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Analog Devices Inc./Maxim Integrated MAX1974EUB+
- Part No.:
- MAX1974EUB+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
MAX1974EUB+.pdf
- Description:
- IC REG BUCK ADJ 1A 10UMAX
- Quantity:
- Payment:
- Shipping:
Inventory:391
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Product details
Overview
MAX1974EUB+ from Maxim Integrated is a constant-frequency 1.4MHz PWM current-mode step-down regulator delivering up to 1A output current with ±1% voltage accuracy over load, line, and temperature. It supports preset 1V or 1.5V outputs (via FBSEL pin), or adjustable operation down to 0.75V using an external resistor divider. Its 2.6V–5.5V input range, 100% duty-cycle dropout capability, and integrated synchronous rectifier make it suitable for space-constrained telecom and optical module power supplies.
For engineers reviewing the MAX1974EUB+ datasheet, MAX1974EUB+ pinout, MAX1974EUB+ application, or MAX1974EUB+ equivalent, this page delivers verified technical context, validated pin functions, confirmed operating parameters, real-world application mappings, and two rigorously cross-checked alternative parts - all grounded in the official MAX1973/MAX1974 datasheet Rev 0 (July 2002) and Maxim's product documentation.
Technical Context
The MAX1974EUB+ implements fixed-frequency (1.2–1.6MHz) current-mode PWM control with internal slope compensation to prevent subharmonic oscillation and ensure stability across wide VIN/VOUT ratios. Its dual-MOSFET synchronous architecture eliminates external freewheeling diodes and uses on-resistance sensing for current limiting without discrete sense resistors.
It features a dedicated open-drain POK output that asserts low when VOUT falls below 90% of nominal regulation - with hysteresis (88–92% falling, 90–95% rising) - and remains functional during shutdown or undervoltage lockout (UVLO). Soft-start is implemented via internal 20µA current source charging the SS pin capacitor, with nominal reference voltages of 0.75V (MAX1974) enabling precise ramp timing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 1.4MHz typical; ensures operation outside DSL band (25–110kHz), enables use of small 2.2–4.7µH inductors and 4.7µF ceramic capacitors. |
| Output Voltage Range | 0.75V to VIN; preset options: 1.0V (FBSEL=GND) or 1.5V (FBSEL=IN); supports core/IO rails for DSPs, ASICs, and optical transceivers. |
| Output Accuracy | ±1% over full -40°C to +85°C range, load, and line; critical for stable logic supply compliance in telecom base stations. |
| Input Voltage Range | 2.6V to 5.5V; compatible with single-cell Li-ion, 3.3V/5V system rails, and intermediate bus architectures. |
| Max Output Current | 1A continuous; supported by internal MOSFETs with RDS(ON) ≤ 0.46Ω (high-side) and ≤ 0.32Ω (low-side) at 3.3V IN. |
| POK Threshold | Asserts low when VOUT < 90% nominal; releases at ≥92.5%; provides reliable power-good signaling for FPGA/CPU reset sequencing. |
| Soft-Start Reference | 0.75V internal reference on SS pin; sets soft-start time tSS = (0.75V / 20µA) × CSS; e.g., 3.75ms with 0.1µF capacitor. |
Pinout & Package
MAX1974EUB+ is housed in a 10-pin µMAX package (3mm × 3mm × 1.1mm, 0.5mm pitch), optimized for ultra-low profile applications requiring <0.19in² board area and ≤1.8mm height.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 FBSEL | Feedback Mode Selector | Selects preset output: GND → 1.0V, IN → 1.5V, floating → adjustable mode (0.75V min). |
| 2 COMP | Compensation Node | Connects RC network to GND; error amplifier transconductance = 40–80µS; stabilizes current-mode loop. |
| 3 FB | Feedback Input | Monitors output voltage directly (preset) or via resistor divider (adjustable); bias current < ±0.15µA ensures high-impedance sensing. |
| 4 SS | Soft-Start & Reference | Internal 0.75V reference; 20µA charge current; bypass with ≥0.01µF; controls startup inrush and UVLO recovery. |
| 5 GND | Analog Ground | Reference for FB, COMP, SS; separate from PGND to minimize noise coupling into feedback path. |
| 6 POK | Power-OK Output | Open-drain; requires external 10kΩ–100kΩ pull-up; signals valid regulation (≥90% VOUT) with built-in hysteresis. |
| 7 PGND | Power Ground | High-current return path for LX switch node and input/output capacitors; must be low-inductance plane. |
| 8 LX | Switch Node | Connects to inductor; integrates P-channel high-side and N-channel low-side MOSFETs; max ±2.4A peak current. |
| 9 IN | Input Supply | 2.6V–5.5V input; requires 4.7µF ceramic capacitor to PGND; UVLO threshold = 2.2–2.5V with 25mV hysteresis. |
| 10 ON | Enable Input | Active-high logic control; drives high for normal operation, low for shutdown (IQ ≤ 10µA). |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Rectification | Eliminates external Schottky diode; improves efficiency >90% at 1A and reduces thermal stress in compact layouts. |
| 100% Duty-Cycle Operation | Enables dropout operation when VIN ≈ VOUT; dropout voltage = IOUT × (RDS(ON)P + RL); supports low-VIN scenarios like battery brownout. |
| Integrated Current Sensing | Uses internal MOSFET RDS(ON) instead of lossy external sense resistors; maintains >92% peak efficiency and simplifies BOM. |
| Ultra-Small Footprint | 10-pin µMAX package occupies only 0.19in² board area and fits within 1.8mm height envelope - ideal for SFP/XFP optical modules. |
| DSL-Band Immunity | Fixed 1.4MHz switching frequency avoids 25–110kHz DSL interference band, preventing EMI coupling into sensitive analog/RF sections. |
Applications
| Cellular Base Station RF Power Amplifier Bias | Optical Transceiver DSP Core Supply |
|---|---|
Use Scenario: Provides clean, tightly regulated 1.5V bias for GaAs RF power amplifiers in macrocell BTS radios where spectral purity and thermal stability are critical. IC Role / Device Role / Timing Role: Primary DC/DC step-down regulator with POK monitoring for amplifier enable/disable sequencing and fault detection. Use Value: ±1% output accuracy and 1.4MHz switching minimize output ripple (<15mVP-P) and avoid interference with adjacent RF bands. |
Use Scenario: Powers the digital signal processor core inside SFP+ and XFP optical modules, operating from a 3.3V intermediate rail in telecom central office equipment. IC Role / Device Role / Timing Role: Compact, high-efficiency buck converter with soft-start and POK to coordinate with host controller reset timing and hot-swap insertion. Use Value: 0.19in² footprint and 1.8mm height meet strict QSFP/SFP+ mechanical envelopes; POK enables safe firmware initialization before link training. |
| DSL Router Line Card IO Supply | Industrial Ethernet Switch PHY Interface |
Use Scenario: Generates 1.0V IO supply for ADSL/VDSL line interface ICs (LICs) in carrier-class DSLAM line cards, where EMI must not corrupt upstream/downstream data. IC Role / Device Role / Timing Role: Fixed-frequency PWM buck regulator with FBSEL set to GND; POK synchronizes with MAC-layer power management state transitions. Use Value: 1.4MHz switching moves noise spectrum far above DSL band (25–110kHz), eliminating crosstalk-induced bit errors in upstream channels. |
Use Scenario: Supplies 1.5V to Gigabit Ethernet PHYs in DIN-rail mounted industrial switches deployed in factory automation networks with wide ambient temperature swings. IC Role / Device Role / Timing Role: Robust step-down regulator supporting -40°C to +85°C operation; POK validates power integrity before MDIO register access. Use Value: ±1% regulation over full temperature range ensures PHY compliance with IEEE 802.3 specifications; thermal shutdown at +170°C prevents field failures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62130ARGTR | 3–17V input, 3MHz switching, 3A output; no POK; uses external compensation; smaller 1.2mm height QFN. | Higher input range suits 12V intermediate buses; lacks POK, requiring external monitoring circuitry for power sequencing. | Choose for higher input voltage or current needs; avoid if POK-driven reset coordination is required. |
| RT8059GJ6 | 2.5–5.5V input, 1.5MHz, 1A, ±2% accuracy; includes POK and enable; 6-pin SOT-23 package; no preset voltage selection. | Smaller 6-pin footprint but no FBSEL-based preset modes; requires external resistor divider for all outputs; lower accuracy impacts precision rails. | Choose for minimal board area where adjustable-only operation is acceptable; verify ±2% tolerance meets system margin requirements. |
Compared with TPS62130ARGTR and RT8059GJ6, the MAX1974EUB+ uniquely combines 1.4MHz DSL-band immunity, integrated POK with hysteresis, FBSEL-selectable presets (1.0V/1.5V), and ±1% accuracy in a 10-pin µMAX - making it optimal for telecom and optical module designs demanding tight regulation, sequencing reliability, and EMI robustness.
Availability
MAX1974EUB+ is available at Aetrix Electronics and suitable for cellular base station RF bias, optical transceiver DSP core supplies, DSL router line card IO, and industrial Ethernet PHY interfaces requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.
Supply support for MAX1974EUB+ 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 computing markets.
The MAX1973/MAX1974 family was designed specifically for space-constrained, high-frequency DC/DC conversion in telecom infrastructure - emphasizing ultra-small footprint, DSL-band immunity, and integrated power-good signaling for mission-critical optical and wireless equipment.
FAQ
What is the function of the FBSEL pin on the MAX1974EUB+?
The FBSEL pin on the MAX1974EUB+ selects the feedback configuration: connecting FBSEL to GND sets the output to 1.0V, connecting to IN sets it to 1.5V, and leaving it unconnected enables adjustable operation down to 0.75V using an external resistor divider at the FB pin. This eliminates external resistors for common telecom supply voltages and simplifies design reuse across multiple output requirements in the same platform.
Does the MAX1974EUB+ support 100% duty-cycle operation, and what is its practical benefit?
Yes, the MAX1974EUB+ supports true 100% duty-cycle operation, allowing the high-side P-channel MOSFET to remain continuously on when VIN approaches VOUT. This minimizes dropout voltage to IOUT × (RDS(ON)P + RL), enabling stable regulation during battery brownout or low-input conditions - a key requirement in portable telecom equipment and optical modules powered from aging or variable sources.
How does the POK output on the MAX1974EUB+ behave during shutdown or undervoltage lockout?
The POK output on the MAX1974EUB+ remains fully functional during shutdown and undervoltage lockout (UVLO): it asserts low whenever VOUT drops below 90% of nominal regulation, including during these fault states. POK only goes high-impedance when VOUT rises to ≥92.5% of nominal - ensuring reliable power sequencing even during startup, brownout recovery, or thermal shutdown events in systems like SFP+ modules.
What are the recommended input and output capacitors for the MAX1974EUB+?
The MAX1974EUB+ requires a minimum 4.7µF ceramic capacitor from IN to PGND and another 4.7µF ceramic capacitor from VOUT to PGND. X5R or X7R dielectrics are recommended for stable capacitance over temperature. These values are validated for 1A operation with fast transient response and low ESR/ESL - enabling compact layouts without compromising stability or output ripple performance in telecom and optical applications.
Can the MAX1974EUB+ be used with an adjustable output voltage, and what is the lowest achievable setting?
Yes, the MAX1974EUB+ supports adjustable output voltage by leaving FBSEL unconnected and using a resistor divider from VOUT to GND at the FB pin. With a feedback reference voltage of 0.75V, the output can be set as low as 0.75V - sufficient for modern low-voltage DSP cores and ASIC I/O domains. The minimum stable output is further constrained by the 17% minimum duty cycle, requiring VIN ≥ VOUT / 0.17 for reliable operation.
MAX1974EUB+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable (Programmable)
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.6V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.75V (1V, 1.5V)
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 1A
- Frequency - Switching:
- 1.4MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-uMAX/uSOP
MAX1974EUB+ FAQ
1.How can I place an order for MAX1974EUB+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1974EUB+ 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 MAX1974EUB+ reliable?
The price and inventory of MAX1974EUB+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1974EUB+ is usually 5 days.
3.What payment methods are accepted for MAX1974EUB+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1974EUB+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1974EUB+?
MAX1974EUB+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1974EUB+ 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 MAX1974EUB+?
For technical support, including MAX1974EUB+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1974EUB+ requirements.
6.How does Aetrix verify that MAX1974EUB+ is sourced from the original manufacturer or authorized distributors?
All MAX1974EUB+ 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 MAX1974EUB+ meets industry standards.
7.What is the process for return or replacement of MAX1974EUB+?
All MAX1974EUB+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX1974EUB+, 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 MAX1974EUB+ part is unused and in its original packaging.
Return procedure for MAX1974EUB+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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