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STMicroelectronics ST735CD-TR
- Part No.:
- ST735CD-TR
- Manufacturer:
- STMicroelectronics
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
ST735CD-TR.pdf
- Description:
- IC REG BUCK BST -5V 200MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,596
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Product details
Overview
ST735CD-TR from STMicroelectronics is a Bi-CMOS inverting switch-mode DC-DC regulator with integrated power MOSFETs, generating a fixed -5 V output from 4.0 V to 6.2 V input. It delivers 200 mA guaranteed output current at VIN ≥ 4.5 V, features 160 kHz fixed-frequency current-mode PWM control, 75% typical efficiency, and 0.8 mA quiescent current-designed for compact HDD and portable equipment power rails.
For engineers reviewing the ST735CD-TR datasheet, ST735CD-TR pinout, ST735CD-TR application, or ST735CD-TR equivalent, key selection criteria include its inverting topology, ±5% output voltage accuracy over -40°C to +125°C, shutdown current of 10 µA, SO-8 package compatibility, and soft-start/undervoltage lockout functionality for reliable negative rail generation.
Technical Context
The ST735CD-TR implements a current-mode PWM control architecture with a factory-trimmed 160 kHz oscillator, enabling stable regulation and low noise/jitter performance. Its internal power MOSFETs eliminate external high-side switches, while the feedback loop uses an internal 1.247 V reference with 50 ppm/°C drift.
It integrates soft-start (SS pin), compensation (CC pin), and shutdown (SHDN) logic with TTL-compatible thresholds (VIL = 0.25 V, VIH = 2 V). Undervoltage lockout activates below 3.5 V input, and LX switch node supports up to 2 A peak current with 0.5 Ω typical RDS(on).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | -5 V ±5% over -40°C to +125°C; enables precise negative bias for analog ICs and op-amp rails |
| Input Voltage Range | 4.0 V to 6.2 V; compatible with single-cell Li-ion or regulated 5 V system supplies |
| Output Current | 200 mA guaranteed at VIN ≥ 4.5 V; sufficient for small-signal analog circuitry and interface ICs |
| Efficiency | 72% min at 100 mA load; reduces thermal load in space-constrained portable designs |
| Quiescent Current | 0.8 mA typical; minimizes standby power loss in battery-backed systems |
| Shutdown Current | 10 µA max; extends battery life during system sleep modes |
| Oscillator Frequency | 160 kHz fixed; simplifies EMI filtering with predictable noise spectrum |
Pinout & Package
ST735CD-TR is housed in a standard SO-8 surface-mount package (5.0 mm × 6.2 mm, 1.27 mm pitch), optimized for automated assembly and thermal performance in compact PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 SHDN | Shutdown Control Input | TTL-compatible enable: GND = shutdown (10 µA IQ), VIN = active; allows system-level power sequencing |
| 2 VREF | Internal Reference Output | 1.247 V precision reference; usable for external monitoring or auxiliary regulation |
| 3 SS | Soft-Start Timing Node | Controls output ramp-up time via external capacitor; prevents inrush current and overshoot |
| 4 CC | Compensation Network Input | Connects RC network to stabilize feedback loop; sets pole-zero placement for phase margin |
| 5 VOUT | Negative Output Terminal | Regulated -5 V supply rail; requires local ceramic output capacitor (e.g., 10 µF X7R) |
| 6 GND | Power Ground Reference | Common return path for input, output, and control circuitry; must be low-impedance plane |
| 7 LX | Switch Node Output | Drives external inductor; swings between VIN and ~-5 V; requires careful layout to minimize ringing |
| 8 VIN | Positive Input Supply | 4.0–6.2 V main power input; requires local 4.7 µF X7R decoupling capacitor |
Key Features
| Feature | Design Value |
|---|---|
| Inverting Topology with Integrated MOSFETs | Eliminates need for external high-side switch and gate driver; reduces BOM count and board area |
| Current-Mode PWM Control | Provides inherent cycle-by-cycle current limiting and fast transient response to load steps |
| Factory-Trimmed 160 kHz Oscillator | Ensures consistent switching frequency across temperature and process variation for repeatable filter design |
| Undervoltage Lockout (UVLO) | Disables operation below 3.5 V input, preventing erratic startup and brown-out behavior |
| Soft-Start Function | Gradually ramps output voltage via external capacitor on SS pin, suppressing inrush and overshoot |
Applications
| Hard Disk Drive (HDD) Preamp Bias | Portable Audio DAC Power |
|---|---|
Use Scenario: Providing stable -5 V bias for read-channel preamplifiers in 2.5-inch HDDs. IC Role / Device Role / Timing Role: Inverting DC-DC regulator generating clean negative rail from main 5 V supply. Use Value: Delivers 200 mA at ±5% accuracy over -40°C to +125°C, ensuring signal integrity in high-density storage environments. | Use Scenario: Powering dual-supply audio DACs in battery-powered portable players. IC Role / Device Role / Timing Role: Negative rail generator supporting ±5 V analog section with low noise and jitter. Use Value: 75% typical efficiency and 10 µA shutdown current extend playback time without compromising SNR. |
| Industrial Sensor Signal Conditioning | Legacy RS-232 Transceiver Supply |
Use Scenario: Generating isolated -5 V for op-amp-based bridge sensor interfaces in PLC modules. IC Role / Device Role / Timing Role: Compact inverting regulator replacing discrete charge-pump solutions. Use Value: SO-8 footprint and 0.8 mA quiescent current support low-power, wide-temperature industrial deployments. | Use Scenario: Supplying -5 V to MAX232-class RS-232 transceivers in embedded serial interfaces. IC Role / Device Role / Timing Role: Fixed-output inverter replacing inefficient transformer-based or charge-pump ICs. Use Value: 160 kHz fixed frequency enables simple LC filtering to meet RS-232 noise immunity requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar inverting DC-DC regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX764CSA+ | Fixed -5 V output, 1.2 MHz switching frequency, 125 mA output current, no integrated MOSFETs | Requires external P-channel MOSFET; higher frequency demands smaller magnetics but increases EMI risk | Prefer when board space is critical and external FET layout is acceptable |
| TPS60403DBVR | Charge-pump inverter, no inductor, 60 mA output, 90% efficiency at light loads, ±5% output accuracy | Limited output current and no adjustable soft-start; unsuitable for >100 mA analog loads | Prefer for ultra-low-noise, low-current bias where inductor-free design is mandatory |
Compared with MAX764CSA+ and TPS60403DBVR, the ST735CD-TR uniquely combines integrated MOSFETs, 200 mA capability, and 160 kHz fixed-frequency operation in SO-8-making it optimal for medium-current, noise-sensitive inverting rails where simplicity and thermal robustness are prioritized.
Availability
ST735CD-TR is available at Aetrix Electronics and suitable for hard disk drive preamp bias, portable audio DAC power, industrial sensor signal conditioning, and legacy RS-232 transceiver supply requiring stable component supply and long-term obsolescence management.
Supply support for ST735CD-TR 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power management ICs, sensors, and analog devices for automotive, industrial, and consumer markets.
The ST735 belongs to ST's legacy DC-DC converter product line, engineered specifically for compact, high-efficiency inverting power conversion in space-constrained portable and storage applications.
FAQ
What is the maximum allowable input voltage for ST735CD-TR?
The absolute maximum DC input voltage (VIN to GND) is +7 V per the datasheet Absolute Maximum Ratings table. Operation above 6.2 V is not specified and risks exceeding internal MOSFET breakdown limits or degrading long-term reliability. For continuous operation, maintain VIN within 4.0 V to 6.2 V as characterized in Electrical Characteristics.
Can ST735CD-TR be used to generate voltages other than -5 V?
No. The ST735CD-TR is a fixed-output inverting regulator with internal feedback resistor network trimmed for -5 V ±5%. It lacks external feedback pins or adjustment capability. For adjustable negative outputs, consider the ST736 or discrete controller-based designs with external resistive dividers.
Is an external inductor required, and what value is recommended?
Yes-an external inductor is mandatory. The typical application circuit specifies a 10 µH shielded power inductor rated for ≥2 A saturation current. Inductor DCR must be minimized to preserve efficiency, and core material should support 160 kHz operation with low AC losses (e.g., ferrite or metal composite).
Does ST735CD-TR support synchronous rectification?
No. The ST735CD-TR uses a single internal N-channel MOSFET driving the LX node into an external diode-based rectifier (as shown in the schematic diagram). It does not integrate or support a synchronous rectifier FET; the output stage relies on a Schottky or fast-recovery diode for flyback conduction.
ST735CD-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Negative
- Topology:
- Buck-Boost
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 6.2V
- Voltage - Output (Min/Fixed):
- -5V
- Voltage - Output (Max):
- -
- Current - Output:
- 200mA
- Frequency - Switching:
- 160kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
ST735CD-TR FAQ
1.How can I place an order for ST735CD-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for ST735CD-TR 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 ST735CD-TR reliable?
The price and inventory of ST735CD-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ST735CD-TR is usually 5 days.
3.What payment methods are accepted for ST735CD-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ST735CD-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ST735CD-TR?
ST735CD-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ST735CD-TR 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 ST735CD-TR?
For technical support, including ST735CD-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ST735CD-TR requirements.
6.How does Aetrix verify that ST735CD-TR is sourced from the original manufacturer or authorized distributors?
All ST735CD-TR 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 ST735CD-TR meets industry standards.
7.What is the process for return or replacement of ST735CD-TR?
All ST735CD-TR units undergo pre-shipment inspection (PSI). If there is an issue with ST735CD-TR, 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 ST735CD-TR part is unused and in its original packaging.
Return procedure for ST735CD-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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