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Analog Devices Inc./Maxim Integrated MAX687CSA+
- Part No.:
- MAX687CSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX687CSA+.pdf
- Description:
- IC REG LINEAR 3.3V 1A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,444
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Product details
Overview
The MAX687CSA+ from Maxim Integrated is a precision 3.3V fixed-output, low-dropout linear regulator requiring an external PNP pass transistor (e.g., FZT749) to deliver >1A output current. It features automatic latched shutdown at VOUT < 2.96V, integrated power-fail monitoring (PFO), and 10mA minimum base-drive capability. Designed for battery-powered portable telephones and memory backup supplies where deep discharge prevention is critical.
For engineers reviewing the MAX687CSA+ datasheet, MAX687CSA+ pinout, MAX687CSA+ application, or MAX687CSA+ equivalent, this page delivers verified technical context-including dropout voltage vs. load, ON-pin startup timing, PFO threshold hysteresis, and SO-8 package thermal derating-essential for reliable low-voltage system design and battery protection implementation.
Technical Context
The MAX687CSA+ implements a precision bandgap reference with internal comparators monitoring VOUT for both power-fail warning (PFO trip at 170mV below nominal) and automatic latched shutdown (at 2.96V). Its ON input requires a high pulse sustained until VOUT exceeds the shutdown threshold to latch on, preventing false start-up during slow-rising or noisy supply conditions.
Base drive is delivered via the BASE pin with current limiting set by an external resistor (RB) between BASE and BLIM, enabling accurate output current limiting without collector-sense resistors. The CC pin connects to a 10nF non-polarized compensation capacitor to stabilize loop response and suppress overshoot during power-up.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 3.3V ±2% - Ensures stable logic supply for 3.3V microcontrollers and SRAM in battery-backed systems. |
| Dropout Voltage | 40mV at 200mA (FZT749) - Enables regulation down to VIN = 3.34V, critical for extending battery runtime. |
| Supply Current | 150µA operating / <1µA shutdown - Minimizes quiescent drain during standby, preserving battery life. |
| PFO Threshold | 2.96V shutdown / 3.13V PFO trip - Provides 170mV early warning before latched shutdown, allowing graceful system save. |
| Input Voltage Range | 2.7V to 11.0V - Supports single-cell Li-ion (3.0–4.2V), dual-cell NiMH (2.4–3.0V), and regulated 5V rails. |
| Base Drive | ≥10mA - Sufficient to drive high-hFE PNP transistors (β > 100) for >1A output without external boost. |
| Package | 8-pin SO (SOIC) - Industry-standard surface-mount footprint with 471mW max power dissipation at +70°C. |
Pinout & Package
MAX687CSA+ is housed in an 8-pin SO (Small Outline) package per JEDEC MS-012, with 1.27mm lead pitch and 4.9mm × 6.0mm body size. Thermal derating is 5.88mW/°C above +70°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 IN | Positive input supply | Accepts 2.7V–11.0V; bypass capacitor (C1) must connect directly between IN and GND for stability. |
| 2 ON | Active-high enable control | Pulse high to initiate startup; must remain high until VOUT > 2.96V to latch on; connect to VIN if unused. |
| 3 PFO | Power-fail open-drain output | Sinks current when VOUT ≤ 3.13V; sources/sinks in MAX687; remains low during shutdown. |
| 4 GND | Analog/digital ground reference | Common return for IN, OUT, CC, and external PNP emitter; must be low-impedance plane. |
| 5 OUT | Regulated 3.3V output | Drives load via external PNP collector; requires ≥10µF low-ESR output capacitor (C2). |
| 6 BLIM | Base-current limit sense | Resistor (RB) between BASE and BLIM sets IBASE ≤ 0.1V/(RB + 5Ω); enables current limiting without VCE penalty. |
| 7 BASE | PNP transistor base driver | Delivers ≥10mA drive; short to BLIM for max base current; connects to PNP base with minimal trace length. |
| 8 CC | Compensation node | Connect 10nF non-polarized capacitor to GND; controls loop stability and eliminates power-on overshoot. |
Key Features
| Feature | Design Value |
|---|---|
| Latched automatic shutdown | Triggers at 2.96V and holds OFF until ON pin receives clean high pulse-prevents battery cell reversal in portable instruments. |
| Integrated power-fail comparator | Trips PFO 170mV below nominal (3.13V) with 7mV hysteresis-enables early warning for data save before shutdown. |
| External PNP base-current limiting | RB resistor sets precise IBASE limit without collector sensing-maintains low dropout while controlling IOUT accuracy. |
| Low-noise 150µA operation | Enables use in noise-sensitive analog sections; <1µA shutdown current extends shelf life of battery-backed memory. |
| Line transient rejection | <2mV output deviation for 3.4V→3.6V input steps-ensures stable 3.3V rail during battery voltage fluctuations. |
Applications
| Portable Telephones | Battery-Powered Memory Backup |
|---|---|
Use Scenario: Powering RF front-end and baseband ICs in GSM/CDMA handsets with single Li-ion cell. IC Role / Device Role / Timing Role: Primary 3.3V LDO regulator with battery-discharge cutoff to prevent cell damage below 3.0V. Use Value: Extends usable battery capacity by 8–12% versus fixed-threshold shutdown, while ensuring PFO-triggered save operations complete. |
Use Scenario: Maintaining CMOS SRAM voltage during main power loss in industrial controllers. IC Role / Device Role / Timing Role: Standby regulator with latched shutdown and PFO-driven interrupt to initiate RAM save sequence. Use Value: Guarantees ≥100ms hold-up time after AC failure via early PFO alert, enabling full register dump before VOUT collapse. |
| Portable Test Instruments | Low-Power Data Loggers |
Use Scenario: Supplying ADC, sensor interface, and microcontroller in handheld multimeters. IC Role / Device Role / Timing Role: Precision 3.3V reference source with tight line/load regulation (<45mV) for measurement accuracy. Use Value: Output accuracy <±2% and <0.4mV/V line regulation ensure consistent ADC reference across battery discharge curve. |
Use Scenario: Regulating microcontroller and flash memory in solar-charged environmental sensors. IC Role / Device Role / Timing Role: Ultra-low-quiescent regulator with <1µA shutdown mode to minimize self-discharge during long sleep cycles. Use Value: Reduces annual battery leakage by >95% versus standard LDOs, enabling 5+ year field deployment on primary cells. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar low-dropout linear regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX688CSA+ | Same 3.3V output and SO-8 package, but uses active-low SHDN instead of ON; no automatic shutdown-requires external control logic. | Used where programmable enable/disable is needed (e.g., MCU-controlled power sequencing), not battery-protection shutdown. | Select MAX688CSA+ only if system-level control of enable timing is required and latched shutdown is undesirable. |
| LT1528CS8#PBF | 3.3V fixed output, 3A capable, integrated PNP-no external transistor needed; higher quiescent current (1.2mA vs. 150µA). | Preferred for high-current (>500mA), space-constrained designs where external transistor layout is impractical. | Choose LT1528CS8#PBF when board area is limited and >500mA continuous load justifies higher IQ and cost premium. |
Compared with MAX687CSA+, MAX688CSA+ trades autonomous battery protection for flexible system control, while LT1528CS8#PBF eliminates external transistor complexity at the cost of 8× higher quiescent current-making MAX687CSA+ optimal for ultra-low-power, battery-critical applications.
Availability
MAX687CSA+ is available at Aetrix Electronics and suitable for portable telephones, battery-powered memory backup systems, and portable test instruments requiring stable component supply with guaranteed long-term lifecycle support.
Supply support for MAX687CSA+ 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
Maxim Integrated (now part of Analog Devices) is a U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs.
The MAX687CSA+ belongs to Maxim's precision low-dropout linear regulator family, engineered specifically for battery-powered systems demanding autonomous low-voltage shutdown, power-fail warning, and minimal quiescent current.
FAQ
What is the function of the ON pin on the MAX687CSA+?
The ON pin on the MAX687CSA+ is an active-high enable input that initiates regulator startup. A high pulse must be applied and held until VOUT rises above 2.96V to latch the device ON. If the ON pin is left unconnected, it must be tied to VIN; leaving it floating may cause erratic behavior. This latching mechanism ensures reliable turn-on only when sufficient input voltage is present, preventing partial regulation during brown-out conditions.
Does the MAX687CSA+ include an internal pass transistor?
No, the MAX687CSA+ does not include an internal pass transistor. It is a controller IC that drives an external PNP transistor (e.g., FZT749) via its BASE pin. This architecture allows scalable output current-from hundreds of mA to >4A-by selecting appropriate external transistors and heat sinking, while maintaining low dropout determined solely by the PNP's VCE(SAT).
How does the PFO output behave during shutdown of the MAX687CSA+?
During shutdown, the PFO output of the MAX687CSA+ is actively driven low and sinks current regardless of the actual VOUT level. This behavior provides a deterministic fault signal to host logic. Unlike normal operation-where PFO trips low at 3.13V-the shutdown state forces PFO low to indicate that the regulator has entered latched-off mode, enabling unambiguous system-level power-fail response.
What is the recommended value for the compensation capacitor (CC) on the MAX687CSA+?
The recommended value for the compensation capacitor (CC) on the MAX687CSA+ is 10nF, connected between CC pin and GND. Ceramic or polyester non-polarized capacitors are required to keep leakage current below 25nA; aluminum or tantalum electrolytics are unsuitable due to excessive leakage. Values up to 100nF may be used to eliminate power-on overshoot, though they increase startup time.
Can the MAX687CSA+ be used with input voltages below 3.3V?
Yes, the MAX687CSA+ can operate with input voltages as low as 2.7V, but regulation is only maintained while VIN exceeds VOUT plus the dropout voltage. At 200mA load with FZT749, dropout is 40mV-so regulation holds down to VIN ≈ 3.34V. Below that, VOUT collapses linearly. The internal comparators remain functional down to 2.7V, enabling PFO alert and shutdown even during deep dropout, making it viable for end-of-battery-life detection.
MAX687CSA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 11V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 0.04V @ 200mA (Typ)
- Current - Output:
- 1A
- Current - Quiescent (Iq):
- 25 µA
- Current - Supply (Max):
- 250 µA
- PSRR:
- -
- Control Features:
- Current Limit, Enable, Power Fail
- Protection Features:
- -
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX687CSA+ FAQ
1.How can I place an order for MAX687CSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX687CSA+ 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 MAX687CSA+ reliable?
The price and inventory of MAX687CSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX687CSA+ is usually 5 days.
3.What payment methods are accepted for MAX687CSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX687CSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX687CSA+?
MAX687CSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX687CSA+ 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 MAX687CSA+?
For technical support, including MAX687CSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX687CSA+ requirements.
6.How does Aetrix verify that MAX687CSA+ is sourced from the original manufacturer or authorized distributors?
All MAX687CSA+ 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 MAX687CSA+ meets industry standards.
7.What is the process for return or replacement of MAX687CSA+?
All MAX687CSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX687CSA+, 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 MAX687CSA+ part is unused and in its original packaging.
Return procedure for MAX687CSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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