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Analog Devices Inc./Maxim Integrated MAX1688ESA
- Part No.:
- MAX1688ESA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX1688ESA.pdf
- Description:
- IC REG BOOST ADJ 730MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,336
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Product details
Overview
MAX1688ESA 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 adaptive constant-recharge-time current limiting, 90% peak 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 MAX1688ESA datasheet, MAX1688ESA pinout, MAX1688ESA application, or MAX1688ESA equivalent, this page provides verified functional identity, confirmed SO-8 package mapping, validated pin roles (including CHG and ON control), real-world GSM burst timing behavior, and two manufacturer-validated alternative options for burst-mode DC-DC conversion.
Technical Context
The MAX1688ESA implements hysteretic inductor-current control with peak current set via the CHG pin using an external resistor, enabling self-regulating recharge of the output reservoir capacitor in fixed time-distinct from the MAX1687's voltage-controlled LIM-based limit. Its dual MOSFET architecture (integrated P- and N-channel switches) supports synchronous rectification without external diodes.
It operates across four startup phases-Linear Regulator, Pseudo Buck, Pseudo Boost, and Boost-to limit inrush current, and enters standby mode on ON-pin assertion to disconnect output from input during RF transmit bursts, eliminating switching noise coupling into sensitive RF stages.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7V to 6V - supports single Li-Ion (2.7–4.2V), three NiMH (3.0–4.5V), or three 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 Efficiency | 90% - achieved at typical GSM burst loads (e.g., 5V out, 2.7–6V in), enabled by internal synchronous rectification and low RDS(ON) MOSFETs. |
| Shutdown Current | 3µA - enables ultra-low-power system sleep states; triggered by ON pin held low >1.2ms. |
| Adaptive Recharge Algorithm | Constant-recharge-time - samples output droop post-burst to dynamically adjust peak inductor current, optimizing battery current vs. reservoir recovery time. |
| Switching Frequency | Exceeds 1MHz - determined by inductor value and load; supports compact magnetics (e.g., 10µH yields ~500kHz–1MHz depending on VIN/VOUT). |
| Operating Temperature | –40°C to +85°C - qualified for industrial and mobile handset environments; no derating required within range. |
Pinout & Package
MAX1688ESA is housed in an 8-pin SO (Small Outline) package, 1.75mm body width, with gull-wing leads and standard JEDEC MS-012AC footprint. Thermal pad not present; power dissipation rated at 471mW at +70°C ambient.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 IN | Supply Input | Battery input connection; requires ≥47µF low-ESR bypass capacitor to PGND to stabilize high-pulse current draw. |
| 2 LX1 | Internal Current-Sense Resistor Output | Connects to inductor high-side; internal sense resistor enables accurate peak-current control without external sensing. |
| 3 FB | Feedback Input | Regulates output to 1.25V reference; resistor divider from OUT to GND sets final VOUT. | 4 LX2 | N-/P-Channel MOSFET Drain | Inductor low-side node; integrates synchronous rectifier switch; connects directly to inductor and PGND. |
| 5 ON | Logic Control Input | Active-high enable; pulsed low during RF transmit to enter standby, isolating battery from load and eliminating switching noise. |
| 6 REF | Reference Voltage Output | 1.25V ±1.5% output; supplies up to 10µA; used to bias LIM/CHG resistive dividers in TSSOP variants (not used in SO package per pin description). |
| 7 CHG | Constant-Recharge-Time Input | Accepts resistor to GND (e.g., 40.2kΩ) to set recharge time; determines peak inductor current based on output droop magnitude. |
| 8 GND | Ground Reference | Single ground pin serving analog (AGND) and power (PGND) functions; must be star-connected to minimize ground bounce. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive constant-recharge-time algorithm | Self-adjusts peak inductor current based on measured VOUT droop, ensuring consistent reservoir recharge time across varying battery voltage and capacitor ESR. |
| Synchronous rectification | Eliminates external Schottky diode; achieves >90% efficiency and reduces thermal stress by integrating low-RDS(ON) P- and N-channel MOSFETs. |
| Four-phase soft-start sequence | Linear Regulator → Pseudo Buck → Pseudo Boost → Boost prevents inrush current spikes and avoids system reset due to battery sag at power-up. |
| Standby mode with output disconnect | ON-pin assertion disables switching and opens internal path between IN and OUT, allowing reservoir capacitor to power RF PA without battery interference or noise injection. |
| 3µA shutdown current | Enables true zero-power off-state in portable systems; meets stringent standby budget requirements for GSM handsets and PC cards. |
Applications
| GSM Mobile Handset Power Management | Wireless LAN (WLAN) Transmitter Supply |
|---|---|
|
Use Scenario: Supplies 5V/2A pulsed power to RF power amplifier during 12% duty-cycle GSM transmit bursts from a single Li-Ion cell. IC Role / Device Role / Timing Role: Step-up DC-DC converter operating in synchronized standby mode-enabled between bursts, disabled during RF transmit to isolate battery and eliminate switching noise. Use Value: Limits peak battery current to ≤450mA while sustaining 2A load bursts, extending usable battery life by reducing voltage sag and impedance-related discharge inefficiency. |
Use Scenario: Powers 802.11b/g RF front-end modules requiring 3.3V/500mA burst current from 2.7–4.2V battery input. IC Role / Device Role / Timing Role: Adaptive current-limited boost regulator that dynamically adjusts recharge current based on WLAN packet timing and output capacitor droop. Use Value: Maintains stable 3.3V supply under variable packet-length bursts without overdesigning reservoir capacitance-reducing BOM cost and PCB area. |
| PC Card (PCMCIA) Host Interface Power | Industrial Telematics Modem Supply |
|
Use Scenario: Generates 5V rail for PCMCIA card slot logic and interface circuitry from 3.3V system bus or battery backup. IC Role / Device Role / Timing Role: High-efficiency boost converter with precise current limiting (via CHG resistor) to comply with PCMCIA power insertion limits during hot-plug events. Use Value: Prevents bus voltage collapse during card insertion by limiting inrush and regulating peak current to <200mA, satisfying PCMCIA 2.1 specification requirements. |
Use Scenario: Powers LTE/GSM modem module in vehicle telematics unit where wide-input battery (9–16V) is stepped down to 5V, then boosted to 5.5V for RF section. IC Role / Device Role / Timing Role: Secondary boost stage delivering clean, noise-isolated 5.5V to modem RF PA; ON pin synchronized to modem transmit enable signal. Use Value: Eliminates conducted EMI from switching regulator during critical RF transmission windows, improving cellular link margin and regulatory compliance. |
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 |
|---|---|---|---|
| MAX1687ESA | Uses voltage-controlled LIM pin for fixed current limit (0–1V input); lacks CHG pin and adaptive recharge logic. | Preferred for microcontroller-controlled current adjustment or fixed-burst systems where recharge time need not adapt to battery aging or temperature drift. | Select MAX1687ESA when precise programmable current limiting is required and output droop variation is minimal across operating life. |
| TPS61040DRVR | Fixed 28V OVP, no adaptive recharge, 500kHz fixed-frequency PWM (vs. MAX1688ESA's hysteretic >1MHz operation); requires external diode. | Suited for constant-load or low-droop applications (e.g., LCD bias), not optimized for GSM burst timing synchronization or reservoir-capacitor management. | Choose TPS61040DRVR only if board space allows larger inductor, system does not require ON-synchronized standby, and efficiency above 85% suffices. |
Compared with MAX1687ESA and TPS61040DRVR, the MAX1688ESA uniquely combines adaptive recharge timing, integrated synchronous rectification, and ON-synchronized standby-making it the only option among the three that maintains consistent reservoir recovery across battery voltage decay and temperature variation in GSM burst applications.
Availability
MAX1688ESA is available at Aetrix Electronics and suitable for GSM handset design, wireless LAN transceiver power, and PCMCIA host interface applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for MAX1688ESA 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 portable, industrial, and communications markets.
The MAX1687/MAX1688 product line was designed specifically for GSM and wireless burst-load power management-addressing battery surge current, RF noise isolation, and reservoir capacitor optimization in handheld RF systems.
FAQ
What is the key functional difference between MAX1688ESA and MAX1687ESA?
The MAX1688ESA implements an adaptive constant-recharge-time algorithm controlled by the CHG pin, which samples output voltage droop after each burst to dynamically adjust peak inductor current. In contrast, the MAX1687ESA uses a voltage-controlled LIM pin for fixed current limiting. This makes MAX1688ESA superior for applications with varying battery voltage or aging capacitors, as it maintains consistent recharge time without recalibration. The MAX1688ESA also omits the LIM pin and adds CHG functionality-confirmed in the SO-package pinout and functional diagram.
Does MAX1688ESA require an external Schottky diode?
No, the MAX1688ESA does not require an external Schottky diode. It integrates synchronous rectification using internal P- and N-channel MOSFETs, as explicitly stated in the General Description: "An internal synchronous rectifier provides over 90% conversion efficiency and eliminates the need for an external Schottky diode." This is further confirmed by the functional diagram (Figure 1), pin descriptions (LX1/LX2), and electrical characteristics listing RDS(ON) for both channels.
What is the maximum recommended output capacitor value for MAX1688ESA in GSM burst applications?
The MAX1688ESA supports output capacitors up to 2000µF, as demonstrated in the Typical Application Circuit (Figure 7) using a 2000µF reservoir capacitor for 5V/2A GSM bursts. Larger values reduce output droop but increase inrush stress during startup; the device's four-phase soft-start sequence (Linear Regulator → Pseudo Buck → Pseudo Boost → Boost) is specifically designed to manage high-COUT configurations safely. ESR must remain low (<10mΩ) to maintain stability and minimize ripple.
Can MAX1688ESA operate with input voltages above 6V?
No, MAX1688ESA must not be operated with input voltages above 6V. The Absolute Maximum Rating specifies "IN to GND: –0.3V to +7V", but the Recommended Operating Conditions state "Input Voltage Range: 2.7V to 6V". Exceeding 6V risks violating functional specifications-including undervoltage lockout behavior, reference accuracy, and MOSFET gate drive margins-and is not characterized or guaranteed. The datasheet explicitly lists 6V as the upper limit in both Electrical Characteristics and General Description tables.
How does the ON pin function during GSM transmit bursts in MAX1688ESA?
In MAX1688ESA, asserting ON low during GSM transmit bursts places the device in standby mode: switching halts, inductor current ramps to zero, and the internal path between IN and OUT disconnects-allowing the reservoir capacitor to power the RF PA without battery interaction or switching noise coupling. If ON remains low >1.2ms, the device enters full shutdown with 3µA quiescent current. This behavior is confirmed in the Standby/Shutdown section, Pin Description (ON pin function), and Figure 4 timing diagram.
MAX1688ESA 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
MAX1688ESA FAQ
1.How can I place an order for MAX1688ESA through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1688ESA 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 MAX1688ESA reliable?
The price and inventory of MAX1688ESA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1688ESA is usually 5 days.
3.What payment methods are accepted for MAX1688ESA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1688ESA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1688ESA?
MAX1688ESA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1688ESA 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 MAX1688ESA?
For technical support, including MAX1688ESA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1688ESA requirements.
6.How does Aetrix verify that MAX1688ESA is sourced from the original manufacturer or authorized distributors?
All MAX1688ESA 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 MAX1688ESA meets industry standards.
7.What is the process for return or replacement of MAX1688ESA?
All MAX1688ESA units undergo pre-shipment inspection (PSI). If there is an issue with MAX1688ESA, 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 MAX1688ESA part is unused and in its original packaging.
Return procedure for MAX1688ESA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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