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Diodes Incorporated ZTX557STZ
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- Part No.:
- ZTX557STZ
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Bipolar Transistors
- Package:
- E-Line-3, Formed Leads
- Datasheet:
-
ZTX557STZ.pdf
- Description:
- TRANS PNP 300V 0.5A E-LINE
- Quantity:
- Payment:
- Shipping:
Inventory:3,141
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Product details
Overview
ZTX557STZ from Diodes Incorporated is a PNP silicon planar medium-power high-voltage transistor rated for −300 V VCEO, −300 V VCBO, and −0.5 A continuous collector current, with 1.0 W power dissipation. It operates across −55°C to +200°C and is used in high-voltage switching and linear regulation circuits in industrial power supplies and relay drivers.
For engineers reviewing the ZTX557STZ datasheet, ZTX557STZ pinout, ZTX557STZ application, or ZTX557STZ equivalent, key selection criteria include verified −300 V breakdown ratings, hFE = 50–300 at −10 mA, fT = 75 MHz, VCE(sat) = −0.3 V at −50 mA/−5 mA, and TO-92 compatible packaging for through-hole board integration.
Technical Context
This PNP bipolar junction transistor employs a planar epitaxial structure optimized for high-voltage blocking and medium-power switching. Its −300 V VCEO and VCBO ratings enable use in flyback snubbers and HV DC-DC stage isolation where voltage transients exceed 250 V.
The device delivers hFE ≥ 50 at −10 mA and ≥ 50 at −50 mA (VCE = −10 V), with fT = 75 MHz ensuring adequate gain-bandwidth for fast-switching control loops up to ~10 MHz under typical bias conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | −300 V - supports operation in 240 V AC-derived rails with ≥2× safety margin against surge transients |
| IC (continuous) | −0.5 A - suitable for driving relays, solenoids, or small motors without heatsinking below 0.3 W dissipation |
| Ptot | 1.0 W - enables direct mounting on PCBs with minimal copper area for thermal relief in space-constrained designs |
| hFE | 50–300 - provides stable current amplification across −10 mA to −50 mA loads, supporting predictable base drive sizing |
| fT | 75 MHz - allows use in high-speed switching applications such as PWM-controlled HV gate drivers up to 5–10 MHz |
| VCE(sat) | −0.3 V @ −50 mA/−5 mA - minimizes conduction loss and self-heating during saturated switching in low-duty-cycle loads |
Pinout & Package
Package: TO-92 compatible (3-lead plastic package, E-line configuration). Pin identification follows standard E-line orientation: viewed from bottom with leads down and flat side facing viewer, left-to-right pins are Emitter (E), Base (B), Collector (C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| E (Emitter) | Current source terminal for PNP operation | Connected to higher potential rail; defines reference for base bias and collector load placement |
| B (Base) | Control input for minority-carrier injection | Receives negative current to turn on; requires series resistor to limit IB per hFE and VBE(sat) = −1 V |
| C (Collector) | Current sink terminal, connected to load | Typically tied to ground or low-side return; must withstand −300 V reverse bias when off |
Key Features
| Feature | Design Value |
|---|---|
| High-voltage blocking | −300 V VCEO/VCBO enables direct interface with 230 V AC rectified buses without external clamping |
| Medium-power capability | 1.0 W Ptot supports sustained −0.5 A switching without forced air or heatsink in ambient ≤50°C |
| Wide temperature range | −55°C to +200°C Tj rating permits deployment in automotive engine compartments and industrial motor controls |
| Stable DC current gain | hFE ≥ 50 at both −10 mA and −50 mA ensures consistent base drive design across load current variations |
Applications
| Industrial Relay Drivers | High-Voltage Flyback Snubbers |
|---|---|
Use Scenario: Driving 24 V or 48 V coil relays in PLC output modules with 230 V AC line isolation. IC Role / Device Role / Timing Role: PNP switch controlling relay coil current path to ground; operates in saturation with fixed base drive. Use Value: −300 V VCEO prevents breakdown during inductive kickback spikes exceeding −200 V, eliminating need for external TVS. | Use Scenario: Clamping voltage spikes across transformer primary windings in offline flyback converters. IC Role / Device Role / Timing Role: Active clamp transistor absorbing energy during MOSFET turn-off; biased in linear region for controlled dissipation. Use Value: 1.0 W Ptot and −300 V rating allow reliable clamping of 200–280 V transients without derating at +85°C ambient. |
| Linear HV Regulators | Discrete BJT Amplifier Stages |
Use Scenario: Pass element in adjustable negative-output linear regulators powering analog sensor front-ends from −200 V rails. IC Role / Device Role / Timing Role: Series pass transistor operating in active mode; dissipates regulated power as heat. Use Value: hFE stability over −10 mA to −50 mA enables precise current mirror-based error amplifier feedback without gain drift. | Use Scenario: Input stage in wideband differential amplifiers requiring high common-mode rejection above 100 V. IC Role / Device Role / Timing Role: PNP emitter follower providing high-input impedance and low-output impedance buffering. Use Value: fT = 75 MHz ensures >10 MHz bandwidth at unity gain, supporting fast transient response in precision timing circuits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PNP high-voltage switching applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MJD2955G | TO-220 package, −70 V VCEO, −10 A IC, 75 W Ptot | Designed for high-current, low-voltage power stages; unsuitable for >−100 V blocking | Select only if replacing ZTX557STZ in low-voltage, high-current roles with heatsink provision |
| BCW68G | SOT-23 package, −60 V VCEO, −0.8 A IC, 0.5 W Ptot | Surface-mount, lower voltage rating, reduced thermal mass | Use only in compact, low-voltage (<−48 V), low-duty-cycle signal switching where TO-92 footprint is unavailable |
Compared with MJD2955G and BCW68G, ZTX557STZ uniquely balances −300 V blocking, TO-92 mountability, and 1 W dissipation-making it irreplaceable in space-limited, high-voltage discrete switching where neither high-current nor SMT form factors apply.
Availability
ZTX557STZ is available at Aetrix Electronics and suitable for industrial relay drivers, high-voltage flyback snubbers, linear HV regulators, and discrete BJT amplifier stages requiring stable component supply and long-term manufacturability.
Supply support for ZTX557STZ 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 China, Taiwan, and the US.
ZTX557STZ belongs to the ZTX series of high-voltage bipolar transistors designed specifically for industrial power control, relay interfacing, and analog signal conditioning in harsh-temperature environments.
FAQ
What is the maximum safe operating voltage for ZTX557STZ in continuous DC applications?
The ZTX557STZ is rated for −300 V collector-emitter voltage (VCEO) and −300 V collector-base voltage (VCBO) at Tj = 25°C. Derating is required above 25°C: VCEO decreases by approximately 0.25 V/°C above 25°C. At +125°C junction temperature, the safe continuous DC voltage drops to ~−275 V.
Can ZTX557STZ be used in avalanche mode?
No. The ZTX557STZ is not characterized or rated for controlled avalanche operation. Its absolute maximum ratings define hard limits-not operational modes. Intentional avalanche use risks irreversible degradation due to localized thermal runaway, especially given its 1.0 W power limit and TO-92 thermal resistance.
Is ZTX557STZ RoHS compliant and lead-free?
Yes. ZTX557STZ is RoHS compliant and lead-free per Diodes Incorporated's product change notice PN-2017-01. The device uses matte tin-plated leads and meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1), with unlimited floor life at ≤30°C/60% RH.
How does ZTX557STZ compare to ZTX556 in practical circuit design?
ZTX556 shares identical package, pinout, and thermal specs but has −200 V VCEO/VCBO and slightly higher hFE min (100 vs. 50 at −10 mA). Use ZTX557STZ only where −300 V blocking is mandatory; otherwise, ZTX556 offers better gain consistency at light loads and lower cost in non-HV applications.
ZTX557STZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- E-Line-3, Formed Leads
- Packaging:
- Tape & Box (TB)
- Product Status:
- Obsolete
- Transistor Type:
- PNP
- Current - Collector (Ic) (Max):
- 500 mA
- Voltage - Collector Emitter Breakdown (Max):
- 300 V
- Vce Saturation (Max) @ Ib, Ic:
- 300mV @ 5mA, 50mA
- Current - Collector Cutoff (Max):
- 100nA (ICBO)
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 50 @ 50mA, 10V
- Power - Max:
- 1 W
- Frequency - Transition:
- 75MHz
- Operating Temperature:
- -55°C ~ 200°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- E-Line (TO-92 compatible)
ZTX557STZ FAQ
1.How can I place an order for ZTX557STZ through Aetrix?
Please submit a Request for Quotation (RFQ) for ZTX557STZ 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 ZTX557STZ reliable?
The price and inventory of ZTX557STZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZTX557STZ is usually 5 days.
3.What payment methods are accepted for ZTX557STZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZTX557STZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ZTX557STZ?
ZTX557STZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ZTX557STZ 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 ZTX557STZ?
For technical support, including ZTX557STZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZTX557STZ requirements.
6.How does Aetrix verify that ZTX557STZ is sourced from the original manufacturer or authorized distributors?
All ZTX557STZ 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 ZTX557STZ meets industry standards.
7.What is the process for return or replacement of ZTX557STZ?
All ZTX557STZ units undergo pre-shipment inspection (PSI). If there is an issue with ZTX557STZ, 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 ZTX557STZ part is unused and in its original packaging.
Return procedure for ZTX557STZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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