Yesterday I wrote a bit about the DC power jack power supply circuit of the Dell Inspiron laptop which I want to repair. Today I want to write another note on the power supply schematic diagram because I haven't completely looked at the components it uses. I want to know what exact parts are used and what their function and electrical parameters are.
Below is the circuit diagram of the power supply circuit.
The physical motherboard PCB showing this power supply circuit part above is shown below.
From my observation on the schematic the major components used are as follows:
1. Transistors
The following 5 transistors were used in the above power supply circuit.
a. 2N7002K-2-GP(PQ3809,PQ3810)
The 2N7002K-2-GP is a small signal N-channel enhancement-mode MOSFET commonly used in low-power switching and signal control applications. Packaged in a compact SOT-23 form, it features a low gate threshold voltage, making it ideal for interfacing with logic-level control signals. In the Dell Inspiron 14z5423 schematic (e.g., PQ3810 on page 38), it likely serves as a control switch in the adapter detection or protection circuit, helping manage the 19V power input from the DC jack. Its robustness, fast switching speed, and ease of use make it a popular choice for power path control in laptops and portable electronics.
b. FDV301N-NL-GP(PQ3801)
The FDV301N-NL-GP is a digital FET, a small-signal N-channel MOSFET designed for low-voltage, high-speed switching applications. Housed in an ultra-compact SOT-23 or SOT-323 package, it is ideal for space-constrained circuits. With a low gate threshold voltage and fast switching characteristics, it is commonly used in load switching, logic level shifting, and power management circuits. The "NL" suffix typically indicates a lead-free, RoHS-compliant version. In notebook schematics like the Dell Inspiron 14z5423, the FDV301N-NL-GP may be used for controlling power rails or enabling/disabling sub-circuits through logic-level signals, offering efficient and reliable performance in compact electronics.
The PMBS3904-1-GP is a general-purpose NPN bipolar junction transistor (BJT), commonly used for switching and amplification in low-power electronic circuits. It is the surface-mount version of the widely known 2N3904 and is typically packaged in a compact SOT-23 form factor, making it suitable for densely packed PCBs. With moderate current handling, fast switching speed, and good gain characteristics, it is ideal for signal amplification, digital logic interfacing, and small-load switching tasks. In devices like laptops or embedded systems, the PMBS3904-1-GP is often found in control circuits, sensor interfaces, and power enable logic, where reliable and efficient performance is required in a small footprint.
The PDTC124EU is a compact, surface-mount NPN resistor-equipped transistor (RET) designed to simplify circuit design by integrating biasing resistors within the transistor package. Manufactured by Nexperia, this device is housed in a SOT-323 (SC-70) package, making it ideal for space-constrained applications.
The PDTA124EU-1-GP is a PNP resistor-equipped transistor (RET) designed for general-purpose switching applications, featuring integrated bias resistors that simplify circuit design by eliminating the need for external base resistors. Packaged in a compact SOT-323 (SC-70) form, this device includes a 22 kΩ base resistor and a 22 kΩ base-emitter resistor, allowing for efficient and space-saving layouts. With a collector-emitter voltage rating of –50 V and a collector current capability of –100 mA, it is well-suited for use in digital switching, low-power control circuits, and signal conditioning tasks in compact electronic devices such as laptops and embedded systems.
f. S17121DN-T1-Q-GP(PU3801)
The S17121DN-T1-Q-GP is a P-channel TrenchFET® power MOSFET developed by Vishay Siliconix. This device is designed for efficient switching applications, particularly in power management systems such as notebook battery charging and adapter switching.
2. Diodes
The following diodes were used.
a. P6SBMJ24APT-GP(PD3801)
b. SM24DTCT-GP-U(PD3804)
c. BAV99-5-GP-U(PD3803)
These diodes are explained briefly below.
a. P6SBMJ24APT-GP
The P6SBMJ24APT-GP is a transient voltage suppressor (TVS) diode designed to protect electronic circuits from voltage spikes and surges. Manufactured by Chenmko Enterprise Co. Ltd., this component features a glass-passivated junction for enhanced reliability and stability. It is housed in a DO-214AA (SMB) surface-mount package, making it suitable for compact circuit designs.
b. SM24DTCT-GP-U
The SM24DTCT-GP-U is a transient voltage suppressor (TVS) diode, designed to protect sensitive electronic circuits from voltage spikes and surges. Manufactured by Chenmko Enterprise Co. Ltd., this component features a glass-passivated junction for enhanced reliability and stability. It is housed in a DO-214AA (SMB) surface-mount package, making it suitable for compact circuit designs.
In operation, the SM24DTCT-GP-U remains non-conductive during normal voltage conditions. However, when the voltage exceeds its breakdown threshold, the diode conducts and clamps the voltage to a safe level, thereby protecting sensitive components downstream. This makes it particularly useful in applications such as power supply lines, adapter inputs, and other areas where voltage transients are a concern.
c. BAV99-5-GP-U
The BAV99-5-GP-U is a dual high-speed switching diode housed in a compact SOT-23 surface-mount package. It consists of two diodes connected in series, making it suitable for applications requiring fast switching and signal routing. With a reverse voltage rating of up to 75 V and a forward current capacity of 150 mA per diode, it is ideal for tasks such as signal clamping, voltage steering, and general-purpose switching in digital and analog circuits. Its fast recovery time and low capacitance enhance performance in high-speed applications. The "GP" suffix indicates compliance with RoHS standards, ensuring the component is lead-free and environmentally friendly.
3. Capacitors
a. SCD1U225V3KX-GP(PC3801)
The SCD1U25V3KX-GP is a surface-mount aluminum electrolytic capacitor commonly found in laptop and notebook schematics, such as those from Dell and Lenovo. The part number suggests it is 1uF 25V electrolytic SMD capacitor.
b. SCD01U50V2KX-GP(PC3803,PC3804,PC3805)
The SCD01U50V2KX-GP is a surface-mount ceramic capacitor commonly used in electronic circuits for functions such as decoupling, filtering, and timing.
These 0.01uF, 50V capacitors are typically employed in power management sections of devices like laptops and embedded systems, where they help stabilize voltage levels and filter out noise. Their compact size and reliable performance make them suitable for high-density circuit boards.
c. SC10U25V5KX-GP(PC3806)
The SC10U25V5KX-GP is a surface-mount ceramic capacitor commonly found in laptop and notebook schematics, such as those from Dell and Lenovo.
These 10uF,25V capacitors are typically used for decoupling, filtering, or timing applications in power management and signal conditioning circuits.
4.Resistors
The following resistors were found in the above dell laptop power supply schematic:
a. 100KR2J-1-GP(PR3814,PR3815,PR3811)
- 100kohm smd resistors
b. 3K3R6J-GP(PR3816)
The 3K3R6J-GP is a resistor with a resistance value of 3.3 kΩ (3,300 ohms) and a tolerance of ±5%, as indicated by the "J" in its designation. The "GP" suffix typically denotes RoHS compliance, indicating that the component is lead-free and environmentally friendly. Resistors like the 3K3R6J-GP are widely used in electronic circuits for purposes such as voltage division, biasing active components, and current limiting. The 3.3 kΩ value is standard and often employed in analog signal paths, pull-up or pull-down configurations, and timing circuits.
c. 0R0603-PAD-2-GP
The 0R0603-PAD-2-GP is a zero-ohm resistor in a 0603 surface-mount package, commonly used in electronic circuit designs.
🔧 Key Characteristics:
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Resistance: 0 ohms (acts as a jumper)
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Package Size: 0603 (1.6 mm × 0.8 mm)
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Function: Serves as a configurable jumper or bridge between PCB traces
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Designation: "PAD-2" may indicate a specific pad layout or placement in the design
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Compliance: "GP" denotes RoHS compliance (lead-free, environmentally friendly)
🧰 Common Applications:
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Configuration Options: Allows designers to easily modify circuit configurations without altering the PCB layout
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Signal Routing: Facilitates signal routing during prototyping or testing phases
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Manufacturing Flexibility: Provides options for enabling or disabling certain features in different product versions
Zero-ohm resistors like the 0R0603-PAD-2-GP are essential components in modern electronics, offering flexibility and ease in circuit design and manufacturing processes.
d. 33R2J-2-GP(PR3808,PR3807)
The 33R2J-2-GP is a surface-mount resistor with a resistance value of 33.2 ohms and a tolerance of ±5%. The "J" denotes the 5% tolerance, while the "2" typically indicates the package size, likely corresponding to the 0805 (2012 metric) footprint. The "GP" suffix signifies that the component is RoHS-compliant, indicating it is lead-free and environmentally friendly.
Resistors like the 33R2J-2-GP are commonly used in electronic circuits for current limiting, voltage division, and signal conditioning. Their compact size makes them suitable for high-density printed circuit boards (PCBs) in applications such as laptops, embedded systems, and consumer electronics. While specific power ratings can vary, resistors in the 0805 package typically handle up to 0.125W under standard conditions.
e.15KR2J-1-GP(P3802)
The 15KR2J-1-GP is a surface-mount resistor with a resistance value of 15 kilohms (15 kΩ) and a tolerance of ±5%, as indicated by the "J" in its designation. The "R2" suggests a specific package size, likely corresponding to the 0402 (1005 metric) footprint. The "1" may denote a particular series or manufacturer-specific code, and "GP" signifies that the component is RoHS-compliant, indicating it is lead-free and environmentally friendly.
Resistors like the 15KR2J-1-GP are commonly used in electronic circuits for purposes such as voltage division, biasing active components, and current limiting. Their compact size makes them suitable for high-density printed circuit boards (PCBs) in applications like laptops, embedded systems, and consumer electronics. While specific power ratings can vary, resistors in the 0402 package typically handle up to 0.063 W under standard conditions.
f. 2K2R2J-2-GP(PR3806)
The 2K2R2J-2-GP is a surface-mount resistor with a resistance value of 2.2 kilohms (2.2 kΩ) and a tolerance of ±5%, as indicated by the "J" in its designation. The "R2" suggests a specific package size, likely corresponding to the 0402 (1005 metric) footprint. The "2" may denote a particular series or manufacturer-specific code, and "GP" signifies that the component is RoHS-compliant, indicating it is lead-free and environmentally friendly.
Resistors like the 2K2R2J-2-GP are commonly used in electronic circuits for purposes such as voltage division, biasing active components, and current limiting. Their compact size makes them suitable for high-density printed circuit boards (PCBs) in applications like laptops, embedded systems, and consumer electronics. While specific power ratings can vary, resistors in the 0402 package typically handle up to 0.063 W under standard conditions.
Thats it. These are all the components that are on the page 38 which is about the power supply circuit of dell inspiron. You can download the schematic diagram and the whole dell laptop schematic pdf file from the link below.
