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Analog Devices Inc./Maxim Integrated MAX1688EUE
- Part No.:
- MAX1688EUE
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
MAX1688EUE.pdf
- Description:
- IC REG BOOST ADJ 730MA 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,748
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Product details
Overview
MAX1688EUE from Maxim Integrated is a step-up DC-DC converter optimized for GSM RF power amplifier burst-load applications, featuring adaptive constant-recharge-time current limiting, 1.25V to 6V adjustable output voltage, 2.7V to 6V input range (1 Li-Ion or 3 NiMH cells), and 90% peak efficiency at 5V/2A GSM burst load.
For engineers reviewing the MAX1688EUE datasheet, MAX1688EUE pinout, MAX1688EUE application, or MAX1688EUE equivalent, key selection criteria include its adaptive recharge-time algorithm for battery life optimization, TSSOP-16 package with dual MOSFET drivers, synchronous rectification eliminating external Schottky diodes, and logic-controlled standby mode to suppress switching noise during RF transmit bursts.
Technical Context
The MAX1688EUE implements hysteretic inductor-current control with peak current set by the CHG pin voltage via an external resistor, enabling self-regulating reservoir capacitor recharge time that compensates for input voltage sag and output capacitor ESR variation. Its functional diagram integrates internal P- and N-channel MOSFETs, a precision 1.25V reference, and feedback transconductance of 200µA/V.
Unlike the MAX1687EUE's fixed voltage-controlled current limit, the MAX1688EUE uses sample-and-hold circuitry to monitor output droop after each burst and dynamically adjust peak inductor current-ensuring consistent recharge time across varying load duty cycles, battery state-of-charge, and temperature (–40°C to +85°C).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7V to 6V - supports single Li-Ion (3.0–4.2V), three NiMH (3.6V nominal), or three alkaline cells without external regulation. |
| Output Voltage Range | 1.25V to 6V - set externally via resistor divider on FB pin; regulated to ±2% over temperature and line/load. |
| Peak Efficiency | 90% - achieved at 5V output, 2A GSM burst load, minimizing thermal stress and extending battery runtime. |
| Shutdown Current | 3µA - enables ultra-low-power system sleep states without compromising fast wake-up capability. |
| Switching Frequency | Exceeds 1MHz - determined by inductor value and load; allows use of compact 10µH inductors and reduces output ripple. |
| Adaptive Recharge Algorithm | Constant-time recovery - samples post-burst VOUT droop to set next-cycle IPEAK, maintaining stable reservoir capacitor recharge regardless of battery aging or temperature drift. |
| Package | 16-pin TSSOP (1.1mm max height) - surface-mount, thermally enhanced for high-current pulsed operation in space-constrained handheld designs. |
Pinout & Package
MAX1688EUE is housed in a 16-pin thin shrink small-outline package (TSSOP) with 0.65mm pitch and 1.1mm maximum height, optimized for low-profile portable electronics. Thermal pad is not present; PGND pins (6, 7, 8, 9) and AGND (10) must be connected to a low-inductance ground plane using star grounding per layout guidelines.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2 | IN | Battery input connection; requires ≥47µF low-ESR ceramic bypass capacitor directly at pin to suppress high-frequency switching transients. |
| 3, 4 | LX1 | N-channel MOSFET source terminal; connects to one end of power inductor and internal current-sense resistor. |
| 5 | ON | Logic-level enable/disable control; low for >1.2ms triggers 3µA shutdown; synchronized low during RF burst eliminates switching noise coupling into PA stage. |
| 6, 7, 8, 9 | PGND | Power ground return for LX1/LX2 paths; must be star-connected to input/output capacitors to minimize ground bounce during 2A burst currents. |
| 10 | AGND | Analog ground reference for FB, REF, CHG; isolated from PGND except at single-point star ground to prevent noise injection into feedback loop. |
| 11, 12 | LX2 | Drain node of internal P- and N-channel MOSFETs; connects to second inductor terminal and output reservoir capacitor anode. |
| 13, 14 | OUT | Regulated output; supplies GSM PA during burst; requires low-ESR bulk capacitor (e.g., 2000µF tantalum) to limit VOUT droop to <10% at 2.66A/4.62ms. |
| 15 | FB | Feedback input; regulates output to 1.25V reference; resistor divider from OUT to GND sets final VOUT with ±2% accuracy. |
| 16 | CHG | Constant-recharge-time programming input; external resistor to GND (e.g., 40.2kΩ) sets peak inductor current and thus reservoir recharge time. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive constant-recharge-time algorithm | Self-adjusts peak inductor current based on measured VOUT droop, ensuring consistent reservoir capacitor recharge time across battery discharge, temperature, and capacitor aging. |
| Internal synchronous rectification | Eliminates need for external Schottky diode, reducing BOM count and PCB area while improving efficiency by >5% versus diode-based boost topologies. |
| Logic-controlled standby mode | Disables switching during RF transmit bursts (ON = low), preventing noise coupling into sensitive RF front-end circuits without interrupting power delivery from reservoir capacitor. |
| Precision 1.25V reference | Stable ±1% reference (1.212V–1.288V) with <10µA max output current, enabling accurate resistor-divider VOUT setting and supporting external DAC-based current limit control. |
| Gentle start-up sequence | Four-phase soft-start (Linear → Pseudo Buck → Pseudo Boost → Boost) limits inrush current, preventing battery voltage sag and system reset during initial power application. |
Applications
| GSM Mobile Handsets | Wireless LAN PC Cards |
|---|---|
Use Scenario: Powering RF power amplifier during 12% duty-cycle, 2.66A GSM transmit bursts from a single Li-Ion cell. IC Role / Device Role / Timing Role: Step-up DC-DC converter with adaptive recharge control; delivers peak current from reservoir capacitor while limiting battery surge to ≤450mA. Use Value: Extends usable battery life by 18% versus non-adaptive converters and reduces VBAT sag below brownout threshold during deep discharge. | Use Scenario: Supplying 5V/350mA continuous load in PCMCIA wireless adapter with intermittent 1A burst demands. IC Role / Device Role / Timing Role: Adjustable-output boost regulator with ON-pin synchronization; enters standby during host bus arbitration to eliminate conducted EMI. Use Value: Enables compliance with PCMCIA EMI Class B limits while maintaining 90% efficiency at full load without heatsinking. |
| Industrial Telematics Modules | Portable Medical Data Transmitters |
Use Scenario: Providing stable 3.3V/1A output from 3×NiMH battery pack (3.6V–4.5V) in GPS/GSM dual-mode vehicle trackers. IC Role / Device Role / Timing Role: Input-voltage-agile boost converter with undervoltage lockout (2.7V); maintains regulation down to end-of-discharge while minimizing battery current spikes. Use Value: Delivers 20% longer operational runtime between charges compared to fixed-current-limit alternatives under real-world pulsed load profiles. | Use Scenario: Powering Bluetooth LE transmitter in handheld diagnostic device requiring low-noise, low-quiescent operation between periodic 500ms data bursts. IC Role / Device Role / Timing Role: Low-noise DC-DC with 3µA shutdown and precise 1.25V reference; enables microcontroller-controlled ON sequencing for zero-crossing burst timing. Use Value: Reduces average system current by 42% versus always-on regulators, extending AA battery life to >12 months in typical usage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up DC-DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX1687EUE | Uses voltage-controlled LIM pin for fixed current limit (0–1V input); lacks CHG pin and adaptive recharge logic. | Suitable for systems with known, stable burst profiles and fixed reservoir capacitor size; no droop compensation. | Select MAX1687EUE when cost sensitivity outweighs battery life optimization and design uses microcontroller-driven current limit adjustment. |
| TPS61040DRVR | Fixed 28V OVP, no adaptive recharge, 500kHz fixed frequency, lower 0.5A peak switch current rating. | Targeted at general-purpose boost applications (LCD bias, white LED); not validated for GSM burst timing or reservoir capacitor management. | Choose TPS61040DRVR only for non-GSM, non-burst applications where 2A peak load capability and adaptive recharge are unnecessary. |
Compared with MAX1687EUE and TPS61040DRVR, the MAX1688EUE uniquely delivers battery-life-maximizing adaptive recharge control, integrated dual-MOSFET drivers rated for 2A burst loads, and ON-pin synchronization specifically architected for GSM/RF burst-noise suppression-making it irreplaceable in high-efficiency, low-noise mobile RF power delivery.
Availability
MAX1688EUE is available at Aetrix Electronics and suitable for GSM handsets, wireless PC cards, industrial telematics modules, and portable medical transmitters requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for MAX1688EUE 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 semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for demanding applications in communications, computing, and industrial systems.
The MAX1687/MAX1688 product line was designed specifically for GSM and wireless handset burst-load power delivery, integrating adaptive current limiting, synchronous rectification, and noise-suppressing standby modes to maximize battery life and RF system integrity.
FAQ
What is the primary function of the CHG pin on the MAX1688EUE?
The CHG pin on the MAX1688EUE sets the adaptive constant-recharge-time behavior by accepting an external resistor to ground. This resistor determines the peak inductor current during reservoir capacitor recharge, enabling the MAX1688EUE to maintain consistent recovery time despite variations in input voltage, output droop, or capacitor ESR. Unlike the MAX1687EUE's LIM pin, CHG enables closed-loop droop compensation critical for GSM battery life extension.
Can the MAX1688EUE operate with a 3.3V input to generate 5V output?
Yes, the MAX1688EUE operates across a 2.7V to 6V input range, including 3.3V. At VIN = 3.3V and VOUT = 5V, typical efficiency exceeds 85% at 300mA DC load and remains above 80% during 1A GSM burst loads, as confirmed in the Typical Operating Characteristics graphs. The device's hysteretic control ensures stable regulation even with input voltage sag common in Li-Ion discharge curves.
How does the MAX1688EUE reduce switching noise during RF transmission?
The MAX1688EUE reduces switching noise during RF transmission by entering standby mode when the ON pin is driven low. In this state, the internal MOSFETs disable, inductor current ramps to zero, and the output disconnects from the input-eliminating all switching activity while the reservoir capacitor continues powering the RF PA. This feature is explicitly designed for GSM burst synchronization and prevents noise coupling into sensitive RF receiver paths.
What is the recommended output capacitor for a 2.66A GSM burst load on the MAX1688EUE?
For a 2.66A GSM burst load with 4.62ms pulse duration and <10% allowable VOUT droop, the MAX1688EUE datasheet specifies a 2000µF low-ESR tantalum or polymer capacitor. This value ensures droop remains below 360mV, preserving PA linearity and preventing brownout. The capacitor must be placed within 5mm of the OUT and PGND pins, with short, wide traces to minimize ESL-induced ringing.
Does the MAX1688EUE require an external Schottky diode?
No, the MAX1688EUE does not require an external Schottky diode because it integrates synchronous rectification using internal P- and N-channel MOSFETs. This architecture achieves >90% peak efficiency and eliminates reverse-recovery losses and thermal issues associated with discrete diodes-reducing bill-of-materials cost and PCB footprint while improving reliability in high-pulse-current applications.
MAX1688EUE Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Up
- Output Configuration:
- Positive
- Topology:
- Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 6V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 6V
- Current - Output:
- 730mA (Switch)
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
MAX1688EUE FAQ
1.How can I place an order for MAX1688EUE through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1688EUE 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 MAX1688EUE reliable?
The price and inventory of MAX1688EUE are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1688EUE is usually 5 days.
3.What payment methods are accepted for MAX1688EUE?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1688EUE transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1688EUE?
MAX1688EUE orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1688EUE 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 MAX1688EUE?
For technical support, including MAX1688EUE datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1688EUE requirements.
6.How does Aetrix verify that MAX1688EUE is sourced from the original manufacturer or authorized distributors?
All MAX1688EUE 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 MAX1688EUE meets industry standards.
7.What is the process for return or replacement of MAX1688EUE?
All MAX1688EUE units undergo pre-shipment inspection (PSI). If there is an issue with MAX1688EUE, 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 MAX1688EUE part is unused and in its original packaging.
Return procedure for MAX1688EUE:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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