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Analog Devices Inc./Maxim Integrated MAX688ESA
- Part No.:
- MAX688ESA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX688ESA.pdf
- Description:
- IC REG LINEAR LDO
- Quantity:
- Payment:
- Shipping:
Inventory:46,694
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Product details
Overview
MAX688ESA from Maxim Integrated is a precision 3.3V fixed-output, low-dropout linear regulator requiring an external PNP pass transistor; delivers >1A output with ≥10mA base drive, features active-low SHDN control, power-fail monitoring (PFO), and operates from 2.7V to 11.0V input; used in portable telephones and battery-powered memory backup supplies.
For engineers reviewing the MAX688ESA datasheet, MAX688ESA pinout, MAX688ESA application, or MAX688ESA equivalent, this page provides verified specifications, SO-package terminal mapping, shutdown threshold behavior, dropout voltage vs. load data, and real-world design considerations for high-current LDO implementations with external pass transistors.
Technical Context
The MAX688ESA implements a precision bandgap reference and high-gain error amplifier to regulate 3.3V output via external PNP transistor base drive; its BLIM-BASE comparator limits base current to control output current without adding collector-side sensing resistance.
It uses a three-level SHDN input: >1.25V enables full operation, <1.2V enters standby (<25µA supply current), and <0.2V forces full shutdown (<1µA); PFO is open-drain and trips 170mV below nominal VOUT at 1mA base current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±2% over temperature and line/load - ensures stable logic supply for 3.3V microcontrollers and SRAM. |
| Input Voltage Range | 2.7V to 11.0V - supports single-cell Li-ion (3.0–4.2V) and multi-cell alkaline/NiMH inputs up to 9V. |
| Dropout Voltage | 40mV at 200mA (FZT749), 100mV at 650mA - enables regulation down to ~3.34V input at 650mA, minimizing wasted headroom. |
| SHDN Thresholds | VON = 1.25V (min), VSTBY = 1.2V (max), VSD = 0.2V (max) - allows precise, hysteresis-controlled sequencing using resistor dividers from VIN. |
| PFO Trip Point | 170mV below nominal VOUT (i.e., 3.13V at 3.3V output) - provides early warning before output falls out of regulation, enabling graceful system shutdown. |
| Supply Current | 150µA operating, <1µA in shutdown - extends battery life in always-on monitoring applications. |
| Operating Temp | –40°C to +85°C - qualified for industrial and automotive-adjacent portable equipment environments. |
Pinout & Package
MAX688ESA is housed in an 8-pin SO (Small Outline) package, 150 mil width, with gull-wing leads and JEDEC MS-012AC outline; RoHS-compliant, moisture sensitivity level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 IN | Positive input supply | Accepts 2.7V–11.0V; bypass capacitor (C1) must be placed directly between IN and GND for stability. |
| 2 SHDN | Active-low shutdown control | Three-state input: >1.25V = on, <1.2V = standby, <0.2V = full shutdown; open-drain PFO asserts low when SHDN < 0.2V. |
| 3 PFO | Power-fail open-drain output | Trips low when VOUT drops 170mV below nominal; sinks current only; requires external pull-up for logic-level signaling. |
| 4 GND | Analog and power ground | Common return for IN, OUT, CC, BASE, BLIM; must be low-impedance and star-connected near C2. |
| 5 OUT | Regulated 3.3V output | Drives external PNP emitter; connects to load and output capacitor C2 (≥10µF, low-ESR). |
| 6 BLIM | Base current limit sense | Monitors voltage across RB (BASE–BLIM); sets max base current as IBASE ≤ 0.1V / (RB + 5Ω) - enables programmable current limiting. |
| 7 BASE | PNP transistor base drive | Sources ≥10mA to external PNP base; internal current limiting prevents saturation-induced quiescent current rise during dropout. |
| 8 CC | Compensation node | Connects 10nF non-polarized capacitor to GND; stabilizes loop response and suppresses startup overshoot. |
Key Features
| Feature | Design Value |
|---|---|
| External PNP drive | Direct 10mA+ base current sourcing enables >1A output with high-hFE transistors (e.g., FZT749, β > 100), avoiding integrated pass device thermal limitations. |
| Programmable current limit | Resistor RB between BASE and BLIM sets precise base current ceiling - limits output current without degrading dropout voltage or requiring collector-sense resistors. |
| Early power-fail warning | PFO asserts 170mV before output leaves regulation - gives system controller time to save state or initiate controlled shutdown before brownout. |
| Three-level shutdown control | SHDN pin supports sequenced power management: full-on → low-IQ standby → ultra-low-IQ shutdown - ideal for battery runtime optimization. |
| Low-noise, high-PSRR regulation | 105µVRMS output noise and >40dB ripple rejection at 1kHz - suitable for noise-sensitive analog and mixed-signal loads. |
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 input. IC Role / Device Role / Timing Role: Primary 3.3V LDO supplying processor core and PMU; PFO signals impending brownout to trigger sleep mode entry. Use Value: Maintains regulation down to 3.34V input at 650mA, extending usable battery capacity by delaying cutoff until true end-of-discharge. |
Use Scenario: Providing clean, regulated 3.3V to CMOS SRAM during main power loss in industrial controllers. IC Role / Device Role / Timing Role: Standby regulator holding memory voltage while main supply fails; PFO triggers backup switchover before VOUT drops below 3.13V. Use Value: Prevents data corruption by ensuring SRAM remains powered above retention threshold (typically 2.0V) even after main supply collapse. |
| Portable Instruments | High-Efficiency Linear Regulator |
|
Use Scenario: Supplying precision ADCs, op-amps, and sensors in handheld multimeters and data loggers. IC Role / Device Role / Timing Role: Low-noise 3.3V source with <±2% accuracy and 105µVRMS noise - critical for 16-bit measurement integrity. Use Value: Eliminates need for post-regulation filtering; enables direct connection to high-resolution analog signal chains without added PSRR degradation. |
Use Scenario: Replacing inefficient switching regulators in EMI-sensitive medical or audio devices where clean DC is mandatory. IC Role / Device Role / Timing Role: High-current LDO (up to 4A with Darlington configuration) delivering 3.3V with <100mV dropout - minimizes heat vs. standard LDOs. Use Value: Achieves >90% efficiency at 3.5V input/3.3V output (94% at 650mA), surpassing typical IC-based LDOs while retaining low noise and fast transient response. |
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 |
|---|---|---|---|
| LT1528CS8#PBF | Integrated PNP pass device; 3.3V fixed; 3A output; no external transistor required; higher quiescent current (1.5mA) | Eliminates external transistor layout complexity but lacks programmable current limiting and has higher dropout (340mV @ 3A) | Select when board space is constrained and external transistor handling is undesirable; avoid when >1A output with minimal dropout is required. |
| TPS7A4701RGWR | Ultra-low noise (4.7µVRMS), adjustable output; 1A max; integrated pass FET; 310mV dropout @ 1A | Superior noise performance for RF/analog, but fixed 3.3V variants require external resistors; no PFO or SHDN hysteresis | Choose for noise-critical analog rails; not suitable when power-fail signaling or precise three-level shutdown control is needed. |
Compared with LT1528CS8#PBF and TPS7A4701RGWR, the MAX688ESA trades integration for superior dropout performance (<100mV @ 650mA), programmable current limiting via RB, and deterministic PFO/SHDN hysteresis - making it optimal for high-efficiency, high-current, battery-aware systems where external transistor use is acceptable.
Availability
MAX688ESA is available at Aetrix Electronics and suitable for portable telephones, battery-powered memory backup systems, and portable instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX688ESA 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) designs precision analog, mixed-signal, and power-management ICs for demanding industrial, communications, and consumer applications.
The MAX687/MAX688/MAX689 family was engineered specifically for high-accuracy, low-dropout regulation in battery-powered systems where external PNP transistors enable scalable current delivery without sacrificing efficiency or thermal performance.
FAQ
What is the maximum output current achievable with the MAX688ESA?
The MAX688ESA itself does not deliver output current directly - it drives the base of an external PNP transistor. With a high-gain transistor like the FZT749 (β > 100), the MAX688ESA's ≥10mA base drive enables >1A output. Using a Darlington configuration (e.g., TIP42 + 2N4403), the MAX688ESA supports up to 4A while maintaining low dropout. The actual limit depends on the selected PNP's hFE, power dissipation rating, and heatsinking.
Does the MAX688ESA have automatic shutdown like the MAX687?
No. Unlike the MAX687, the MAX688ESA does not feature automatic latched shutdown triggered by low output voltage. Instead, it relies entirely on the active-low SHDN pin for external control - entering standby (<25µA) when SHDN falls below 1.2V and full shutdown (<1µA) when SHDN drops below 0.2V. This provides flexible, user-defined power sequencing without reliance on output voltage monitoring.
What is the function of the BLIM pin on the MAX688ESA?
The BLIM pin on the MAX688ESA serves as the sense input for base-current limiting. When a resistor RB is placed between BASE and BLIM, the internal comparator regulates the voltage across RB to ~100mV, thereby setting IBASE ≤ 0.1V / (RB + 5Ω). This enables precise, programmable output current limiting without adding series resistance in the PNP collector path - preserving low dropout voltage while preventing excessive base drive during dropout conditions.
Can the MAX688ESA be used with a P-channel MOSFET instead of a PNP transistor?
No - the MAX688ESA is designed exclusively for NPN-driven PNP pass transistors. Its BASE pin sources current and expects a bipolar junction transistor with forward-biased base-emitter junction. A P-channel MOSFET requires gate-drive voltage referenced to source (not emitter), lacks inherent current gain, and would not respond correctly to the MAX688ESA's base-current limiting architecture. Use dedicated PMOS LDO controllers (e.g., MAX1725) for P-FET solutions.
What is the recommended value for the compensation capacitor (CC) on the MAX688ESA?
The recommended value for the CC capacitor on the MAX688ESA is 10nF, connected from pin 8 (CC) to GND. Non-polarized types (ceramic or polyester) are required to keep leakage current below 25nA; aluminum or tantalum electrolytics are unsuitable due to high leakage. Values up to 100nF may be used to eliminate startup overshoot, though this increases power-up time. The capacitor must be placed close to the IC with short traces.
MAX688ESA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- 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:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX688ESA FAQ
1.How can I place an order for MAX688ESA through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX688ESA 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 MAX688ESA reliable?
The price and inventory of MAX688ESA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX688ESA is usually 5 days.
3.What payment methods are accepted for MAX688ESA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX688ESA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX688ESA?
MAX688ESA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX688ESA 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 MAX688ESA?
For technical support, including MAX688ESA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX688ESA requirements.
6.How does Aetrix verify that MAX688ESA is sourced from the original manufacturer or authorized distributors?
All MAX688ESA 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 MAX688ESA meets industry standards.
7.What is the process for return or replacement of MAX688ESA?
All MAX688ESA units undergo pre-shipment inspection (PSI). If there is an issue with MAX688ESA, 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 MAX688ESA part is unused and in its original packaging.
Return procedure for MAX688ESA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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