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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:2,669
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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 control, 1.25V to 6V adjustable output voltage, 2.7V to 6V input range, and 90% peak efficiency. It limits peak battery current to ~450mA while delivering up to 2A at 5V during 12% duty-cycle bursts, enabling extended Li-Ion battery life in compact wireless handsets.
For engineers reviewing the MAX1688EUE+ datasheet, MAX1688EUE+ pinout, MAX1688EUE+ application, or MAX1688EUE+ equivalent, key selection criteria include its adaptive recharge-time algorithm (vs. fixed current limit in MAX1687), TSSOP-16 package with dual LX pins, shutdown current of 3µA, and precise 1.25V feedback reference with ±2% tolerance over temperature.
Technical Context
The MAX1688EUE+ implements hysteretic inductor-current control with programmable peak current via the CHG pin, using an internal sample-and-hold circuit that monitors output voltage droop to dynamically adjust recharge time-ensuring consistent reservoir capacitor recovery across varying input voltage, load burst depth, and capacitor ESR. Its dual MOSFET architecture integrates both P-channel and N-channel switches with on-resistances of 0.7Ω and 0.18Ω respectively.
Unlike the MAX1687, the MAX1688EUE+ replaces the LIM voltage-controlled current-limit input with the CHG pin, enabling self-regulating recharge behavior synchronized to RF transmit timing via the ON pin. The device transitions through four startup phases (Linear → Pseudo Buck → Pseudo Boost → Boost) to minimize inrush current, and disconnects OUT from IN during shutdown via internal power MOSFET isolation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | 1.25V to 6V, set by external resistor divider on FB pin; enables flexible rail generation for RF PA biasing. |
| 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 Efficiency | 90%, achieved at moderate loads (e.g., 300mA @ 5.5V out); reduces thermal stress and extends battery runtime in burst-mode operation. |
| Shutdown Current | 3µA typical, minimizing standby drain in always-on mobile devices where ON pin is held low between RF bursts. |
| Feedback Reference | 1.25V ±2% over -40°C to +85°C, providing stable output regulation despite temperature-induced battery voltage sag. |
| Switching Frequency | Exceeds 1MHz (inductor-dependent), enabling use of small, low-profile 10µH inductors and reducing EMI filter size. |
| Peak Battery Current | 450mA typical under GSM 2A/5V burst, limiting surge demand on aging Li-Ion cells and preventing system brownouts. |
Pinout & Package
MAX1688EUE+ is housed in a 16-pin thin-shrink small-outline package (TSSOP) with maximum height of 1.1mm, suitable for space-constrained mobile PCBs. Thermal pad is not present; PGND and AGND are separate pins for noise isolation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN | Supply Input | Battery connection point; requires ≥47µF low-ESR bypass capacitor to stabilize input during high di/dt bursts. |
| OUT | Regulated Output | High-current output node feeding reservoir capacitor; isolated from IN during shutdown to prevent backfeed. |
| LX1 / LX2 | Power Switch Nodes | LX1 connects to inductor high-side; LX2 is dual-drain node for integrated P- and N-channel MOSFETs-critical for synchronous rectification. |
| PGND / AGND | Ground Returns | Separate power and analog grounds reduce switching noise coupling into FB/REF paths; must be star-connected near IC. |
| FB | Voltage Feedback | Senses output via resistor divider; regulates to 1.25V nominal-accuracy directly determines output voltage tolerance. |
| REF | Reference Output | 1.25V buffered reference (10µA max sink/source); usable to bias LIM/CHG circuits or external DACs in TSSOP packages. |
| ON | Control Enable | Active-high logic input; low for >1.2ms forces 3µA shutdown; synchronized low during RF transmit eliminates switching noise injection. |
| CHG | Recharge-Time Set | Connects external resistor to GND to program constant-recharge-time algorithm-key differentiator vs. MAX1687's LIM pin. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive Constant-Recharge-Time | Self-adjusts peak inductor current based on real-time VOUT droop, maintaining consistent reservoir capacitor recharge time across battery voltage decay and load variation. |
| Internal Synchronous Rectifier | Eliminates external Schottky diode-reducing BOM count, board area, and conduction losses versus asynchronous boost topologies. |
| Four-Phase Soft-Start | Sequences Linear → Pseudo Buck → Pseudo Boost → Boost modes to limit inrush current and prevent battery voltage collapse at power-up. |
| Output Disconnect in Shutdown | Internally isolates OUT from IN during shutdown, preventing reverse current flow and protecting downstream circuitry from unregulated discharge. |
| GSM Burst Optimization | ON pin synchronization allows precise disabling during RF transmit windows-removing switching noise from sensitive PA stages without sacrificing energy delivery. |
Applications
| GSM Mobile Handsets | Wireless LAN Client Devices |
|---|---|
Use Scenario: Delivering short-duration, high-current pulses (2A @ 5V, 12% duty cycle) to RF power amplifiers during TDMA transmit slots. IC Role / Device Role / Timing Role: Step-up DC-DC converter with adaptive recharge control, synchronized to ON pin to enter standby during RF bursts and supply energy from reservoir capacitor. Use Value: Limits peak battery current to 450mA, preventing voltage sag-induced resets and extending usable battery capacity by >15% versus non-adaptive converters. | Use Scenario: Powering 2.4GHz/5GHz WLAN transceivers in PCMCIA cards or embedded modules requiring burst-mode efficiency. IC Role / Device Role / Timing Role: High-efficiency boost regulator managing dynamic load transients; CHG pin configures recharge time to match variable WLAN packet lengths. Use Value: Achieves 90% efficiency at 300mA load while maintaining <100mV output droop during 1A bursts-enabling compact 2000µF reservoir capacitors. |
| PC Card (PCMCIA) Power Management | Low-Power Cellular IoT Modules |
Use Scenario: Providing regulated 3.3V or 5V rails for hot-pluggable PC cards with strict inrush and peak current limits per socket specification. IC Role / Device Role / Timing Role: Adjustable-output boost converter with soft-start and output disconnect, ensuring safe insertion and compliance with PCMCIA power sequencing requirements. Use Value: Four-phase startup limits inrush to <500mA, while 3µA shutdown current meets ultra-low-power sleep mode mandates for card idle states. | Use Scenario: Supplying burst-capable power to NB-IoT or LTE-M modems operating on single-cell Li-Ion batteries with deep discharge profiles. IC Role / Device Role / Timing Role: Adaptive current-limited boost converter compensating for declining VIN (2.7V–4.2V) and maintaining stable VOUT during periodic data transmissions. Use Value: CHG-based recharge algorithm sustains >85% efficiency down to 2.7V input, enabling reliable modem operation even at end-of-battery-life voltage. |
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 LIM pin for voltage-controlled current limit instead of CHG; lacks adaptive recharge algorithm; same TSSOP-16 package and pinout except LIM↔CHG swap. | Fixed current limit suits predictable burst loads; less effective for varying battery voltage or capacitor aging. | Select MAX1687EUE+ when microcontroller-driven current adjustment is required or when design reuses existing LIM-based layout. |
| TPS61088RHLR | Higher 2.5A switch current, 2.7V–12V input, but no adaptive recharge or ON-synchronized standby; uses current-mode PWM control. | Better for continuous high-current loads; lacks GSM-specific noise suppression features like ON-triggered shutdown. | Choose TPS61088RHLR for wider input range or higher output current needs, but verify RF noise immunity in burst-mode operation. |
Compared with MAX1687EUE+, the MAX1688EUE+ delivers superior battery life under variable burst conditions via its adaptive recharge algorithm, while TPS61088RHLR offers broader input capability at the cost of GSM-optimized noise control and lower quiescent current.
Availability
MAX1688EUE+ is available at Aetrix Electronics and suitable for GSM handsets, wireless LAN client devices, PCMCIA power management, and low-power cellular IoT modules requiring stable component supply, long-term lifecycle support, 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) designs precision analog, mixed-signal, and power-management ICs for demanding industrial, communications, and consumer applications.
The MAX1687/MAX1688 product line was engineered specifically for GSM/EDGE RF power amplifier power delivery, addressing battery surge current limitation, RF noise isolation, and adaptive energy replenishment in space-constrained mobile platforms.
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 algorithm by connecting an external resistor to ground. Unlike the MAX1687's LIM pin, CHG enables the IC to monitor output voltage droop during RF bursts and dynamically adjust peak inductor current-ensuring consistent reservoir capacitor recharge time across varying battery voltage, load depth, and capacitor aging. This feature is central to the MAX1688EUE+'s extended battery life advantage.
Can the MAX1688EUE+ operate with a single Li-Ion cell?
Yes, the MAX1688EUE+ supports input voltages from 2.7V to 6V, making it fully compatible with single Li-Ion cells (nominal 3.6V, operating range 2.7–4.2V). Its adaptive recharge algorithm maintains efficiency and stable output regulation even as the cell discharges below 3.0V, and the 450mA peak battery current limit prevents excessive voltage sag that could reset baseband processors.
How does the MAX1688EUE+ reduce RF interference during transmission?
The MAX1688EUE+ reduces RF interference by synchronizing its ON pin to the GSM transmit window: driving ON low during RF bursts places the IC in standby mode, halting switching activity and eliminating switching noise injection into sensitive PA stages. During standby, the charged reservoir capacitor supplies burst current-ensuring clean RF performance without compromising power delivery. This behavior is explicitly designed into the MAX1688EUE+'s functional architecture.
What is the significance of separate PGND and AGND pins on the MAX1688EUE+?
The MAX1688EUE+ features separate PGND (power ground) and AGND (analog ground) pins to isolate high-di/dt switching return currents from precision analog feedback paths. PGND carries LX1/LX2 and OUT switching currents, while AGND serves FB, REF, and CHG-minimizing noise coupling that could destabilize regulation or degrade reference accuracy. Proper star grounding of both pins near the IC is essential to achieve specified 1.25V ±2% FB tolerance and low-noise operation.
Does the MAX1688EUE+ require an external Schottky diode?
No, the MAX1688EUE+ does not require an external Schottky diode because it integrates a synchronous rectifier using internal P-channel and N-channel MOSFETs. This eliminates conduction losses associated with external diodes, improves efficiency to 90%, reduces thermal dissipation, and simplifies PCB layout-directly supporting the compact form factor requirements of GSM handset designs where the MAX1688EUE+ is deployed.
MAX1688EUE+ 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:
- Last Time Buy
- 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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