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Diodes Incorporated AP1538SG-13
- Part No.:
- AP1538SG-13
- Manufacturer:
- Diodes Incorporated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AP1538SG-13.pdf
- Description:
- IC REG BUCK ADJ 3A 8SOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,618
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Product details
Overview
AP1538SG-13 from Diodes Incorporated is a synchronous step-down DC/DC converter IC with integrated P-channel MOSFET, operating from 3.6V to 18V input and delivering up to 3A output current at adjustable voltages down to 0.8V. It features 300kHz fixed-frequency PWM control, internal soft-start, over-current and short-circuit protection with foldback to 50kHz, and thermal shutdown. Used in PC motherboard VRMs and LCD monitor power rails.
For engineers reviewing the AP1538SG-13 datasheet, AP1538SG-13 pinout, AP1538SG-13 application, or AP1538SG-13 equivalent, key selection criteria include its internal PMOS RDS(ON) (70mΩ @ 12V), feedback reference voltage (0.8V ±2%), enable logic thresholds (VIH = 2.0V, VIL = 0.8V), and SOP-8L package thermal resistance (θJC = 24°C/W).
Technical Context
The AP1538SG-13 implements a constant-frequency PWM-controlled buck regulator with an internal 70mΩ P-channel high-side switch and error amplifier referenced to a 0.8V precision bandgap. Its oscillator operates at 300kHz typical, with automatic frequency reduction to 50kHz during over-current or short-circuit events.
It integrates soft-start via internal ramp generation, current limit set by external ROCSET resistor (90µA sink), and under-voltage lockout that disables operation below 3.3V VCC. The feedback loop uses resistive divider sensing and supports compensation via external capacitor on FB pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 18V - Supports AC adapter inputs and wide-input industrial rails without pre-regulation. |
| Output Voltage Range | 0.8V to VCC - Adjustable via external resistor divider; 0.8V reference enables core supply for modern microprocessors. |
| Max Output Current | 3A - Sustained delivery with thermal shutdown activation above +150°C junction temperature. |
| Switching Frequency | 300kHz typical - Enables use of compact 22µH inductors while maintaining EMI manageability. |
| Feedback Reference | 0.8V ±2% - Tight tolerance ensures accurate output regulation across line/load/temperature. |
| RDS(ON) (High-Side PMOS) | 70mΩ @ VCC = 12V - Low conduction loss improves efficiency to 92% at 5V/3A output. |
| Enable Thresholds | VIH = 2.0V, VIL = 0.8V - Compatible with standard 3.3V/5V logic control without level-shifting. |
Pinout & Package
SOP-8L package with dual exposed pads (SOP-8L-DEP variant available); 4.9mm × 6.0mm body, 1.27mm pitch, 24°C/W junction-to-case thermal resistance. Exposed pad 1 connects to VSS, exposed pad 2 connects to Output - requires isolation in PCB layout to prevent shorting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pin 1) | Feedback input | Monitors output voltage via resistive divider; 0.1µA bias current minimizes divider loading error. |
| EN (Pin 2) | Enable control | Active-high logic input; <10µA shutdown current enables low-power standby mode. |
| OCSET (Pin 3) | Current limit setting | 90µA internal sink current sets over-current threshold via external ROCSET resistor. |
| VCC (Pin 4) | Bias supply | Internal LDO output powers control circuitry; decoupling capacitor required for stability. |
| Output (Pin 5 & 6) | Switch node | High-current drain connection for external inductor/diode; dual pins reduce trace inductance and EMI. |
| VSS (Pin 7 & 8) | Power ground | Dual GND pins provide low-impedance return path; internally tied to exposed pad 1 for thermal conduction. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated P-channel MOSFET | Eliminates need for external high-side switch; reduces BOM count and layout complexity. |
| Internal compensation network | Reduces external components to only FB divider, input/output capacitors, inductor, and diode. |
| Soft-start function | Prevents output overshoot during power-up by gradually increasing duty cycle from 0%. |
| Foldback frequency during fault | Switches from 300kHz to 50kHz during OCP/SCP to reduce power dissipation and improve fault recovery. |
| Thermal shutdown with hysteresis | Triggers at +150°C with +55°C hysteresis to prevent oscillation near trip point. |
Applications
| PC Motherboard VRM | LCD Monitor Power Supply |
|---|---|
|
Use Scenario: Regulating 12V rail to 3.3V/5V for chipset I/O and display interface circuits. IC Role / Device Role / Timing Role: Primary buck controller managing transient load steps up to 3A with <1% load regulation. Use Value: Internal 70mΩ PMOS and 300kHz switching enable compact, high-efficiency design meeting Intel VRD specifications. |
Use Scenario: Generating stable 5V/3A supply for LCD panel backlight drivers and timing controllers. IC Role / Device Role / Timing Role: Main DC/DC converter delivering low-noise, ripple-controlled output for analog video signal integrity. Use Value: 0.8V reference accuracy and 0.2% load regulation ensure consistent brightness and color fidelity across varying panel loads. |
| Graphics Card Auxiliary Rail | ADSL Modem Power Management |
|
Use Scenario: Providing dedicated 1.2V/2.5A supply for GPU memory interface circuitry. IC Role / Device Role / Timing Role: Secondary buck regulator supporting fast transient response during GPU clock scaling events. Use Value: Soft-start and 99% max duty cycle allow seamless transition from low-power idle to full-load operation without rail collapse. |
Use Scenario: Converting 12V adapter input to regulated 3.3V for DSL PHY and microcontroller subsystems. IC Role / Device Role / Timing Role: Isolated power stage with enable control for selective subsystem power gating. Use Value: EN pin logic compatibility and <10µA shutdown current support low-power modem sleep modes compliant with ITU-T G.99x standards. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2307DN-LF-Z (Monolithic Power) | 3A rated, 23V max input, 500kHz switching, N-channel sync rectification, no internal OCSET pin. | Requires external current sense resistor; higher frequency allows smaller magnetics but increases EMI filtering burden. | Preferred when board space is constrained and higher switching frequency is acceptable. |
| TPS5430DDAR (Texas Instruments) | 3A, 36V max input, 500kHz, external PMOS driver, no integrated switch, requires bootstrap capacitor. | Greater input voltage range and design flexibility, but adds 4–5 external components versus AP1538's minimal BOM. | Chosen when input exceeds 18V or when programmable soft-start and UVLO thresholds are required. |
Compared with MP2307DN-LF-Z and TPS5430DDAR, the AP1538SG-13 offers lowest component count for ≤18V inputs, built-in current limit programming, and optimized thermal performance in SOP-8L - making it ideal for cost-sensitive, space-constrained consumer power supplies where 300kHz operation balances size and noise.
Availability
AP1538SG-13 is available at Aetrix Electronics and suitable for PC motherboard VRMs, LCD monitor power supplies, and ADSL modem subsystems requiring stable component supply, RoHS-compliant packaging, and long-term industrial availability.
Supply support for AP1538SG-13 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
Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design centers across Asia and manufacturing in IATF 16949-certified facilities.
The AP1538 belongs to Diodes' high-efficiency DC/DC converter product line, designed specifically for portable and embedded systems requiring compact, low-component-count power solutions with robust protection and automotive-grade reliability options.
FAQ
What is the minimum recommended ROCSET resistor value for 5V output at 12V input?
The datasheet specifies a 3.0kΩ ROCSET resistor for VOUT = 5V and VIN = 12V. This sets the over-current threshold to approximately 5.5A peak, providing sufficient margin above the 3A continuous rating while maintaining thermal safety under worst-case ambient conditions.
Can AP1538SG-13 operate with input voltage below 3.6V?
No - the under-voltage lockout circuit disables operation below 3.3V VCC, and the recommended minimum input is 3.6V. Operation below this risks unstable regulation, reduced output current capability, and potential failure to initiate soft-start due to insufficient gate drive voltage for the internal PMOS.
How does the dual-exposed-pad SOP-8L-DEP variant differ thermally from standard SOP-8L?
The SOP-8L-DEP variant has θJC = 26°C/W versus 24°C/W for SOP-8L, due to additional thermal path through the second exposed pad connected to the Output node. Layout must isolate both pads to avoid shorting; recommended copper area under each pad is ≥90×50 mil (output) and ≥90×60 mil (VSS).
Is AP1538SG-13 qualified for automotive applications?
The AP1538SG-13 itself is not AEC-Q100 qualified; however, Diodes offers automotive-grade variants (e.g., AP1538Q) with PPAP documentation, IATF 16949 manufacturing, and extended temperature screening. Customers requiring automotive qualification must specify the "Q" suffix and contact Diodes sales directly.
AP1538SG-13 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.6V
- Voltage - Input (Max):
- 18V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 18V
- Current - Output:
- 3A
- Frequency - Switching:
- 300kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -20°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOP
AP1538SG-13 FAQ
1.How can I place an order for AP1538SG-13 through Aetrix?
Please submit a Request for Quotation (RFQ) for AP1538SG-13 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 AP1538SG-13 reliable?
The price and inventory of AP1538SG-13 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AP1538SG-13 is usually 5 days.
3.What payment methods are accepted for AP1538SG-13?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AP1538SG-13 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AP1538SG-13?
AP1538SG-13 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AP1538SG-13 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 AP1538SG-13?
For technical support, including AP1538SG-13 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AP1538SG-13 requirements.
6.How does Aetrix verify that AP1538SG-13 is sourced from the original manufacturer or authorized distributors?
All AP1538SG-13 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 AP1538SG-13 meets industry standards.
7.What is the process for return or replacement of AP1538SG-13?
All AP1538SG-13 units undergo pre-shipment inspection (PSI). If there is an issue with AP1538SG-13, 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 AP1538SG-13 part is unused and in its original packaging.
Return procedure for AP1538SG-13:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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