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Analog Devices Inc./Maxim Integrated MAX688CUA+T
- Part No.:
- MAX688CUA+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
MAX688CUA+T.pdf
- Description:
- IC REG LINEAR 3.3V 1A 8UMAX
- Quantity:
- Payment:
- Shipping:
Inventory:2,816
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Product details
Overview
MAX688CUA+T from Maxim Integrated is a 3.3V fixed-output, high-accuracy low-dropout linear regulator requiring an external PNP pass transistor. It delivers up to 1A output current with 40mV dropout at 200mA (FZT749), features active-low shutdown control (SHDN), power-fail monitoring (PFO), and operates from 2.7V to 11.0V input. It is used in portable telephones and battery-powered memory backup supplies.
For engineers reviewing the MAX688CUA+T datasheet, MAX688CUA+T pinout, MAX688CUA+T application, or MAX688CUA+T equivalent, this page provides verified technical context, real-world design meaning for key specs, validated pin functions, confirmed alternatives, and supply-chain support for industrial and embedded OEM designs.
Technical Context
The MAX688CUA+T implements precision voltage regulation using an external PNP transistor as the pass element, with base drive sourced internally up to 10mA minimum. Its SHDN input enables three-level operation: on (>1.25V), standby (<1.2V, <25µA supply), and full shutdown (<0.2V, <1µA supply).
It integrates a power-fail comparator (PFO) that trips 170mV below nominal VOUT (3.3V) at 1mA base current and provides open-drain output. Unlike the MAX687, it lacks automatic latched shutdown - shutdown is fully controlled via SHDN, with 70mV hysteresis between on/standby thresholds.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±2% - ensures stable logic supply for 3.3V microcontrollers and SRAM without external feedback. |
| Dropout Voltage | 40mV at 200mA (FZT749) - enables regulation down to VIN = 3.34V, critical for single-cell Li-ion or 3-cell NiMH systems. |
| Input Voltage Range | 2.7V to 11.0V - supports wide battery chemistries (Li-ion, NiMH, alkaline) and unregulated wall adapters. |
| SHDN Thresholds | VON = 1.25V min, VSTBY = 1.2V max, VSD = 0.2V max - allows precise, hysteresis-stabilized external control using resistor dividers. |
| PFO Trip Point | VOUT − 170mV (at IBASE = 1mA) - provides early warning of output droop before system reset or data loss occurs. |
| Supply Current | 150µA operating, <1µA in shutdown - extends battery life in always-on backup circuits. |
| Package | 8-pin µMAX (3mm × 3mm) - enables compact, high-density PCB layouts for portable equipment. |
Pinout & Package
MAX688CUA+T is housed in an 8-pin µMAX package (3mm × 3mm, 0.65mm pitch), specified for 0°C to +70°C operation. Pin 1 is IN; pin 2 is SHDN; pin 3 is PFO; pin 4 is GND; pin 5 is OUT; pin 6 is BLIM; pin 7 is BASE; pin 8 is CC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 IN | Positive input supply | Accepts 2.7V–11.0V unregulated input; bypass capacitor must be placed directly between IN and GND. |
| 2 SHDN | Active-low shutdown control | Three-state input: >1.25V = on, <1.2V = standby (<25µA), <0.2V = full shutdown (<1µA); hysteresis prevents chatter. |
| 3 PFO | Power-fail open-drain output | Asserts low when VOUT drops 170mV below 3.3V; sinks current only - requires external pull-up for logic interfacing. |
| 4 GND | Analog and power ground | Common reference for all internal comparators, regulators, and external PNP emitter connection. |
| 5 OUT | Regulated 3.3V output | Delivers up to 1A via external PNP; connects to load and output capacitor C2 (min 10µF, low-ESR). |
| 6 BLIM | Base-current limit sense | Forms current-limit network with BASE pin; RB resistor sets max base drive: IBASE ≤ 0.1V/(RB + 5Ω). |
| 7 BASE | PNP transistor base driver | Sources up to 10mA to external PNP base; internal current limiting protects during dropout or overload. |
| 8 CC | Compensation node | Connects to GND via 10nF non-polarized capacitor (ceramic/polyester); stabilizes loop and suppresses startup overshoot. |
Key Features
| Feature | Design Value |
|---|---|
| External PNP drive | Direct 10mA min base-current sourcing enables >1A output with high-hFE transistors (e.g., FZT749, β > 100). |
| Low dropout performance | 40mV at 200mA (FZT749) - minimizes heat dissipation and extends usable battery voltage range. |
| Programmable base-current limit | Resistor (RB) between BASE and BLIM sets precise IBASE cap, enabling predictable ILOAD limiting without collector-sense penalty. |
| Power-fail warning | PFO asserts 170mV before VOUT fails - gives host MCU time to save state or initiate graceful shutdown. |
| Three-mode shutdown control | SHDN supports on/standby/shutdown states with defined thresholds and hysteresis - enables flexible power sequencing. |
Applications
| Portable Telephony Power Management | Battery Backup for CMOS SRAM |
|---|---|
Use Scenario: Regulating Li-ion battery output (3.0–4.2V) to stable 3.3V for RF transceiver and baseband ICs in GSM handsets. IC Role / Device Role / Timing Role: Primary LDO controller managing external PNP pass transistor; provides clean, low-noise 3.3V rail with fast transient response. Use Value: 40mV dropout preserves battery runtime; PFO alerts system before brownout; SHDN enables software-controlled sleep mode. |
Use Scenario: Maintaining 3.3V supply to static RAM during main power failure in industrial controllers or medical devices. IC Role / Device Role / Timing Role: Standby regulator holding memory voltage during AC loss; activated by SHDN signal from power-monitoring circuit. Use Value: <1µA shutdown current prevents battery depletion over weeks; PFO triggers backup switchover before data corruption. |
| High-Efficiency Portable Instrumentation | Low-Power Data Acquisition Node |
Use Scenario: Powering 3.3V ADCs, op-amps, and microcontrollers in handheld multimeters or gas detectors. IC Role / Device Role / Timing Role: Precision voltage source with tight line/load regulation (<±2%) and low noise (105µVRMS) for analog signal chain integrity. Use Value: <2mV line transient response ensures measurement stability during battery voltage sag; 150µA quiescent current extends field-use duration. |
Use Scenario: Supplying sensor interface and BLE radio in battery-operated environmental monitors deployed for months. IC Role / Device Role / Timing Role: Always-on regulator with programmable shutdown - wakes system on sensor event, then returns to ultra-low-power standby. Use Value: Three-level SHDN control reduces average current to sub-µA levels; µMAX package fits in space-constrained IoT enclosures. |
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 |
|---|---|---|---|
| MAX687CUA+T | Includes automatic latched shutdown triggered at VOUT < 2.96V; uses ON pin instead of SHDN; PFO sources/sinks current. | Used where self-protecting battery discharge prevention is required without external control logic. | Select MAX687CUA+T only if automatic shutdown on low VOUT is mandatory and ON pulse control is acceptable. |
| MAX689CUA+T | 3.0V fixed output; identical SHDN/PFO architecture and pinout; same µMAX package and temperature range. | Direct substitute where 3.0V logic or memory supply is needed instead of 3.3V. | Choose MAX689CUA+T when system voltage rails require 3.0V - pin-compatible and functionally identical except output voltage. |
Compared with MAX687CUA+T, the MAX688CUA+T offers externally controllable shutdown instead of auto-latch, making it suitable for systems requiring dynamic power sequencing. Against MAX689CUA+T, it differs solely in output voltage (3.3V vs. 3.0V), with identical control behavior, package, and thermal specs.
Availability
MAX688CUA+T is available at Aetrix Electronics and suitable for portable telephony, battery-backed memory systems, and low-power instrumentation requiring stable component supply across extended production lifecycles.
Supply support for MAX688CUA+T 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 and mixed-signal ICs for power, sensing, and communication applications.
The MAX687/MAX688/MAX689 family was designed specifically for high-accuracy, low-dropout regulation in battery-critical portable systems, emphasizing minimal dropout, precise power-fail detection, and flexible external transistor control.
FAQ
What is the maximum output current supported by the MAX688CUA+T?
The MAX688CUA+T itself does not deliver output current directly - it drives an external PNP transistor. With a high-gain device like the FZT749 (β > 100), it supports >1A output. The actual limit depends on the PNP's hFE, power dissipation capability, and heatsinking. Base current is limited to ≤10mA, so ILOAD(MAX) ≈ 10mA × hFE(MIN). For example, with hFE = 100, MAX688CUA+T enables ~1A output.
Does the MAX688CUA+T have built-in short-circuit protection?
No, the MAX688CUA+T does not include direct short-circuit protection. It limits base current to the external PNP transistor via the BLIM-BASE resistor network, which indirectly limits output current based on the transistor's hFE. Protection relies on proper selection of the external PNP and its thermal design - the IC itself does not monitor or clamp output current independently of the pass device.
Can the MAX688CUA+T be used with a P-channel MOSFET instead of a PNP transistor?
No - the MAX688CUA+T is designed exclusively for PNP bipolar junction transistors. Its base-drive architecture, current-limiting scheme, and internal reference assume BJT characteristics (e.g., ~0.7V VBE, current-controlled gain). A P-channel MOSFET requires gate-voltage drive and has no base current, making it incompatible with the MAX688CUA+T's BASE/BLIM interface and current-limiting mechanism.
What is the purpose of the CC pin on the MAX688CUA+T?
Pin 8 (CC) is the compensation capacitor terminal. A 10nF non-polarized capacitor (e.g., ceramic or polyester) must be connected from CC to GND to stabilize the control loop, prevent oscillation, and suppress startup overshoot. Using polarized capacitors (e.g., tantalum or aluminum electrolytic) is prohibited due to leakage current, which shifts output voltage and PFO thresholds. Higher values (up to 100nF) reduce overshoot but increase startup time.
How does the PFO output behave during shutdown of the MAX688CUA+T?
When SHDN is pulled below 0.2V, the MAX688CUA+T enters full shutdown (<1µA supply current) and the PFO pin is forced low regardless of the actual VOUT level. This provides a reliable "power-fail" assertion during intentional shutdown, simplifying system-level power sequencing. PFO remains low until SHDN rises above 1.25V and regulation resumes - it does not float or go high in shutdown.
MAX688CUA+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- 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-uMAX/uSOP
MAX688CUA+T FAQ
1.How can I place an order for MAX688CUA+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX688CUA+T 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 MAX688CUA+T reliable?
The price and inventory of MAX688CUA+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX688CUA+T is usually 5 days.
3.What payment methods are accepted for MAX688CUA+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX688CUA+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX688CUA+T?
MAX688CUA+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX688CUA+T 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 MAX688CUA+T?
For technical support, including MAX688CUA+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX688CUA+T requirements.
6.How does Aetrix verify that MAX688CUA+T is sourced from the original manufacturer or authorized distributors?
All MAX688CUA+T 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 MAX688CUA+T meets industry standards.
7.What is the process for return or replacement of MAX688CUA+T?
All MAX688CUA+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX688CUA+T, 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 MAX688CUA+T part is unused and in its original packaging.
Return procedure for MAX688CUA+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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