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Analog Devices Inc./Maxim Integrated MAX1557ETB+T
- Part No.:
- MAX1557ETB+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
MAX1557ETB+T.pdf
- Description:
- IC REG BUCK ADJ 600MA 10TDFN
- Quantity:
- Payment:
- Shipping:
Inventory:6,163
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Product details
Overview
MAX1557ETB+T from Maxim Integrated is a 600mA synchronous step-down DC-DC converter optimized for single-cell Li-ion or 3-cell alkaline/NiMH battery-powered portable devices. It delivers pin-selectable 1.0V, 1.3V, or 1.5V outputs (or adjustable down to 0.75V), operates from 2.6V–5.5V input, and achieves up to 97% efficiency at full load with only 16µA quiescent current.
For engineers reviewing the MAX1557ETB+T datasheet, MAX1557ETB+T pinout, MAX1557ETB+T application, or MAX1557ETB+T equivalent, this page provides verified technical context, validated pin functions, confirmed output voltage selection logic, real-world load-transient performance data, and two rigorously cross-checked alternative parts for low-power portable power management designs.
Technical Context
The MAX1557ETB+T uses a fixed-frequency (1MHz) current-mode PWM control architecture with internal slope compensation and auto pulse-skipping at light loads to maintain 16µA quiescent current. Its proprietary topology enables high efficiency across 1mA–600mA load range without external compensation.
It integrates a low-RDS(ON) p-channel high-side switch (0.42Ω typ at 2.6V) and n-channel synchronous rectifier, supports 100% duty-cycle dropout operation with only 27µA quiescent current in dropout, and implements voltage positioning for minimized load-transient overshoot/undershoot-achieving ≤±0.75% output deviation at 300mA load per Electrical Characteristics table.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 600mA guaranteed continuous output - sufficient for core logic rails in PDAs, MP3 players, and handheld instruments. |
| Input Voltage Range | 2.6V to 5.5V - compatible with fully discharged 3-cell alkaline (≈3.0V) and charged single-cell Li-ion (4.2V). |
| Quiescent Current | 16µA typical - extends battery life in standby mode of always-on portable devices. |
| Switching Frequency | 1MHz ±10% - enables use of tiny 3.3µH–4.7µH inductors and compact ceramic capacitors. |
| Output Voltage Options | Pin-selectable 1.0V, 1.3V, 1.5V, or adjustable (0.75V to VIN) - matches low-voltage microcontroller I/O and core supply requirements. |
| Dropout Quiescent Current | 27µA typical - maintains ultra-low power draw when input drops near output voltage, maximizing usable battery capacity. |
| Shutdown Current | 0.1µA - enables true zero-power disable in battery-critical systems. |
Pinout & Package
Tiny 10-pin TDFN-EP package (3mm × 3mm, 0.8mm height) with exposed paddle for thermal dissipation. RoHS-compliant, lead-free, moisture-sensitive level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 IN | Low-current input supply | Connects to 2.6V–5.5V source; bypassed via RC filter in MAX1556 designs but directly tied to INP for MAX1557ETB+T. |
| 2 GND | Analog ground reference | Must be star-connected to PGND at output capacitor; ties to exposed paddle for thermal and electrical integrity. |
| 3 SS | Soft-start timing control | Requires 1000pF capacitor to GND to eliminate input-current overshoot during startup; internally discharged via 200Ω in shutdown. |
| 4 OUT | Feedback sense node | Connects directly to regulated output; internal resistor-divider remains active in shutdown for preset voltages. |
| 5 SHDN | Logic-controlled enable/disable | Drive low to enter 0.1µA shutdown; drive high or tie to IN for normal operation. |
| 6 D2 | Output voltage select bit | Binary input (0=GND, 1=IN) - combined with D1 determines 1.0V/1.3V/1.5V/adjustable per Table 1. |
| 7 PGND | Power ground return | High-current return path for LX switch and output capacitor; must be low-inductance connection to GND plane. |
| 8 LX | Switch-node connection | Drain node of internal p-channel and n-channel MOSFETs; connects to inductor; high-impedance in shutdown. |
| 9 INP | High-current input supply | Main power path - bypass with 10µF ceramic capacitor to PGND; tied directly to IN in MAX1557 applications. |
| 10 D1 | Output voltage select bit | Binary input (0=GND, 1=IN) - pairs with D2 to configure output voltage without external resistors. |
Key Features
| Feature | Design Value |
|---|---|
| Voltage positioning load regulation | Enables ≤±0.75% output deviation at 300mA load while eliminating transient droop - critical for CPU and DSP core supplies. |
| Synchronous rectification | Eliminates need for external Schottky diode, reducing BOM count and improving efficiency by >5% vs. asynchronous designs. |
| 1MHz PWM switching | Permits use of sub-5mm footprint inductors (e.g., 3.3µH/4.7µH) and 22µF X5R ceramic output capacitors - saves PCB area in space-constrained devices. |
| Adjustable soft-start | Configurable ramp time (via CSS) prevents input surge current - protects weak battery sources like alkaline cells during power-up. |
| 100% duty-cycle dropout | Maintains regulation as input decays to within ~100mV of output (e.g., 3.3V→3.2V), extending runtime by utilizing full battery discharge curve. |
Applications
| PDA & Palmtop Power Rail | Smartphone Baseband Core |
|---|---|
Use Scenario: Powering ARM9-based PDA main processor core at 1.3V from 3.7V Li-ion battery. IC Role / Device Role / Timing Role: Primary synchronous buck regulator delivering stable 1.3V/600mA with voltage positioning to suppress load transients during CPU burst activity. Use Value: Eliminates 5% undershoot during 0→600mA load steps (per toc13/toc14), maintaining core voltage within spec across full battery discharge (2.6V–4.2V). |
Use Scenario: Supplying 1.0V core rail to baseband IC in GSM smartphone with tight battery-life targets. IC Role / Device Role / Timing Role: Low-IQ step-down converter enabling 16µA sleep-mode current while supporting fast wake-up with analog soft-start. Use Value: Extends standby time by 30% vs. comparable 50µA-IQ regulators, validated at -40°C to +85°C operating range. |
| Digital Camera Image Sensor Bias | Handheld Test Instrument ADC Reference |
Use Scenario: Generating clean 1.5V bias for CMOS image sensor analog front-end in compact digital camera. IC Role / Device Role / Timing Role: Low-noise, low-ripple DC-DC source with <10mVpp output ripple (22µF COUT, 1MHz switching) and minimal EMI coupling to sensitive analog circuitry. Use Value: Achieves <65dB PSRR at 100kHz (per BODE PLOT toc16), preventing switching noise from degrading image SNR. |
Use Scenario: Providing precision 1.0V reference supply for 16-bit SAR ADC in battery-operated handheld multimeter. IC Role / Device Role / Timing Role: High-accuracy, low-drift regulator with ±0.75% output tolerance over temperature and line/load - referenced to internal 0.75V FB threshold. Use Value: Maintains ADC reference stability within ±1 LSB error across 0–600mA load and 2.6V–5.5V input, eliminating calibration drift. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down DC-DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62231DRYR | 600mA, 1.0V–3.3V adjustable, 20µA IQ, 3.5MHz switching, 6-pin WSON | Higher frequency enables smaller inductors but increases EMI sensitivity; lacks voltage positioning and pin-selectable outputs. | Prefer when board space is constrained and external feedback is acceptable; avoid where load-transient immunity is critical. |
| RT8059GJ6 | 600mA, 1.0V–3.3V adjustable, 25µA IQ, 1.5MHz, 6-pin TSOT-23 | No pin-selectable outputs; requires external resistors for all voltages; no voltage positioning; higher dropout voltage. | Acceptable for cost-sensitive designs with simple fixed-output needs; not suitable for battery-discharge optimization or transient-critical loads. |
Compared with TPS62231DRYR and RT8059GJ6, the MAX1557ETB+T uniquely combines pin-selectable low-voltage outputs, voltage positioning for zero-droop load transients, and 27µA dropout IQ - making it the only option among the three that fully supports deep-battery-discharge operation in portable instrumentation and imaging systems.
Availability
MAX1557ETB+T is available at Aetrix Electronics and suitable for PDA power rails, smartphone baseband cores, digital camera sensor bias, and handheld test instrument ADC references requiring stable component supply across industrial temperature range (-40°C to +85°C) and long-term production continuity.
Supply support for MAX1557ETB+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 demanding industrial, automotive, and portable applications.
The MAX1557ETB+T belongs to Maxim's ultra-low-IQ synchronous buck converter product line, designed specifically to maximize battery runtime in space-constrained portable electronics while maintaining tight regulation under dynamic load conditions.
FAQ
What output voltages does the MAX1557ETB+T support without external resistors?
The MAX1557ETB+T supports three fixed output voltages-1.0V, 1.3V, and 1.5V-selected solely by tying pins D1 and D2 to GND or IN per the truth table in the datasheet. When both D1 and D2 are grounded, the device enters adjustable mode (0.75V to VIN) requiring external feedback resistors. No other preset voltages (e.g., 1.8V or 2.5V) are supported by the MAX1557ETB+T; those are exclusive to the MAX1556 family.
How does the MAX1557ETB+T achieve low quiescent current during light-load operation?
The MAX1557ETB+T automatically enters pulse-skipping mode below ~10mA load, disabling the PWM comparator and reducing switching activity while maintaining regulation. This design yields a typical quiescent current of 16µA across the full input range (2.6V–5.5V) and temperature range (−40°C to +85°C), as confirmed in the Electrical Characteristics table. In dropout (100% duty cycle), quiescent current rises only to 27µA - a key advantage for extending battery life in deeply discharged states.
What is the recommended inductor value and saturation current for the MAX1557ETB+T?
Maxim specifies a 4.7µH shielded inductor with ≥800mA saturation current for the MAX1557ETB+T at 600mA full load. Recommended parts include Taiyo Yuden LMNP04SB4R7N (4.7µH, 1200mA ISAT, 50mΩ DCR) and Sumida CDRH3D16 (4.7µH, 1200mA ISAT, 50mΩ DCR). Using a 3.3µH inductor (as for MAX1556) is not recommended - it risks peak inductor current exceeding safe limits and reduces efficiency at 600mA.
Does the MAX1557ETB+T require separate input filtering between IN and INP?
No. Unlike the MAX1556/MAX1556A, the MAX1557ETB+T requires IN to be directly connected to INP with no intervening RC filter. The datasheet explicitly states "In all MAX1557 applications, connect INP directly to IN" and confirms that no additional bypass capacitor is needed at IN. Input filtering is handled solely by the 10µF ceramic capacitor placed between INP and PGND.
What is the function of the SS pin on the MAX1557ETB+T, and what capacitor value is required?
The SS (soft-start) pin on the MAX1557ETB+T controls startup inrush current by exponentially ramping the output voltage. A 1000pF capacitor from SS to GND is required for standard operation with ≤22µF output capacitance. For larger COUT, the datasheet specifies scaling CSS as COUT/22,000 (e.g., 2200pF for 47µF COUT). The SS pin is internally discharged through 200Ω to GND during shutdown, ensuring controlled restart behavior.
MAX1557ETB+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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, 1.3V, 1.5V)
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 600mA
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-TDFN (3x3)
MAX1557ETB+T FAQ
1.How can I place an order for MAX1557ETB+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1557ETB+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 MAX1557ETB+T reliable?
The price and inventory of MAX1557ETB+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1557ETB+T is usually 5 days.
3.What payment methods are accepted for MAX1557ETB+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1557ETB+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1557ETB+T?
MAX1557ETB+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1557ETB+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 MAX1557ETB+T?
For technical support, including MAX1557ETB+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1557ETB+T requirements.
6.How does Aetrix verify that MAX1557ETB+T is sourced from the original manufacturer or authorized distributors?
All MAX1557ETB+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 MAX1557ETB+T meets industry standards.
7.What is the process for return or replacement of MAX1557ETB+T?
All MAX1557ETB+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX1557ETB+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 MAX1557ETB+T part is unused and in its original packaging.
Return procedure for MAX1557ETB+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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