CSD18503Q5A - 40V N-Channel NexFET MOSFET 4.3mOhm | TI
MPN: CSD18503Q5A β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.42 | $1.42 |
| 10 | $1.28 | $12.80 |
| 100 | $1.08 | $108.00 |
| 500 | $0.95 | $475.00 |
| 1,000 | $0.85 | $850.00 |
Drop-in alternatives for CSD18503Q5A β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
CSD18563Q5A
β Drop-Inπ Reference alternative (not in catalog)
CSD18502Q5B
β Drop-Inπ Reference alternative (not in catalog)
CSD18540Q5B
β Drop-Inπ Reference alternative (not in catalog)
BSC0906NS
β‘ Same Packageπ Reference alternative (not in catalog)
CSD18503Q5A Maximum Ratings & Electrical Characteristics
| Polarity | N-Channel |
| Drain-Source Voltage VDS | 40 V |
| On-Resistance RDS(on) | 4.3 mOhm |
| Continuous Drain Current | 19 A (Ta), 100 A (Tc) |
| Power Dissipation | 3.1 W (Ta), 120 W (Tc) |
| Technology | NexFET |
| Package | 8-VSONP (DQJ), 5 mm x 6 mm |
| Mounting Type | Surface Mount |
| Operating Temperature | -55C to +150C |
| Configuration | Single FET |
| Gate-Source Voltage | [DATA_NEEDED: VGS rating] |
| Gate Charge Qg | [DATA_NEEDED: typical Qg] |
| Input Capacitance Ciss | [DATA_NEEDED: Ciss] |
| RDS(on) at 10V VGS (typ) | 3.4 mOhm |
| RoHS Status | Compliant |
| MSL Level | [DATA_NEEDED: MSL] |
CSD18503Q5A Pin Configuration
| Pin 1 | G β Gate |
| Pin 2 | S β Source |
| Pin 3 | S β Source |
| Pin 4 | S β Source |
| Pin 5 | S β Source |
| Pin 6 | S β Source |
| Pin 7 | S β Source |
| Pin 8 | S β Source |
| Pin PAD | D β Drain - exposed die pad on package underside |
Safe Operating Area (approximate, verify with TI datasheet)
Typical Applications
CSD18503Q5A is suitable for 6 applications: DC-DC Converter Power Stage, Motor Drive Half-Bridge, Hot-Swap and Load Switch, Battery Protection and BMS, Server and Telecom Power Distribution, Class-D Audio Amplifier Supply Stage.
DC-DC Converter Power Stage
The CSD18503Q5A serves as the low-side synchronous FET in 12-24 V input buck converters. Its 4.3 mOhm RDS(on) at 10 V gate drive keeps conduction loss low: at 20 A RMS, loss is only ~1.7 W, while the NexFET process keeps gate charge modest so switching loss stays acceptable at several hundred kHz. Placed on the converter power stage with the exposed drain pad soldered to a ground/power pour, the 120 W Tc rating provides headroom for peak loads. Designers should verify the SOA curve in the TI datasheet for pulsed current events such as startup and output shorts.
Recommended
Motor Drive Half-Bridge
In brushed-DC and BLDC motor drives on 12 V or 24 V buses, the CSD18503Q5A provides the low-side switch of half-bridge legs. The 40 V rating includes margin for inductive flyback above the rail, and 4.3 mOhm on-resistance limits heating during PWM operation and stall currents reaching tens of amps. The 5x6 mm SON package with drain pad enables compact multi-FET layouts on one heatsink pour. Pair with a gate driver providing fast turn-off and a bootstrap supply; use the TI datasheet thermal impedances to size copper area for the stall-current duty cycle.
Recommended
Hot-Swap and Load Switch
The 100 A (Tc) current capability and robust 40 V rating make the CSD18503Q5A well suited as the pass FET in hot-swap controllers and high-side or low-side load switches on 12 V and 24 V rails. During insertion events, the controller limits gate slew so the FET operates inside its SOA; the TI datasheet SOA curves should be checked against the controller time-out settings. Once fully enhanced, 4.3 mOhm on-resistance drops only ~0.17 V at 40 A, minimizing wasted power. The DQJ package exposed pad bonds to the board pour for the thermal path.
Recommended
Battery Protection and BMS
In 12 V lead-acid and low-voltage lithium battery systems, the CSD18503Q5A works as the discharge/charge path FET in battery management front ends. Its 40 V rating withstands transients during load-dump-like events on automotive-adjacent systems, and the low on-resistance keeps series loss below 2 W at 20 A continuous, preserving runtime. The -55C to +150C junction range supports harsh environments. In BMS designs the FET switches infrequently, so conduction loss dominates; designers size parallel FETs on the shared pour to meet current derating targets.
Recommended
Server and Telecom Power Distribution
Distributed power architectures in servers and telecom rectifiers use 12 V or 24 V intermediate buses where the CSD18503Q5A functions as an ORing or eFuse FET. The very low 4.3 mOhm RDS(on) minimizes distribution loss across high-availability rails, and the 120 W case-limited dissipation rating tolerates brief fault conditions during current-limit events. The surface-mount 5x6 mm SON footprint suits automated assembly on dense power boards. Verify avalanche energy ratings in the TI datasheet when inductive line impedance is present upstream.
Recommended
Class-D Audio Amplifier Supply Stage
The CSD18503Q5A can serve as the switching FET in half-bridge Class-D output stages and in the boost/buck front-end powering audio amplifiers from 12 V vehicle or 24 V PA systems. Low RDS(on) reduces distortion-contributing voltage drops across the switch, while the NexFET gate-charge profile supports the several-hundred-kHz PWM frequencies typical of Class-D modulators. The 40 V rating handles speaker inductive kick above the rail with snubbing. Use fast gate drivers and tight gate loops to limit ringing per TI gate-drive application guidance.
Recommended
Recommended Products Summary
Engineering reference data for CSD18503Q5A β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | CSD18563Q5A | CSD18502Q5B | BSC0906NS |
|---|---|---|---|---|
| Package | 8-VSONP (DQJ) 5x6 mm | 8-VSONP (DQJ) 5x6 mm - same | 8-VSONP (DQJ) 5x6 mm - same | PQFN 5x6 - same outline, verify pin map |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Infineon |
| VDS Rating | 40 V | 60 V | 40 V | 30 V |
| RDS(on) | 4.3 mOhm | [DATA_NEEDED] | [DATA_NEEDED] | [DATA_NEEDED] |
| Continuous Current | 19 A (Ta) / 100 A (Tc) | [DATA_NEEDED] | [DATA_NEEDED] | [DATA_NEEDED] |
| Power Dissipation | 3.1 W (Ta) / 120 W (Tc) | [DATA_NEEDED] | [DATA_NEEDED] | [DATA_NEEDED] |
| Technology | NexFET | NexFET | NexFET | OptiMOS |
| Operating Temperature | -55C to +150C | -55C to +150C | -55C to +150C | -55C to +150C |
Key Differentiators
- Lower VDS family with lowest RDS(on) at 40 V class (vs CSD18563Q5A)
- Same-footprint 40 V alternative with different loss balance (vs CSD18502Q5B)
- Voltage headroom vs 30 V cross-brand parts (vs BSC0906NS)
Design Notes
The 120 W Tc rating assumes the exposed drain pad is soldered to a substantial thermal pour. At ambient-cooled conditions the practical limit is 3.1 W, set by theta_JA of the DQJ package. Size copper pour per the TI datasheet thermal applications section; for example, at 20 A continuous the conduction loss is ~1.7 W, leaving little headroom at 25C ambient without extra copper.
Minimize the gate loop length between gate driver and pin 1 to reduce parasitic inductance and ringing. Place source connections (pins 2-3) directly over the driver return path. The exposed drain pad must connect to a stitched multi-layer pour with thermal vias; a single-layer connection significantly degrades the theta_JA from datasheet values.
Do not exceed the 40 V VDS rating including switching spikes and inductive flyback - add snubbing or clamp circuits on motor and transformer loads. Also, the 4.3 mOhm spec applies at the datasheet test gate voltage; driving with less gate voltage increases RDS(on) sharply. Verify SOA for pulsed loads such as hot-swap events rather than assuming the 100 A DC-case figure applies.
Compliance Information
RoHS compliance per TI product page and distributor listings. Detailed REACH/halogen declarations available via TI quality documents; not present in retrieved data.
