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MP4688DN-LF LED Driver IC Equivalent & Substitute Parts
Part Overview
The MP4688DN-LF is an active LED Driver IC manufactured by Monolithic Power Systems Inc., designed for step-down (buck) DC-DC regulation with PWM dimming capability. This single-output regulator supports 1A output current across a 4.5V to 75V input supply range and operates at 2MHz switching frequency. The device is housed in an 8-SOIC package with exposed pad and is automotive-grade, making it suitable for lighting applications requiring high input voltage tolerance and thermal management.
Substitute parts are identified to provide design flexibility when the primary part is unavailable, when alternative packaging is required for manufacturing constraints, or when different thermal or frequency characteristics better suit specific application requirements.
Substiute Parts
Key Parameters
| Parameter | MP4688DN-LF |
|---|---|
| Manufacturer | Monolithic Power Systems Inc. |
| Category | Power Management (PMIC) |
| Type | DC DC Regulator |
| Topology | Step-Down (Buck) |
| Number of Outputs | 1 |
| Voltage Supply (Min) | 4.5V |
| Voltage Supply (Max) | 75V |
| Current Output / Channel | 1A |
| Switching Frequency | 2MHz |
| Dimming | PWM |
| Operating Temperature | -40°C ~ 85°C (TA) |
| Grade | Automotive |
| Package / Case | 8-SOIC (0.154", 3.90mm Width) Exposed Pad |
| RoHS Status | ROHS3 Compliant |
| Product Status | Active |
Substitute Part Grouping Explanation
Substitution eligibility for the MP4688DN-LF is determined by the following critical parameters:
Primary Substitution Criteria:
- Topology: Step-Down (Buck) configuration
- Number of Outputs: Single output
- Dimming Capability: PWM support
- Current Rating: Minimum 1A output capability
- Input Voltage Range: Minimum 4.5V supply support
- Internal Switch: Integrated switching element
- RoHS Compliance: ROHS3 Compliant
- Product Status: Active
Secondary Compatibility Factors:
- Operating temperature range (-40°C minimum, 85°C or higher maximum)
- Package type compatibility with 8-pin or equivalent footprints
- Automotive grade preferred for consistency
Substitute parts are grouped into two categories:
Category A - Direct Functional Equivalents (Same topology, output current ≥1A, input voltage ≥4.5V): LM3404MR/NOPB, LM3414MR/NOPB, LM3406MH/NOPB, LT3474EFE#TRPBF
Category B - Functional Alternatives (Step-down topology, reduced output current or input voltage, alternative dimming methods): LM3402MRX/NOPB, LM3407MY/NOPB, AL8860WT-7, AL8861Y-13, IS31LT3352-V1GRLS2-TR
Category C - Topology Variant (Step-up topology, not recommended for direct substitution): AP5725WG-7
Parameter Comparison
| Part Number | Manufacturer | Topology | Output Current | Input Voltage (Min) | Input Voltage (Max) | Frequency | Dimming | Package | Operating Temp | Grade | Product Status |
|---|---|---|---|---|---|---|---|---|---|---|---|
| MP4688DN-LF | MPS | Step-Down (Buck) | 1A | 4.5V | 75V | 2MHz | PWM | 8-SOIC Exposed Pad | -40°C ~ 85°C | Automotive | Active |
| LM3404MR/NOPB | Texas Instruments | Step-Down (Buck) | 1A | 6V | 42V | 1MHz | PWM | 8-PowerSOIC Exposed Pad | -40°C ~ 125°C | Automotive | Active |
| LM3414MR/NOPB | Texas Instruments | Step-Down (Buck) | 1A | 4.5V | 42V | 500kHz | Analog, PWM | 8-PowerSOIC Exposed Pad | -40°C ~ 125°C | Automotive | Active |
| LM3406MH/NOPB | Texas Instruments | Step-Down (Buck) | 1.5A | 6V | 42V | 10kHz ~ 1MHz | PWM | 14-PowerTSSOP | -40°C ~ 125°C | Automotive | Active |
| LM3407MY/NOPB | Texas Instruments | Step-Down (Buck) | 350mA | 4.5V | 30V | 300kHz ~ 1MHz | PWM | 8-HVSSOP | -40°C ~ 125°C | Standard | Active |
| LM3402MRX/NOPB | Texas Instruments | Step-Down (Buck) | 500mA | 6V | 42V | 1MHz | PWM | 8-PowerSOIC Exposed Pad | -40°C ~ 125°C | Standard | Active |
| LT3474EFE#TRPBF | Analog Devices Inc. | Step-Down (Buck) | 1A | 4.6V | 36V | 200kHz ~ 2MHz | PWM | 16-TSSOP Exposed Pad | -40°C ~ 85°C | Automotive | Active |
| AL8860WT-7 | Diodes Incorporated | Step-Down (Buck) | 1A | 4.5V | 40V | 1MHz | Analog, PWM | SOT-23-5 | -40°C ~ 105°C | Standard | Active |
| AL8861Y-13 | Diodes Incorporated | Step-Down (Buck) | 1.5A | 4.5V | 40V | 1MHz | Analog, PWM | SOT-89-5 | -40°C ~ 85°C | Standard | Active |
| IS31LT3352-V1GRLS2-TR | Lumissil Microsystems | Step-Down (Buck) | 750mA | 6V | 40V | 1MHz | Analog, PWM | 8-SOP | -40°C ~ 85°C | Standard | Active |
| AP5725WG-7 | Diodes Incorporated | Step-Up (Boost) | 750mA (Switch) | 2.7V | 5.5V | 1.2MHz | PWM | SOT-23-6 | -40°C ~ 85°C | Standard | Active |
Engineering Selection Recommendations
Recommended Direct Substitutes (Highest Compatibility):
LM3404MR/NOPB and LM3414MR/NOPB are the primary alternatives. Both are automotive-grade, active-status devices with 1A output current and step-down topology. LM3404MR/NOPB operates at 1MHz with a maximum input of 42V, while LM3414MR/NOPB supports 4.5V minimum input (matching MP4688DN-LF) with dual dimming modes (Analog and PWM). Both devices feature extended operating temperature to 125°C and are ROHS3 compliant.
LM3406MH/NOPB provides 1.5A output current in a 14-pin package with automotive grade and 125°C maximum temperature rating. This device is suitable when higher current capacity is required.
LT3474EFE#TRPBF is automotive-grade with 1A output, 2MHz frequency matching, and PWM dimming. It operates from 4.6V minimum input and supports up to 36V, with a 16-pin TSSOP package. Operating temperature extends to 85°C, matching the MP4688DN-LF specification.
Alternative Substitutes (Functional Compatibility with Limitations):
AL8860WT-7 and AL8861Y-13 (Diodes Incorporated) are step-down regulators with PWM and analog dimming support. AL8860WT-7 provides 1A output in a compact SOT-23-5 package with 105°C maximum temperature. AL8861Y-13 offers 1.5A output in SOT-89-5 package. Both support 4.5V minimum input but are limited to 40V maximum input and lack automotive grade.
LM3407MY/NOPB is a lower-current alternative (350mA) suitable for reduced-power lighting applications. It supports 4.5V minimum input with extended temperature range to 125°C but is not automotive-grade.
IS31LT3352-V1GRLS2-TR provides 750mA output with dual dimming modes in an 8-SOP package. Minimum input is 6V, limiting compatibility with lower supply voltages.
Not Recommended:
AP5725WG-7 uses step-up (boost) topology, fundamentally different from the MP4688DN-LF step-down architecture. This device is unsuitable for direct substitution despite PWM dimming capability.
Frequently Asked Questions (FAQ)
Q: Can LM3407MY/NOPB replace MP4688DN-LF in all applications?
A: LM3407MY/NOPB is functionally compatible for PWM dimming LED driver applications but has reduced output current (350mA vs. 1A). It is suitable only for lower-power lighting designs. The device lacks automotive grade certification, which may be a constraint for automotive lighting applications.
Q: What is the key difference between LM3414MR/NOPB and LM3404MR/NOPB?
A: Both are automotive-grade, 1A step-down regulators. LM3414MR/NOPB supports 4.5V minimum input (matching MP4688DN-LF) and offers dual dimming modes (Analog and PWM) at 500kHz frequency. LM3404MR/NOPB requires 6V minimum input and operates at 1MHz with PWM-only dimming. LM3414MR/NOPB is preferred when lower input voltage support is required.
Q: Why is AP5725WG-7 listed if it cannot substitute MP4688DN-LF?
A: AP5725WG-7 is included for reference as a step-up (boost) topology alternative for applications requiring voltage elevation rather than regulation. It is not a functional substitute for step-down buck regulation.
Q: Are Diodes Incorporated parts (AL8860WT-7, AL8861Y-13) suitable for automotive applications?
A: Both AL8860WT-7 and AL8861Y-13 are active-status, ROHS3-compliant devices with PWM and analog dimming support. However, neither carries automotive grade certification. They are suitable for industrial and consumer lighting applications but may not meet automotive qualification requirements.
Q: What packaging considerations apply when selecting a substitute?
A: MP4688DN-LF uses 8-SOIC with exposed pad. Direct pin-compatible alternatives include LM3404MR/NOPB and LM3414MR/NOPB (8-PowerSOIC). LM3406MH/NOPB uses 14-pin TSSOP, requiring PCB layout redesign. AL8860WT-7 uses SOT-23-5 (5-pin), and AL8861Y-13 uses SOT-89-5 (5-pin), both requiring significant layout changes. LT3474EFE#TRPBF uses 16-pin TSSOP. Package selection impacts thermal management and board space.
Q: Can I use LM3406MH/NOPB if I need higher current capacity?
A: Yes. LM3406MH/NOPB provides 1.5A output current (vs. 1A for MP4688DN-LF) in a 14-pin TSSOP package. It is automotive-grade with PWM dimming and operates to 125°C. The larger package and pin count require PCB redesign but offer improved thermal performance and higher current handling.
Q: What is the significance of the 2MHz switching frequency in MP4688DN-LF?
A: The 2MHz frequency enables smaller external component values (inductors and capacitors) compared to lower-frequency designs, reducing board space and cost. LT3474EFE#TRPBF matches this frequency range (200kHz ~ 2MHz). Most alternatives operate at 1MHz or lower, requiring larger passive components. Frequency selection depends on application size and efficiency requirements.
Q: Are all substitute parts ROHS3 compliant?
A: Yes. All listed substitute parts are ROHS3 compliant and active-status products, meeting current environmental and regulatory requirements.
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