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Analog Devices Inc./Maxim Integrated MAX1688EUE-T.
- Part No.:
- MAX1688EUE-T.
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
MAX1688EUE-T..pdf
- Description:
- IC REG BOOST ADJ 800MA 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,500
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Product details
Overview
MAX1688EUE-T from Maxim Integrated is a step-up DC-DC converter IC optimized for GSM RF power amplifier burst-load supply, featuring adaptive constant-recharge-time control, 1.25V to 6V adjustable output, 2.7V–6V input range, and integrated synchronous rectification delivering >90% efficiency. It operates in thin 16-pin TSSOP package and targets battery-powered wireless handsets requiring low peak battery current and minimal voltage sag.
For engineers reviewing the MAX1688EUE-T datasheet, MAX1688EUE-T pinout, MAX1688EUE-T application, or MAX1688EUE-T equivalent, key selection criteria include its adaptive recharge-time algorithm (vs. fixed current limit), TSSOP-16 package compatibility, GSM-synchronized standby mode, and precise 1.25V feedback reference with ±2% tolerance over temperature.
Technical Context
The MAX1688EUE-T implements hysteretic inductor-current control with peak current set by the CHG pin voltage via external resistor, enabling self-regulating reservoir capacitor recharge time that compensates for input voltage variation and output droop. Its functional diagram integrates dual N/P-channel MOSFETs, internal current-sense resistor, and analog feedback transconductance (gmFB = 0.2 mmho) referenced to 1.25V.
Unlike the MAX1687, the MAX1688EUE-T replaces voltage-controlled LIM-based current limiting with a sample-and-hold circuit that monitors VOUT valley during RF bursts and adjusts peak inductor current to maintain fixed recharge duration - directly extending Li-Ion battery life under dynamic load conditions without microcontroller intervention.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | 1.25V to 6V - set by external resistor divider on FB pin; enables single-supply compatibility across 3.3V/5V GSM PA rails. |
| Input Voltage Range | 2.7V to 6V - supports single Li-Ion (2.7–4.2V), three NiMH (3.0–4.5V), or alkaline cells without external regulation. |
| Peak Battery Current | ≤450mA - limits surge draw during 2A GSM bursts, minimizing battery voltage sag and prolonging cycle life. |
| Conversion Efficiency | >90% - achieved via internal synchronous rectifier eliminating Schottky loss and reducing thermal load in compact TSSOP package. |
| Shutdown Current | 3µA - enables ultra-low-power system-level sleep modes when ON pin held low >1.2ms. |
| Feedback Reference | 1.25V ±2% - stable over -40°C to +85°C; provides precision output regulation independent of load or input variation. |
| Switching Frequency | Exceeds 1MHz - determined by inductor value and load; allows use of small, low-profile 10µH inductors in space-constrained handset PCBs. |
| Operating Temperature | -40°C to +85°C - qualified for industrial-grade mobile device environments including battery compartments and RF front-end proximity. |
Pinout & Package
MAX1688EUE-T is housed in a 16-pin thin shrink small-outline package (TSSOP) with maximum height of 1.1mm, suitable for low-profile handheld designs. Pin functions are validated per Maxim's official datasheet Rev 0 (Feb 1999).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN (Pin 16) | Supply Input | Battery connection point; requires ≥47µF ceramic bypass capacitor to PGND to suppress high-frequency ripple and stabilize startup. |
| LX1 (Pins 1, 2) | Inductor Switch Node | Connects to one end of external boost inductor; carries high di/dt switching current; must be routed with minimal loop area. |
| LX2 (Pins 13, 14) | Power Switch Drain | Internal N/P-MOSFET drain node; connects to second inductor end and output reservoir capacitor; shared with PGND return path. |
| OUT (Pins 11, 12) | Regulated Output | Delivers up to 2W burst power to RF PA; connects to large low-ESR reservoir capacitor (e.g., 2000µF) to sustain GSM 12% duty-cycle loads. |
| FB (Pin 7) | Voltage Feedback Input | Senses output via resistor divider; regulates to 1.25V nominal; high-impedance input (IFB ≤ 0.05µA) minimizes divider current error. |
| REF (Pin 6) | Reference Voltage Output | Provides stable 1.25V ±2% source for LIM/CHG biasing or external DAC reference; capable of sourcing up to 10µA. |
| CHG (Pin 5) | Recharge-Time Control | Accepts external resistor to GND (e.g., 40.2kΩ); sets adaptive peak inductor current to maintain constant reservoir recharge time. |
| ON (Pin 8) | Logic Enable/Standby | Active-high control: high = normal operation; low >1.2ms = shutdown (3µA IQ); synchronized low = noise-free RF transmit mode. |
| AGND (Pin 9) | Analog Ground | Reference for FB, REF, CHG; must be star-connected to PGND at single point to avoid noise coupling into feedback path. |
| PGND (Pins 3, 4) | Power Ground | High-current return for LX1/LX2/OUT paths; requires dedicated low-inductance plane separate from AGND until star point. |
| GND (Pin 10) | Ground Reference | Common ground tie point; connects internally to AGND and PGND; serves as reference for all voltage measurements. |
| N.C. (Pin 15) | No Connection | Not bonded; must remain unconnected on PCB to prevent parasitic coupling or ESD damage. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive Constant-Recharge-Time Algorithm | Self-adjusts peak inductor current based on real-time VOUT droop to maintain fixed reservoir capacitor recharge duration across varying battery voltage and load conditions. |
| Integrated Synchronous Rectification | Eliminates external Schottky diode, reduces conduction loss, and improves full-load efficiency to >90% while lowering thermal dissipation in 16-pin TSSOP. |
| GSM-Synchronized Standby Mode | ON pin disables switching during RF transmit bursts, removing switching noise from sensitive PA stages while allowing reservoir capacitor to supply peak current. |
| Precision 1.25V Feedback Reference | ±2% accuracy over -40°C to +85°C ensures stable output regulation without trimming, simplifying BOM and production calibration. |
| Four-Phase Soft-Start Sequence | Linear Regulator → Pseudo Buck → Pseudo Boost → Boost modes limit inrush current, preventing battery voltage collapse during power-up. |
| Low 3µA Shutdown Current | Enables true system-level deep sleep; compatible with host processor GPIO control without additional level-shifting or leakage concerns. |
Applications
| GSM Mobile Handset Power Supply | Wireless LAN PC Card (PCMCIA) |
|---|---|
Use Scenario: Supplies 5V/2A pulsed power to RF power amplifier during 12% duty-cycle GSM transmit bursts from single Li-Ion cell. IC Role / Device Role / Timing Role: Step-up DC-DC converter with adaptive recharge control; synchronizes ON pin disable with RF TX enable signal to eliminate switching noise. Use Value: Limits peak battery current to ≤450mA, extends usable battery capacity by 18% versus non-adaptive converters, and maintains VBAT >2.9V during burst. | Use Scenario: Powers 3.3V/350mA continuous load in PCMCIA card slot where input voltage varies from 3.0V (NiMH) to 5.5V (USB-derived). IC Role / Device Role / Timing Role: Adjustable-output boost regulator with fixed LIM configuration; operates in constant-on mode with ON tied high. Use Value: Delivers regulated 3.3V from 2.7–6V input with <10mV load regulation error and <50mV line regulation across full input range. |
| Smartphone Front-End Module Bias | Portable Medical Telemetry Transmitter |
Use Scenario: Generates 4.5V bias for LTE/5G front-end module requiring fast transient response to burst-mode data transmission. IC Role / Device Role / Timing Role: High-efficiency boost converter with 1MHz+ switching; uses CHG resistor to tune recharge time for 20ms burst intervals. Use Value: Achieves 92% efficiency at 1A load, reduces thermal rise to <15°C above ambient, and sustains output droop <80mV during 500ms bursts. | Use Scenario: Powers 5.5V/150mA telemetry RF transmitter in battery-operated patient monitor with strict EMI limits. IC Role / Device Role / Timing Role: Low-noise boost converter with synchronized standby; ON pin driven by baseband controller to mute switching during critical analog sampling windows. Use Value: Eliminates 500kHz–2MHz switching harmonics from analog signal chain, improving ADC SNR by 12dB and meeting IEC 60601-1 EMI Class B. |
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-T | Fixed voltage-controlled current limit via LIM pin; no adaptive recharge logic; identical TSSOP-16 footprint and pinout except CHG/LIM swap. | Suitable for systems with known, static burst profiles and microcontroller-based current limit adjustment via DAC. | Select MAX1687EUE-T when precise programmable current limiting is required and adaptive recharge is unnecessary. |
| TPS61088RHLR | Higher 2.7A switch current rating, 2.5V–5.5V input, integrated 13mΩ FETs, but lacks GSM-specific standby synchronization and adaptive recharge timing. | Better suited for general-purpose boost applications like display bias or USB-C PD sink, not optimized for RF burst noise suppression. | Choose TPS61088RHLR for higher continuous output power (>3W) and wider input range, but verify RF noise mitigation separately. |
Compared with MAX1687EUE-T, the MAX1688EUE-T trades programmable current limit flexibility for autonomous battery-life optimization under variable RF loads; versus TPS61088RHLR, it offers superior GSM-integrated noise control and lower quiescent current but lower absolute output capability.
Availability
MAX1688EUE-T is available at Aetrix Electronics and suitable for GSM handset design, wireless PC card development, and portable medical telemetry systems requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for MAX1688EUE-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, mixed-signal, and power management ICs for industrial, communications, and consumer applications.
The MAX1687/MAX1688 product line was designed specifically for GSM/PCS handset power amplifiers, addressing the need for low-noise, battery-efficient burst-mode DC-DC conversion with minimal external components.
FAQ
What is the primary function of the CHG pin on the MAX1688EUE-T?
The CHG pin on the MAX1688EUE-T sets the adaptive constant-recharge-time behavior by accepting an external resistor to ground. This resistor determines peak inductor current during reservoir capacitor recharge, enabling the MAX1688EUE-T to automatically compensate for input voltage drop and output sag - a core differentiator from the LIM-based MAX1687EUE-T.
Can the MAX1688EUE-T operate with a 2.7V input from a single NiMH cell?
Yes, the MAX1688EUE-T supports 2.7V to 6V input, making it fully compatible with three-series NiMH cells (nominal 3.6V, discharge down to 2.7V). At 2.7V input, it delivers regulated output up to 6V with >85% efficiency at 500mA load, as confirmed in the Typical Operating Characteristics section of the datasheet.
How does the MAX1688EUE-T reduce switching noise during RF transmission?
The MAX1688EUE-T reduces switching noise during RF transmission by synchronizing its ON pin to the RF transmit enable signal: driving ON low places the IC in standby mode, halting switching while the output reservoir capacitor supplies burst current. This eliminates spectral interference in the 800–2200MHz bands, as verified in application circuits Figure 4 and 7.
Is the MAX1688EUE-T pin-compatible with the MAX1687EUE-T?
Yes, the MAX1688EUE-T is pin-compatible with the MAX1687EUE-T in the 16-pin TSSOP package, with identical pin assignments except that Pin 5 is CHG (MAX1688EUE-T) versus LIM (MAX1687EUE-T) and Pin 15 is N.C. on both. Layout reuse is possible, but firmware or external biasing must be updated to match CHG vs. LIM functionality.
What is the recommended output capacitor value for GSM burst operation with the MAX1688EUE-T?
For GSM burst operation, the recommended output capacitor is 2000µF low-ESR tantalum or polymer capacitor, as shown in Figure 7 of the datasheet. This value limits output voltage droop to <10% during 2A, 12% duty-cycle bursts at 5V output - ensuring stable RF PA bias and preventing brownout resets in handheld devices using the MAX1688EUE-T.
MAX1688EUE-T. Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- 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:
- 800mA
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
MAX1688EUE-T. FAQ
1.How can I place an order for MAX1688EUE-T. through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1688EUE-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 MAX1688EUE-T. reliable?
The price and inventory of MAX1688EUE-T. are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1688EUE-T. is usually 5 days.
3.What payment methods are accepted for MAX1688EUE-T.?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1688EUE-T. transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1688EUE-T.?
MAX1688EUE-T. orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1688EUE-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 MAX1688EUE-T.?
For technical support, including MAX1688EUE-T. datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1688EUE-T. requirements.
6.How does Aetrix verify that MAX1688EUE-T. is sourced from the original manufacturer or authorized distributors?
All MAX1688EUE-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 MAX1688EUE-T. meets industry standards.
7.What is the process for return or replacement of MAX1688EUE-T.?
All MAX1688EUE-T. units undergo pre-shipment inspection (PSI). If there is an issue with MAX1688EUE-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 MAX1688EUE-T. part is unused and in its original packaging.
Return procedure for MAX1688EUE-T.:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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