BSP135H6906XTSA1 - 600V N-Ch Depletion MOSFET | Infineon
MPN: BSP135H6906XTSA1 β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.62 | $16.20 |
| 100 | $1.38 | $138.00 |
| 500 | $1.15 | $575.00 |
| 1,000 | $0.95 | $950.00 |
| 3,000 | $0.78 | $2,340.00 |
BSP135H6906XTSA1 Overview
A depletion-mode MOSFET is a field-effect transistor that conducts at zero gate-source voltage because the channel is physically doped to be conductive by default. Applying a negative VGS (for an N-channel device) depletes carriers and pinches the channel off. This is the opposite polarity of the enhancement-mode MOSFETs (NMOS/PMOS) that dominate digital logic, where VGS must exceed a threshold to turn the device on. Depletion parts therefore need no driver, no charge pump, and no bootstrap, and they remain on during power supply startup before any controller IC is alive - which is precisely why they are used as bypass, startup, and reference elements.
Key features include a maximum drain-source voltage (VDS) of 600 V, a continuous drain current (ID) of 120 mA at TA=25 C, a maximum on-resistance (RDS(on)) of 45 Ohm at VGS=0 V, and a 1.8 W power rating in the compact SOT-223 (PG-SOT223-4) package with a tab that acts as the drain. The depletion-mode behavior gives it a normally-on characteristic so it can be used as a constant-current source when combined with a source resistor, or as an automatic bypass switch that turns off only when gate bias is applied.
The device is built on Infineon's planar SIPMOS process, which is optimized for high-voltage switching and analog depletion operation. Its RDS(on) versus VGS curve is monotonic, allowing analog regulation rather than the binary on/off behavior of standard enhancement MOSFETs. This makes the BSP135 well suited to circuits where predictable analog current is needed without closed-loop control.
Typical applications include offline startup bypass in switched-mode power supplies, over-voltage protection clamps, in-rush current limiters, active dummy loads, and offline voltage references. Automotive-grade variants exist with AEC-Q101 qualification, supporting 12 V and 24 V body electronics as well as industrial auxiliary supplies.
When designing with the BSP135, remember that it is normally-on: the circuit must tolerate continuous conduction when the system is unpowered, and the gate must be actively pulled below VGS(off) (about -1.5 V to -3.5 V for this part) to switch it off. A simple Zener-resistor network can derive the negative gate bias from the drain.
This page synthesizes distributor pricing, SOT-223 drop-in alternatives, and practical depletion-mode design notes that the manufacturer datasheet alone does not provide.
Drop-in alternatives for BSP135H6906XTSA1 β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with BSP135H6906XTSA1 (same form factor and footprint) β differing in Package, Technology, MSL Level, Operating Temperature Range, FET Type.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
BSP135H6327XTSA1
β Drop-Inβ In Stock
$0.43 / Unit
View Datasheet βBSP135L6327HTSA1
β Drop-Inπ Reference alternative (not in catalog)
BSP125H6327XTSA1
β Drop-Inβ In Stock
$0.38 / Unit
View Datasheet βBSP316PH6327XTSA1
β Drop-Inβ In Stock
$0.21 / Unit
View Datasheet βBSP315PH6327XTSA1
β Drop-Inβ In Stock
$0.31 / Unit
View Datasheet βBSD214SNH6327XTSA1
β Drop-Inβ In Stock
$0.27 / Unit
View Datasheet βBSP135H6906XTSA1 Maximum Ratings & Electrical Characteristics
| FET Type | N-Channel Depletion Mode |
| Drain-Source Voltage (VDS) Max | 600 V |
| Continuous Drain Current (ID) at TA=25C | 120 mA |
| RDS(on) Max at VGS=0V | 45 Ohm |
| Power Dissipation (PD) Max | 1.8 W |
| Gate Threshold Voltage (VGS(off)) | Depletion mode (normally-on) |
| Operating Temperature Range | -55C to +150C |
| Package | PG-SOT223-4 (SOT-223, 3+tab) |
| Mounting Type | Surface Mount |
| Pin Count | 4 (3 leads + drain tab) |
| Technology | SIPMOS (planar high-voltage) |
| MSL Level | 1 (unlimited) |
| RoHS Status | Compliant |
| Automotive Qualification | AEC-Q101 (per datasheets.com parametric record) |
| Lead-Free | Yes |
BSP135H6906XTSA1 Pin Configuration
| Pin 1 | Gate β Gate terminal; pull to VGS(off) (~-2 V) to switch off the depletion channel |
| Pin 2 | Drain β Drain terminal; also bonded to the metal tab on the rear of the package for thermal dissipation |
| Pin 3 | Source β Source terminal |
| Pin 4 | Source (Tab) β Source-connected tab on rear of package; solder to source copper pour for thermal relief |
Safe Operating Area - DC Continuous
Typical Applications
BSP135H6906XTSA1 is suitable for 6 applications: Offline SMPS Startup Bypass, Over-Voltage Protection Clamp, In-Rush Current Limiter, Offline Voltage Reference / Constant-Current Source, Automotive 12V/24V Auxiliary Supply, Active Dummy Load / Bleeder Circuit.
Offline SMPS Startup Bypass
The BSP135H6906XTSA1 fits offline SMPS startup bypass because it is normally-on at VGS=0 V and rated 600 V VDS. It carries the auxiliary winding bias current (typically 5-20 mA) from the rectified 310 VDC bulk rail to the controller VCC pin during cold-start, then is switched off by the controller once the auxiliary winding takes over. Using the BSP135 instead of a conventional startup resistor eliminates the continuous 0.5-2 W dissipation loss that plagues high-voltage supplies, often improving standby efficiency by 1-3 percent. The depletion characteristic means the circuit sees the auxiliary winding voltage from the moment AC is applied, no MCU initialization delay.
Recommended
Over-Voltage Protection Clamp
Used as an active over-voltage clamp, the BSP135H6906XTSA1 conducts the moment the rail exceeds its threshold, shunting fault current away from downstream components. Its 600 V rating comfortably covers 110/220 VAC rectified rails (peak 310 V) plus inductive transients, and its normally-on state means there is no firmware delay before protection engages. The gate can be pulled to a regulated negative rail (typically -5 V) by a Zener-resistor network to set the precise clamp voltage. This topology is common in industrial 24 V systems and offline appliance protection where response time is microseconds, not milliseconds.
Recommended
In-Rush Current Limiter
The BSP135H6906XTSA1 acts as an in-rush current limiter when placed in series with a bulk capacitor and a source resistor. At power-on, the depletion device is on and conducts the initial charging current; once VGS is pulled negative by a sensed voltage across the source resistor, the channel pinches off and limits the steady-state current. The 45 Ohm RDS(on) gives predictable current limiting around 30-50 mA without external feedback, and the 600 V rating supports universal AC input. This passive analog limiter is favored over PWM active limiters for its simplicity and zero quiescent draw in steady state.
Recommended
Offline Voltage Reference / Constant-Current Source
With a single source resistor, the BSP135H6906XTSA1 forms a simple two-terminal constant-current source suitable for offline biasing of optocouplers, Zener reference diodes, or low-power analog circuits. The 45 Ohm RDS(on) at VGS=0 V combined with a few kOhm of source resistance gives a regulated current of roughly 5-15 mA independent of drain voltage (above pinch-off). This is widely used as a passive current reference in isolated gate-drive bias supplies and as a stable pull-up element in 600 V analog front-ends.
Recommended
Automotive 12V/24V Auxiliary Supply
AEC-Q101-qualified depletion-mode variants of the BSP135 are used in automotive 12 V and 24 V body-electronics auxiliary supplies where normally-on behavior simplifies cold-start sequencing and redundant power paths. The part handles load-dump transients up to its 600 V rating, far above the 24 V system steady-state level, providing robust margin for inductive kickback and jump-start events. The SOT-223 (PG-SOT223-4) footprint is compatible with automotive PCB assembly standards and supports automated optical inspection.
Recommended
Active Dummy Load / Bleeder Circuit
In high-voltage test equipment and bleeder circuits, the BSP135H6906XTSA1 is used as an adjustable active load. By varying VGS between 0 V and the VGS(off) point, the designer can sweep drain current from full conduction (about 120 mA) down to microampere leakage. The 1.8 W SOT-223 package dissipates up to its rated power with adequate copper, and the depletion behavior means the load is engaged even when the test controller is unpowered - a useful safety feature for capacitor discharge applications.
Recommended
Recommended Products Summary
Engineering reference data for BSP135H6906XTSA1 β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | BSP135H6327XTSA1 | BSP135L6327HTSA1 | BSP125H6327XTSA1 | BSP316PH6327XTSA1 | BSP315PH6327XTSA1 | BSD214SNH6327XTSA1 |
|---|---|---|---|---|---|---|---|
| Package | PG-SOT223-4 (SOT-223, 3+tab) | PG-SOT223-4 - same | PG-SOT223-4 - same | PG-SOT223-4 - same | PG-SOT223-4 - same | PG-SOT223-4 - same | PG-SOT223-4 - same |
| Brand | Infineon Technologies | Infineon Technologies | Infineon Technologies | Infineon Technologies | Infineon Technologies | Infineon Technologies | Infineon Technologies |
| FET Type / Polarity | N-Channel Depletion (normally-on) | N-Channel Depletion | N-Channel Depletion | N-Channel Depletion | P-Channel Enhancement | P-Channel Enhancement | N-Channel Enhancement |
| VDS Max | 600 V | 600 V | 600 V | 250 V | -60 V | -60 V | 250 V |
| Continuous Drain Current | 120 mA | 120 mA | 120 mA | 200 mA | -1.9 A | -1.9 A | 0.6 A |
| RDS(on) Max | 45 Ohm | 45 Ohm | 45 Ohm | 20 Ohm | 0.25 Ohm | 0.25 Ohm | 5 Ohm |
| Power Dissipation (PD) Max | 1.8 W | 1.8 W | 1.8 W | 1.8 W | 1.8 W | 1.8 W | 1.8 W |
| Operating Mode | Depletion (normally-on) | Depletion | Depletion | Depletion | Enhancement | Enhancement | Enhancement |
Key Differentiators
- Only Infineon N-channel depletion-mode MOSFET in PG-SOT223-4 at 600 V (vs BSP316PH6327XTSA1)
- Higher blocking voltage than lower-VDS depletion alternatives (vs BSP125H6327XTSA1)
- AEC-Q101 automotive-qualified option exists in same die (vs BSD214SNH6327XTSA1)
Design Notes
The BSP135H6906XTSA1 is normally-on at VGS=0 V. Engineers familiar with enhancement-mode MOSFETs may incorrectly assume the device is off when un-driven; in reality it conducts the moment the drain voltage exceeds 0 V. The circuit must tolerate this continuous conduction at power-up, and an explicit negative gate bias (typically derived from a Zener-resistor network on the drain) must be applied to switch the device off. Forgetting this is the most common design mistake and can result in permanently-on output rails.
At 100 mA drain current and 45 Ohm RDS(on), the part dissipates about 0.45 W in the SOT-223 (PG-SOT223-4) package, well within its 1.8 W rating. At full 120 mA with the drain tab soldered to a 1 square-inch copper pour, theta_JA drops to roughly 70 C/W, supporting full-rated current up to TA=125 C ambient. Without copper area, theta_JA rises to 150 C/W and continuous current should be limited to about 50 mA. The drain tab is pin 2 electrically and must be soldered for thermal relief.
Place the BSP135H6906XTSA1 with the drain tab connected to a copper pour of at least 1 square inch (about 645 square mm) on the top layer for thermal spreading. The SOT-223 footprint is non-standard (it is wider than SO-8), so verify the land pattern matches Infineon's PG-SOT223-4 reference. Keep the high-voltage drain trace away from low-voltage gate and source traces by at least 3 mm to prevent surface arcing at 600 V, and consider slotting the PCB between drain and gate to increase creepage.
For the offline SMPS startup bypass topology, route the gate bias Zener-resistor network close to the gate pin to minimize parasitic inductance. A 100 kOhm gate resistor plus a 5.6 V Zener to ground (referenced to source) provides a clean negative gate bias that turns the device off once the auxiliary winding takes over. The gate-source capacitance (Ciss typically 50-100 pF) is small enough that no extra gate drive buffer is required.
Compliance Information
RoHS and REACH compliant per Infineon product page. AEC-Q101 qualification noted by datasheets.com parametric record (variant dependent). Halogen-free status not explicitly stated in provided data.
