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Texas Instruments 78ST235HC
- Part No.:
- 78ST235HC
- Manufacturer:
- Texas Instruments
- Package:
- 3-SIP Module
- Datasheet:
-
78ST235HC.pdf
- Description:
- IC REG BCK 3.45V 2A SIP MODULE-3
- Quantity:
- Payment:
- Shipping:
Inventory:3,026
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Product details
Overview
78ST235HC from Power Trends, Inc. is a 2 A, 3.45 V fixed-output integrated switching regulator with internal inductor, operating from 7–15 V input (for 3.3–3.5 V versions) and delivering >82% efficiency at 9 VIN/2 A/5 VOUT. It features short-circuit and over-temperature protection and is used in space-constrained industrial power supplies requiring stable low-noise DC-DC conversion.
For engineers reviewing the 78ST235HC datasheet, 78ST235HC pinout, 78ST235HC application, or 78ST235HC equivalent, key selection criteria include its self-contained inductor architecture, ±1.0% output voltage tolerance at full load, 1 MHz switching frequency, thermal derating behavior up to +85°C, and mandatory 100 µF electrolytic/tantalum output capacitor requirement.
Technical Context
The 78ST235HC implements a monolithic synchronous buck topology with laser-trimmed feedback for 3.45 V output accuracy. Its ceramic substrate enables high thermal conductivity and supports convection-cooled operation up to 2 A without external heatsinking under specified airflow (40–60 LFM).
It integrates control logic, power switch, freewheeling diode, and magnetic core in a single package. Protection functions are fully autonomous-no external components required for short-circuit or over-temperature shutdown, and recovery is automatic after fault removal.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 3.45 V ±1.0% (laser-trimmed; ensures stable reference without external resistor network) |
| Max Output Current | 2.0 A continuous (derates above +70°C ambient per published thermal chart) |
| Input Voltage Range | 7–15 V (valid for Vo ≤ 3.5 V; enables direct use with 9 V or 12 V rails) |
| Switching Frequency | 1.0 MHz ±5% (enables compact external filtering with <1 µF ceramic input cap) |
| Ripple/Noise | 1% VOUT (measured at 2 A load with 100 µF output cap; defines EMI filter sizing) |
| Efficiency | 82% min at 9 VIN, 2 A, 3.45 VOUT (determines thermal budget and board-level power loss) |
| Thermal Resistance θJA | 38 °C/W (free-air convection, 40–60 LFM; sets max power dissipation before derating) |
Pinout & Package
78ST235HC uses a 3-pin through-hole package (Package Style 500, horizontal mount), with pins arranged linearly and spaced 0.1" apart. The package is epoxy-molded with ceramic substrate for enhanced thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | VIN | Unregulated positive input (7–15 V); requires local 1 µF ceramic decoupling) |
| 2 | GND | Power and signal ground reference; must be low-impedance connection to minimize noise coupling) |
| 3 | VOUT | Regulated 3.45 V output; requires mandatory 100 µF electrolytic/tantalum bulk capacitance) |
Key Features
| Feature | Design Value |
|---|---|
| Self-contained inductor | Eliminates external magnetics and layout sensitivity; reduces BOM count and PCB area by ~35% vs discrete buck designs |
| ±1.0% output tolerance | Laser trimming ensures tight regulation across line/load/temperature-no post-assembly calibration needed |
| Fast transient response | 100 µs recovery time with ≤5% overshoot/undershoot on 50% load step-supports dynamic digital loads |
| Integrated protection | Autonomous short-circuit and over-temperature shutdown with auto-recovery-no external sense or latch circuitry required |
| 1 MHz switching | Enables use of small, low-ESR ceramic capacitors for input/output filtering-reduces size and cost vs lower-frequency ISRs |
Applications
| Industrial Sensor Node | Programmable Logic Controller I/O Module |
|---|---|
Use Scenario: Compact remote sensor node powered from 12 V field bus with microcontroller, ADC, and RS-485 transceiver. IC Role / Device Role / Timing Role: Primary 3.45 V supply for mixed-signal SoC and analog front-end. Use Value: Self-contained inductor and 1 MHz operation allow full power stage in <0.3 in² footprint; ±1% tolerance ensures ADC reference stability. | Use Scenario: DIN-rail mounted PLC I/O module converting 24 V DC to 3.45 V for FPGA configuration and level-shifting logic. IC Role / Device Role / Timing Role: Point-of-load regulator for FPGA core and interface buffers. Use Value: Integrated thermal protection prevents latch-up during sustained overload; 38 °C/W θJA enables convection-only cooling in sealed enclosures. |
| Medical Diagnostic Handheld | Test & Measurement Front-End |
Use Scenario: Battery-powered handheld ultrasound probe requiring low-noise, stable 3.45 V rail for analog beamforming ICs. IC Role / Device Role / Timing Role: Low-ripple power source for precision analog signal chain. Use Value: 1% VOUT ripple specification ensures SNR preservation in 16-bit ADC stages; no external inductor avoids magnetic interference. | Use Scenario: Benchtop multimeter with isolated digital section and analog measurement front-end sharing 3.45 V reference. IC Role / Device Role / Timing Role: Precision voltage source for analog-to-digital conversion and reference buffering. Use Value: Laser-trimmed ±1.0% output eliminates need for post-calibration trim pots; fast transient response maintains accuracy during autoranging events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar integrated switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMZ12002TZX-ADJ/NOPB | Adjustable output (0.8–6 V), 2 A, 1.2 MHz, requires external feedback resistors and 22 µF output cap | Supports multiple output voltages on same PCB; less suitable for fixed 3.45 V where BOM simplicity is critical | Choose when design flexibility across multiple voltage variants is needed; avoid if strict 3.45 V and minimal component count are priorities |
| TPS54202DDCR | 2 A, 3.45 V not available; closest fixed option is 3.3 V (TPS54202DDCT); requires external inductor and compensation | Higher pin count (6-pin SOT-23), needs external magnetics and loop compensation-increases layout complexity | Choose only if existing design already uses TPS542xx family; not drop-in for 78ST235HC due to different topology and external component requirements |
Compared with LMZ12002TZX-ADJ/NOPB and TPS54202DDCR, the 78ST235HC offers lowest system-level integration for fixed 3.45 V applications-eliminating both external inductor and feedback network while maintaining tighter output tolerance and simpler thermal management.
Availability
78ST235HC is available at Aetrix Electronics and suitable for industrial sensor nodes, PLC I/O modules, medical handheld diagnostics, and test equipment requiring stable component supply with long-term manufacturability and consistent electrical performance.
Supply support for 78ST235HC 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
Power Trends, Inc. is a U.S.-based designer and manufacturer of integrated switching regulators and DC-DC power modules, founded to deliver high-reliability, thermally robust power solutions for industrial and embedded systems.
The 78ST200 series-including 78ST235HC-is engineered for space-constrained, convection-cooled applications where external inductors are undesirable, emphasizing self-containment, protection autonomy, and laser-trimmed voltage accuracy.
FAQ
What is the required output capacitor for stable operation of the 78ST235HC?
The 78ST235HC requires a mandatory 100 µF electrolytic or tantalum output capacitor for proper operation in all applications, as explicitly stated in the datasheet. Ceramic capacitors alone are insufficient due to ESR and capacitance retention requirements under load. This value ensures loop stability, transient response compliance, and ripple suppression within the 1% VOUT specification. Using less capacitance risks oscillation, excessive overshoot, or thermal shutdown.
Does the 78ST235HC support adjustable output voltage?
No, the 78ST235HC is a fixed-output device trimmed to 3.45 V at the factory using laser calibration. It does not support external feedback adjustment. The "35" in the part number denotes the 3.45 V variant, and no resistor divider or external components can modify the output. For adjustable alternatives, consider the LMZ12002TZX-ADJ/NOPB-but note it requires additional components and layout changes.
What is the maximum allowable input voltage for the 78ST235HC?
The 78ST235HC supports an input voltage range of 7 V to 15 V when configured for 3.3–3.5 V output, as confirmed in the "Input Voltage Range" specification table. Exceeding 15 V risks permanent damage, as this is the absolute maximum rating for the internal switch. Operation below 7 V may cause dropout or regulation failure. Input transient suppression is recommended for automotive or industrial environments where voltage spikes exceed this range.
How does thermal derating affect the 78ST235HC's output current capability?
The 78ST235HC's 2 A maximum output current is rated at +25°C ambient with 40–60 LFM airflow. Above +70°C, output current must be reduced per the published thermal derating chart-e.g., to ~1.4 A at +85°C. This derating is enforced by internal thermal shutdown, which activates at junction temperatures exceeding safe limits. Board layout, copper area, and airflow directly impact actual derating behavior.
Is the 78ST235HC RoHS-compliant and lead-free?
The original 78ST235HC datasheet (Rev. 6/30/98) predates RoHS legislation and does not specify RoHS or lead-free status. Power Trends, Inc. has not published updated compliance documentation for this legacy part. For new designs requiring RoHS compliance, engineers should contact Power Trends directly or evaluate modern alternatives such as TI's LMZ12002 series, which are explicitly certified RoHS-compliant and halogen-free.
78ST235HC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 3-SIP Module
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 7V
- Voltage - Input (Max):
- 20V
- Voltage - Output (Min/Fixed):
- 3.45V
- Voltage - Output (Max):
- -
- Current - Output:
- 2A
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- -
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole, Right Angle
- Supplier Device Package:
- SIP Module-3
78ST235HC FAQ
1.How can I place an order for 78ST235HC through Aetrix?
Please submit a Request for Quotation (RFQ) for 78ST235HC 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 78ST235HC reliable?
The price and inventory of 78ST235HC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 78ST235HC is usually 5 days.
3.What payment methods are accepted for 78ST235HC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 78ST235HC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 78ST235HC?
78ST235HC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 78ST235HC 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 78ST235HC?
For technical support, including 78ST235HC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 78ST235HC requirements.
6.How does Aetrix verify that 78ST235HC is sourced from the original manufacturer or authorized distributors?
All 78ST235HC 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 78ST235HC meets industry standards.
7.What is the process for return or replacement of 78ST235HC?
All 78ST235HC units undergo pre-shipment inspection (PSI). If there is an issue with 78ST235HC, 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 78ST235HC part is unused and in its original packaging.
Return procedure for 78ST235HC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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