (1) | Powered-side supply input | 5V nominal input; powers internal timing, transmit logic, and shutdown circuitry on non-isolated side. |
| SHDN (2) | Active-low shutdown control | Pulls DATA low and disables internal oscillation; reduces supply current to ≤10μA when asserted. |
| ZCNEG (3), ZCPOS (4) | Zero-cross comparator inputs | Dedicated differential inputs for AC line phase-shifted signals; ESD-clamped, rail-to-rail common-mode range. |
| VPW (11) | Isolated-side power storage node | Connects to external capacitor (≥1μF); self-regulates at ~3.3V; enables comparator only when ≥3.3V reached. |
| CMPOUT (12) | Latched isolated comparator output | Driven by VREG during its 108μs ON window; used for hysteresis feedback (e.g., in temperature controllers). |
| VREG (13) | Isolated 2.5V regulated output | Pulsed reference source; supplies CMPOUT and external sensors; not Hi-Z during OFF time - avoid large capacitive loads. |
| ISOGND (14) | Isolated-side ground reference | Must float relative to GND; forms return path for VREG, CMPOUT, and V1–V4 inputs on isolated side. |
| V1–V4 (15–18) | Dual differential comparator inputs | Summing inputs: comparison result = (V1+V2)/2 > (V3+V4)/2; supports midsupply referencing via VREG/2. |
| VALID (25) | Data-valid strobe | 200ns-delayed pulse indicating new DATA latched; used to clock external registers or microcontroller inputs. |
| DATA (26) | Latched comparator result | Holds last valid comparison outcome (logic 0/1); resets to 0 on power-up or SHDN assertion. |
| ZCDATA (27) | Zero-cross trigger pulse | 24–30μs TTL pulse generated only when DATA = 1 AND ZCPOS–ZCNEG crosses zero with sufficient hysteresis margin. |
| GND (28) | Powered-side ground | Low-impedance return for VCC, SHDN, and output drivers; must be separated from ISOGND by isolation barrier. |
Key Features
| Feature | Design Value |
|---|---|
| Self-powered isolation | No secondary supply required: power and data transferred across capacitive barrier using VPW storage capacitor. |
| Dual comparator architecture | One 4-input summing comparator for precision sensing + dedicated zero-cross comparator for AC line synchronization. |
| Integrated 2.5V reference | VREG provides regulated, pulsed 2.5V output (108μs) with 4–15Ω output impedance - powers external analog circuitry safely. |
| UL1577 recognition | File E151738 certified - meets reinforced insulation requirements for functional safety in industrial and medical AC-connected equipment. |
| High common-mode immunity | 50V/μs dV/dt rejection and 2500VRMS isolation enable reliable operation in noisy motor drive, power supply, and grid-tied applications. |
Applications
| Isolated Thermistor Temperature Control | AC Line Zero-Cross Triac Control |
|---|---|
Use Scenario: Monitoring HVAC or industrial heater temperature via YSI 44008 thermistor in 120V AC-coupled environment. IC Role / Device Role / Timing Role: LTC1531CSW#TRPBF performs isolated differential comparison of thermistor bridge against VREG/2 reference and generates ZCDATA pulses synchronized to AC zero crossing. Use Value: Enables closed-loop temperature regulation with <±0.5°C hysteresis while maintaining 2500VRMS galvanic isolation between sensor and MCU. |
Use Scenario: Phase-angle dimming or motor speed control using triac driven from 60Hz AC mains. IC Role / Device Role / Timing Role: LTC1531CSW#TRPBF's ZCPOS/ZCNEG inputs sense RC-phase-shifted AC waveform; ZCDATA triggers triac gate at precise delay after zero crossing. Use Value: Achieves jitter-free, noise-immune firing with ±30mV zero-cross offset - eliminates false triggering in EMI-heavy environments. |
| Isolated Battery Cell Monitor | Isolated Voltage Sense (Delta-Sigma) |
Use Scenario: Monitoring individual Li-ion cell voltages in series-connected battery packs with floating grounds. IC Role / Device Role / Timing Role: LTC1531CSW#TRPBF isolates each cell's voltage (divided to ≤2.5V) and compares against 0.89V threshold derived from VREG. Use Value: Detects cell under-voltage (<1.786V) with no shared ground between cells or host controller - prevents ground loop errors and fault propagation. |
Use Scenario: High-resolution DC voltage measurement (0–2.5V) in PLC analog input modules requiring 10-second settling time. IC Role / Device Role / Timing Role: LTC1531CSW#TRPBF uses CMPOUT's 108μs ON pulses at ~300Hz to modulate charge into R-C integrator (delta-sigma principle). Use Value: Delivers 4mV resolution and 10sec effective time constant without op-amps on isolated side - reduces component count and leakage sensitivity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated comparator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADUM3190TRWZ | Galvanically isolated error amplifier (not comparator); 2.5V reference output; 10kVRMS isolation; requires external comparator. | Targeted at isolated feedback loops in DC-DC converters, not discrete sensing or zero-cross control. | Select when closed-loop regulation (e.g., SMPS feedback) is needed, not open-loop threshold detection or triac timing. |
| ISO124U | Analog isolator (not self-powered); requires separate isolated supply; 2500VRMS; no integrated comparator or VREG. | Suitable for isolated analog signal transmission only; cannot replace LTC1531CSW#TRPBF's integrated sensing + power + logic functions. | Choose only if existing design already provides isolated power and needs pure analog isolation - adds BOM cost and complexity. |
Compared with ADUM3190TRWZ and ISO124U, the LTC1531CSW#TRPBF uniquely integrates self-powered isolation, dual comparator functionality, zero-cross detection, and a 2.5V pulsed reference in a single SO-28 package - eliminating external power conversion, reference ICs, and discrete comparators required by alternatives.
Availability
LTC1531CSW#TRPBF is available at Aetrix Electronics and suitable for isolated thermistor temperature control, AC line zero-cross triac control, and isolated battery cell monitoring requiring stable component supply, long-term lifecycle support, and UL-recognized safety certification.
Supply support for LTC1531CSW#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies for precision instrumentation, industrial automation, and power management.
The LTC1531CSW#TRPBF belongs to Linear's legacy isolated interface product line, designed specifically for self-powered, safety-certified sensing in AC mains-connected industrial controls, energy metering, and appliance systems where galvanic isolation and low-power operation are mandatory.
FAQ
What is the isolation rating and safety certification of the LTC1531CSW#TRPBF?
The LTC1531CSW#TRPBF provides 2500VRMS isolation rated per UL1577 (File E151738). It is not certified to IEC 60747-5-2 or VDE 0884-10. The isolation barrier uses internal capacitors formed in the lead frame of the SW28 package, enabling reinforced insulation for functional safety in industrial equipment. This rating applies to the full operating temperature range (0°C to 70°C) and is validated for 1 minute at 2500VRMS.
How does the LTC1531CSW#TRPBF achieve self-powered operation across the isolation barrier?
The LTC1531CSW#TRPBF uses a capacitive isolation barrier to transfer energy from the powered side (VCC) to the isolated side via VPW. During the "power cycle", charge is pumped onto an external capacitor (typically 1μF) connected to VPW. When VPW reaches ~3.3V, the isolated circuit activates, pulses VREG for 108μs, and performs one comparator sampling. No external isolated supply is needed - the entire function is sustained by this cyclic energy transfer.
What is the function of the CMPOUT pin on the LTC1531CSW#TRPBF, and how is it used in practice?
The CMPOUT pin on the LTC1531CSW#TRPBF outputs the latched result of the previous isolated comparator decision, driven by VREG during its 108μs ON window. In practice, it is used to implement hysteresis - for example, feeding CMPOUT back to V3/V4 to shift the trip point based on prior state. It is not continuously active and goes Hi-Z when VREG is off, making it ideal for low-power, event-driven feedback in temperature controllers.
Can the LTC1531CSW#TRPBF interface directly with a microcontroller GPIO, and what are the voltage levels?
Yes - the DATA, VALID, and ZCDATA outputs of the LTC1531CSW#TRPBF are TTL-compatible. At VCC = 4.5V, VOH ≥ 3.0V (IO = –400μA) and VOL ≤ 0.4V (IO = 1.6mA), ensuring reliable interfacing with 3.3V or 5V microcontrollers. VALID is delayed 200ns after DATA, allowing clean edge-aligned capture. All three outputs are actively driven - no pull-ups required.
What is the maximum continuous dV/dt the LTC1531CSW#TRPBF can withstand across its isolation barrier?
The LTC1531CSW#TRPBF guarantees 50V/μs continuous common-mode dV/dt immunity. Beyond this, the isolated side may fail to detect the end of the power cycle, disrupting sampling. This specification is derived from the internal timing architecture and verified by design (not tested per unit). For higher transient immunity, external filtering or slower switching topologies are recommended - the device is not rated for >50V/μs sustained slew rates.
LTC1531CSW#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- General Purpose
- Number of Elements:
- 2
- Output Type:
- -
- Voltage - Supply, Single/Dual (±):
- -
- :
- -
- Voltage - Input Offset (Max):
- -
- Current - Input Bias (Max):
- 5mA
- Current - Output (Typ):
- 14mA
- Current - Quiescent (Max):
- -
- CMRR, PSRR (Typ):
- -
- Propagation Delay (Max):
- -
- Hysteresis:
- 0°C ~ 70°C
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- Surface Mount
- :
- 28-SOIC
LTC1531CSW#TRPBF FAQ
1.How can I place an order for LTC1531CSW#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1531CSW#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 LTC1531CSW#TRPBF reliable?
The price and inventory of LTC1531CSW#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1531CSW#TRPBF is usually 5 days.
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We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1531CSW#TRPBF transactions.
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4.How is shipping managed for LTC1531CSW#TRPBF?
LTC1531CSW#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1531CSW#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 LTC1531CSW#TRPBF?
For technical support, including LTC1531CSW#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1531CSW#TRPBF requirements.
6.How does Aetrix verify that LTC1531CSW#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1531CSW#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 LTC1531CSW#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1531CSW#TRPBF?
All LTC1531CSW#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1531CSW#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 LTC1531CSW#TRPBF part is unused and in its original packaging.
Return procedure for LTC1531CSW#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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