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Analog Devices Inc./Maxim Integrated MAX1687ESA
- Part No.:
- MAX1687ESA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX1687ESA.pdf
- Description:
- IC REG BOOST ADJ 730MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,075
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Product details
Overview
MAX1687ESA from Maxim Integrated is a step-up DC-DC converter optimized for GSM RF power amplifier burst-load applications, delivering up to 2W from 2.7V–6V input (single Li-Ion or three NiMH cells), featuring precise voltage-controlled current limit via LIM pin, internal synchronous rectification (>90% efficiency), and 3µA shutdown current. It reduces battery surge current by charging a reservoir capacitor between bursts, minimizing voltage sag in wireless handsets.
For engineers reviewing the MAX1687ESA datasheet, MAX1687ESA pinout, MAX1687ESA application, or MAX1687ESA equivalent, key selection considerations include its 8-pin SO package, adaptive current-limit architecture (distinct from MAX1688's CHG-based recharge control), peak battery current limitation to 450mA, and compatibility with GSM 12% duty-cycle pulsed loads requiring low-noise standby during RF transmit.
Technical Context
The MAX1687ESA implements hysteretic inductor-current control with programmable peak current (IPEAK) set by an external 0–1V voltage on the LIM pin, enabling precise battery current limiting without external sense resistors. Its dual-MOSFET topology integrates P-channel and N-channel switches with internal current-sense resistor (RSENSE = 0.7Ω typical) and precharge PMOS (30Ω) for controlled start-up.
It operates across four sequential start-up phases-Linear Regulator, Pseudo Buck, Pseudo Boost, and full Boost-to maintain stable battery current and suppress inrush. Standby mode disables switching during RF bursts (via ON pin), disconnecting output from input while allowing the reservoir capacitor to supply load current, eliminating switching noise coupling into sensitive RF circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7V to 6V - supports single Li-Ion (fully discharged to 2.7V) or three NiMH/alkaline cells without external regulation. |
| Output Voltage Range | 1.25V to 6V - adjustable via external resistor divider on FB pin; regulated to 1.25V feedback threshold. |
| Peak Battery Current Limit | 450mA - programmable via 0–1V on LIM pin; enables optimization of Li-Ion battery life vs. reservoir capacitor size. |
| Conversion Efficiency | >90% - achieved via integrated synchronous rectifier, eliminating external Schottky diode and associated conduction loss. |
| Shutdown Current | 3µA - ultra-low quiescent draw in shutdown (ON < 0.6V for >1.2ms), critical for standby power budget in portable devices. |
| Switching Frequency | Exceeds 1MHz - determined by inductor value and load; enables use of small, low-profile magnetics in space-constrained GSM modules. |
| Operating Temperature | –40°C to +85°C - qualified for industrial and mobile handset environments with no derating required. |
Pinout & Package
MAX1687ESA is housed in an 8-pin SO (Small Outline) package, 1.75mm height, JEDEC MS-012AC compliant, with gull-wing leads suitable for automated assembly and reflow soldering.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 IN | Supply Input | Battery input connection; requires ≥47µF bypass capacitor to PGND to stabilize input impedance during burst loads. |
| 2 LX1 | Inductor Switch Node | Connects to one end of boost inductor; carries high di/dt switching current; must be routed with minimal loop area. |
| 3 LX2 | Power Switch Drain | Drain node of internal N- and P-channel MOSFETs; ties to second inductor terminal and PGND return path. |
| 4 PGND | Power Ground | High-current ground return for LX1/LX2 paths; must be star-connected to input/output capacitors to minimize ground bounce. |
| 5 AGND | Analog Ground | Reference ground for FB, REF, and LIM; isolated from PGND at PCB level to prevent noise coupling into feedback loop. |
| 6 FB | Feedback Input | Senses output voltage via resistor divider; regulates VOUT to 1.25V nominal; high-impedance input (IFB < 0.1µA). |
| 7 ON | Enable/Standby Control | Logic-level input: high = normal operation; low >1.2ms = shutdown (3µA); low during RF burst = noise-free standby mode. |
| 8 LIM | Current-Limit Adjust | 0–1V analog input sets peak battery current (ILIM = VLIM × 0.86A/V – 0.06A); clamped internally at 1.25V. |
Key Features
| Feature | Design Value |
|---|---|
| Precise voltage-controlled current limit | LIM pin accepts 0–1V to linearly program ILIM from 200mA to 450mA, enabling exact battery current tailoring per GSM burst profile. |
| Integrated synchronous rectification | Eliminates external Schottky diode, reducing BOM count and conduction losses-critical for >90% efficiency at 2A GSM burst loads. |
| Four-phase soft-start sequence | Linear → Pseudo Buck → Pseudo Boost → Boost transitions limit inrush current and prevent system reset due to battery droop at power-up. |
| Output disconnect in shutdown | Internal switch isolates OUT from IN during shutdown, preventing reverse current flow and preserving reservoir capacitor charge for next burst. |
| GSM-synchronized standby mode | ON pin assertion during RF transmit halts switching, removing switching noise from PA bias path while maintaining output voltage via reservoir cap. |
Applications
| GSM Mobile Handset Power Management | Wireless LAN PC Card (PCMCIA) |
|---|---|
Use Scenario: Supplying 2A, 5V RF power amplifier bursts with 12% duty cycle in dual-band GSM phones operating from single Li-Ion cell. IC Role / Device Role / Timing Role: Step-up converter with synchronized standby; delivers peak energy from reservoir capacitor during transmit, recharges between bursts. Use Value: Limits peak battery current to 450mA, extending usable battery life by 18% versus non-limited converters and reducing voltage sag below 2.7V threshold. | Use Scenario: Powering 3.3V/5V WLAN baseband and PA circuits in hot-pluggable PCMCIA cards with strict input surge limits. IC Role / Device Role / Timing Role: Burst-mode DC-DC regulator; provides regulated output from variable 2.7–6V host bus supply while meeting PCMCIA inrush current spec. Use Value: Programmable LIM pin ensures compliance with PCMCIA socket current limits (<500mA) without overdesigning reservoir capacitance. |
| Industrial Telematics Modem | Portable Medical Wireless Transmitter |
Use Scenario: Enabling LTE/GSM fallback in vehicle-mounted telematics units powered by 12V battery via intermediate 3.3V rail. IC Role / Device Role / Timing Role: Secondary boost stage generating stable 5V for RF module from noisy, wide-range intermediate supply. Use Value: 3µA shutdown current and –40°C to +85°C rating ensure reliable cold-cranking operation and low standby drain in always-on tracking systems. | Use Scenario: Powering FDA-compliant 2.4GHz ISM band transmitter in handheld patient monitors with single-cell primary battery. IC Role / Device Role / Timing Role: Efficient, low-noise boost converter supplying pulsed RF load while maintaining EMI compliance during clinical use. Use Value: Standby mode eliminates switching artifacts during transmit, ensuring RF output purity meets medical EMC Class B requirements. |
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 |
|---|---|---|---|
| MAX1688ESA | Replaces LIM pin with CHG pin; uses adaptive constant-recharge-time algorithm instead of fixed voltage-controlled current limit. | Better suited for variable-input-voltage or varying-burst-current systems where reservoir recharge time must self-adjust to VOUT droop. | Select MAX1688ESA when battery voltage varies significantly across discharge curve or burst current changes dynamically; MAX1687ESA preferred for fixed, predictable GSM burst profiles. |
| TPS61040DRBT | Fixed 28V OVP, no LIM/CHG pin; 500kHz fixed-frequency PWM (not hysteretic); lower max output current (280mA continuous). | Lacks programmable burst-current limiting and GSM-optimized standby timing; not validated for 2A pulsed loads. | Use TPS61040DRBT only for non-GSM constant-load applications under 300mA; unsuitable as direct functional replacement for MAX1687ESA in burst-mode designs. |
Compared with MAX1688ESA, MAX1687ESA offers deterministic current limiting ideal for fixed GSM burst parameters, while TPS61040DRBT lacks both burst-mode control and sufficient peak current capability-making MAX1687ESA uniquely fit for Li-Ion-powered RF amplifier supply where battery current must be tightly bounded.
Availability
MAX1687ESA is available at Aetrix Electronics and suitable for GSM handset design, wireless PC card development, and industrial telematics requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for MAX1687ESA 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 portable, industrial, and communications markets.
The MAX1687ESA belongs to Maxim's GSM-optimized power-management product line, designed specifically to solve battery-current surging and RF noise coupling challenges in cellular RF front-end power delivery.
FAQ
What is the maximum output current capability of the MAX1687ESA?
The MAX1687ESA is rated to deliver up to 2W of output power-for example, 2A at 5V-under GSM burst conditions. Its peak battery current is limited to 450mA via the LIM pin, but actual output current depends on input voltage, output voltage, and efficiency. At VIN = 3.3V and VOUT = 5V, it sustains ~1.2A continuous load with >85% efficiency, verified in Typical Operating Characteristics (Figure toc03).
Can the MAX1687ESA be used with a 3.7V Li-Ion battery throughout its full discharge range?
Yes. The MAX1687ESA operates from 2.7V to 6V input, covering the entire discharge curve of a single Li-Ion cell (4.2V down to 2.7V). Its undervoltage lockout triggers at ~2.35V (min), ensuring reliable startup even at end-of-discharge. Efficiency remains above 80% at VIN = 2.7V, VOUT = 5V, and 300mA load (Figure toc03), making it suitable for full-range Li-Ion operation.
How does the LIM pin on the MAX1687ESA function, and what voltage range should be applied?
The LIM pin on the MAX1687ESA sets peak battery current using a 0–1V analog input: ILIM = VLIM × 0.86A/V – 0.06A. At VLIM = 0–0.25V, ILIM is fixed at 200mA; from 0.25V to 1V, it scales linearly to 450mA. VLIM is internally clamped to 1.25V. Common implementation uses a resistor divider from REF (1.25V) or a DAC output, as shown in Figure 6a of the datasheet.
Is the MAX1687ESA pin-compatible with the MAX1688ESA?
No. Although both share the same 8-pin SO package and most pin functions, the MAX1687ESA uses pin 8 as LIM (current-limit adjust), while the MAX1688ESA uses pin 8 as CHG (recharge-time adjust). Their control architectures differ fundamentally-voltage-controlled limit vs. adaptive recharge-and swapping them requires PCB layout changes and firmware updates to the control signal.
Does the MAX1687ESA require an external Schottky diode?
No. The MAX1687ESA integrates synchronous rectification using internal N- and P-channel MOSFETs, eliminating the need for an external Schottky diode. This improves efficiency (>90%), reduces thermal stress, and simplifies layout-confirmed in the General Description and Features sections of the datasheet.
MAX1687ESA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm 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:
- 8-SOIC
MAX1687ESA FAQ
1.How can I place an order for MAX1687ESA through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1687ESA 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 MAX1687ESA reliable?
The price and inventory of MAX1687ESA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1687ESA is usually 5 days.
3.What payment methods are accepted for MAX1687ESA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1687ESA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1687ESA?
MAX1687ESA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1687ESA 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 MAX1687ESA?
For technical support, including MAX1687ESA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1687ESA requirements.
6.How does Aetrix verify that MAX1687ESA is sourced from the original manufacturer or authorized distributors?
All MAX1687ESA 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 MAX1687ESA meets industry standards.
7.What is the process for return or replacement of MAX1687ESA?
All MAX1687ESA units undergo pre-shipment inspection (PSI). If there is an issue with MAX1687ESA, 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 MAX1687ESA part is unused and in its original packaging.
Return procedure for MAX1687ESA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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