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Vishay Siliconix SI9145BY-E3
- Part No.:
- SI9145BY-E3
- Manufacturer:
- Vishay Siliconix
- Category:
- DC DC Switching Controllers
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SI9145BY-E3.pdf
- Description:
- IC REG CTRLR BUCK/BOOST 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,509
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Product details
Overview
SI9145BY-E3 from Vishay Siliconix is a low-voltage voltage-mode PWM switchmode controller IC designed for high-efficiency DC/DC converters in battery-powered systems. It operates from 2.7 V to 7 V, features a 1.5 V ±1.5% precision bandgap reference, supports up to 2 MHz oscillator frequency via external ROSC/COSC, delivers ±130 mA peak output drive, and enables programmable maximum duty cycle (0–100%) via DMAX/SS pin for boost or buck topologies.
For engineers reviewing the SI9145BY-E3 datasheet, SI9145BY-E3 pinout, SI9145BY-E3 application, or SI9145BY-E3 equivalent, key selection criteria include input voltage range compatibility with NiCd/NiMH/Li-ion batteries, MODE SELECT polarity configuration for external MOSFET drive, DMAX/SS-based soft-start and duty-cycle limiting, and industrial-temperature (−25 °C to +85 °C) SOIC-16 packaging.
Technical Context
The SI9145BY-E3 implements conventional voltage-mode PWM control with an internal error amplifier (55 dB open-loop gain, 10 MHz unity-gain bandwidth), a 2-MHz-capable oscillator using external ROSC (5 kΩ–250 kΩ) and COSC (47 pF–200 pF), and UVLO with 1.2 V threshold and 200 mV hysteresis. Its COMP pin drives the PWM comparator while FB/NI form a feedback loop referenced to the 1.5 V internal VREF.
It supports dual topology operation via MODE SELECT: when tied to VDD, it enables DMAX/SS-controlled duty-cycle limiting for boost/flyback; when grounded, it disables limiting for buck configurations driving p-channel MOSFETs. The OUTPUT pin provides CMOS push-pull drive (130 mA sink / 180 mA source at VDD = 2.7 V) referenced to VS, with PGND separate from signal GND.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7 V to 7 V - supports single-cell Li-ion (3.0–4.2 V), NiMH (2.7–4.2 V), and regulated 3.3/5 V rails without external LDO. |
| Oscillator Frequency | 2 kHz to 2 MHz - externally programmable via ROSC/COSC; enables optimization of efficiency vs. size in inductor/capacitor selection. |
| Voltage Reference | 1.5 V ±1.5% - trimmed bandgap reference used for FB regulation and ROSC current generation; stable over temperature and supply. |
| Output Drive Capability | ±130 mA (sink/source at VDD = 2.7 V) - directly drives gate of medium-size discrete MOSFETs without buffer stage in low-power SMPS. |
| Duty Cycle Control | 0–100% programmable via DMAX/SS voltage (1.0–1.5 V typical range) - enables soft-start, overcurrent protection, and topology-specific limit tuning. |
| Supply Current | 1.1 mA typical (normal mode), 250 µA (standby) - extends battery life in portable devices during idle or sleep states. |
| Operating Temperature | −25 °C to +85 °C - qualified for industrial environments including handheld instruments and automotive body electronics. |
Pinout & Package
SI9145BY-E3 is packaged in a 16-pin SOIC (Narrow, MS-012 compliant) with 1.27 mm pitch, 10.0 mm × 4.0 mm body, and exposed thermal pad not present. Pin 1 is VDD; pin 16 is VS; pin 15 is OUTPUT; pin 8 is GND; pin 14 is PGND - critical separation of power and signal grounds for noise immunity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD (Pin 1) | Logic & analog supply rail | Powers internal circuitry except output driver; requires ≥0.1 µF bypass capacitor to GND for stability. |
| MODE SELECT (Pin 2) | Topology configuration input | High = DMAX/SS active (boost/flyback); Low = unlimited duty cycle (buck with p-MOS); sets OUTPUT polarity logic. |
| DMAX/SS (Pin 3) | Duty-cycle limit control | Analog input (1.0–1.5 V) scaling max PWM on-time; also supports RC soft-start by charging through resistor. |
| COMP (Pin 4) | Error amplifier output | Drives PWM comparator; connects to FB via Type II/III compensation network for loop stability. |
| FB (Pin 5) | Inverting error amp input | Connects to resistor divider from regulated output; compares against 1.5 V VREF to maintain regulation. |
| NI (Pin 6) | Non-inverting error amp input | Internally tied to VREF in standard use; enables differential sensing if externally biased. |
| VREF (Pin 7) | 1.5 V reference output | Stable, low-noise reference for FB and ROSC current source; load >150 kΩ recommended. |
| GND (Pin 8) | Signal ground return | Reference for VDD, UVLOSET, ENABLE, MODE SELECT, COMP, FB, NI, ROSC, COSC, OTS. |
| ROSC (Pin 9) | Oscillator timing resistor node | 1.0 V source driving external resistor to GND; sets charging current for COSC triangle waveform. |
| COSC (Pin 10) | Oscillator timing capacitor node | External capacitor (47–200 pF) charged/discharged by ROSC-derived current; determines fOSC. |
| OTS (Pin 11) | Over-temperature flag output | Open-drain low-active signal at 150 °C junction trip; latched until ENABLE toggled or power cycled. |
| ENABLE (Pin 12) | Global operation enable | Active-high digital input; forces standby mode (oscillator off, OUTPUT held) when low. |
| UVLOSET (Pin 13) | Under-voltage lockout monitor | Monitors external voltage divider; enters standby if <1.2 V (200 mV hysteresis) to prevent brownout operation. |
| PGND (Pin 14) | Power ground return | Return path for VS supply and OUTPUT driver; must be routed separately from GND to minimize noise coupling. |
| OUTPUT (Pin 15) | CMOS push-pull PWM output | Drives external MOSFET gate; sinks 150 mA / sources 130 mA at VDD = 2.7 V; level-shifting required for n-MOS high-side. |
| VS (Pin 16) | Driver supply rail | Separate supply for OUTPUT stage; allows bootstrapped or isolated gate drive; bypass capacitor required. |
Key Features
| Feature | Design Value |
|---|---|
| Voltage-mode PWM architecture | Enables predictable loop compensation using standard Type II/III networks; avoids subharmonic oscillation in continuous conduction mode. |
| Programmable 0–100% duty cycle | Supports both step-up (boost) and step-down (buck) topologies via MODE SELECT and DMAX/SS analog control - no external logic needed. |
| 200 mA peak output drive | Directly switches medium-current MOSFETs (e.g., Si7157DP, Si7850DP) without gate driver IC, reducing BOM count and layout area. |
| Integrated 1.5 V ±1.5% reference | Eliminates need for external reference IC; provides stable bias for feedback divider and ROSC current source across temperature and line. |
| Standby mode with 250 µA IQ | Reduces quiescent consumption by >99% vs. active mode - critical for battery runtime in always-on sensor nodes or wearables. |
| Separate VS and PGND pins | Isolates high-current switching paths from sensitive analog circuitry, improving noise immunity and regulation accuracy in noisy PCB environments. |
Applications
| Portable Medical Devices | Industrial Handheld Instruments |
|---|---|
|
Use Scenario: Powering LED backlight and microcontroller rails from single Li-ion cell in pulse oximeters or glucose meters. IC Role / Device Role / Timing Role: Primary PWM controller regulating 3.3 V and 5 V outputs via synchronous buck and boost stages. Use Value: 2.7 V start-up and 250 µA standby current extend battery life beyond 72 hours per charge; MODE SELECT simplifies dual-rail design. |
Use Scenario: Generating isolated 12 V bias for analog front-end and 3.3 V for ARM Cortex-M MCU in battery-operated multimeters. IC Role / Device Role / Timing Role: Controller for flyback converter (MODE SELECT = VDD) and buck post-regulator (MODE SELECT = GND). Use Value: DMAX/SS pin enables precise overvoltage protection on 12 V rail; UVLOSET monitors main battery health before enabling conversion. |
| Wireless Sensor Nodes | Automotive Body Electronics |
|
Use Scenario: Supplying 1.8 V to BLE SoC and 3.3 V to environmental sensors from two-series NiMH pack (2.4–3.0 V). IC Role / Device Role / Timing Role: Boost controller with soft-start (RC on DMAX/SS) and ENABLE-controlled wake-up sequencing. Use Value: 2.7 V minimum operating voltage ensures full functionality down to end-of-discharge; OTS pin prevents thermal runaway in sealed enclosures. |
Use Scenario: Regulating 5 V for LIN transceiver and 3.3 V for microcontroller in door module powered by 12 V battery with wide cold-crank dips. IC Role / Device Role / Timing Role: Buck controller (MODE SELECT = GND) with UVLOSET tied to battery monitor for brownout detection. Use Value: −25 °C to +85 °C rating meets automotive interior temp spec; separate PGND/GND reduces EMI coupling into CAN/LIN signal paths. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switchmode controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3481MM/NOPB | Current-mode control; wider 2.9–40 V input; no integrated VREF; requires external reference for FB. | Better suited for high-input-voltage boost/buck-boost; lacks DMAX/SS soft-start and MODE SELECT flexibility. | Choose LM3481MM/NOPB for >12 V input or current-sense-based protection; SI9145BY-E3 preferred for <7 V battery systems needing analog duty control. |
| TPS40210DRCT | Current-mode controller; 4.5–52 V input; integrated gate driver; no standby mode; higher IQ (2.5 mA). | Targeted at industrial DC/DC with high-side n-MOS; lacks low-voltage start-up and ultra-low-IQ standby. | Use TPS40210DRCT for high-efficiency 24 V–48 V supplies; SI9145BY-E3 remains optimal for compact, low-IQ, sub-7 V designs. |
Compared with LM3481MM/NOPB and TPS40210DRCT, the SI9145BY-E3 uniquely combines sub-3 V start-up, 250 µA standby, programmable 0–100% duty cycle, and dual-topology support in a single SOIC-16 package - making it irreplaceable for space-constrained, battery-sensitive applications where input voltage stays below 7 V.
Availability
SI9145BY-E3 is available at Aetrix Electronics and suitable for portable medical devices, industrial handheld instruments, wireless sensor nodes, and automotive body electronics requiring stable component supply and long-term industrial temperature support.
Supply support for SI9145BY-E3 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
Vishay Siliconix is a global leader in discrete semiconductors and passive components, specializing in high-reliability power management solutions for industrial, automotive, and computing markets.
The SI9145BY-E3 belongs to Vishay's low-voltage PWM controller product line, engineered specifically for energy-efficient DC/DC conversion in battery-powered equipment where start-up voltage, quiescent current, and topology flexibility are critical.
FAQ
What is the minimum input voltage required for SI9145BY-E3 to start switching?
The SI9145BY-E3 has a minimum start-up voltage of 3.0 V, verified under test conditions with VDD = VS and COSC = 100 pF. Once started, it continues operating down to 2.7 V. This ensures reliable turn-on from partially discharged NiMH or Li-ion cells while maintaining regulation across the full discharge curve. The UVLOSET pin can be configured to override this behavior for custom brownout thresholds.
How does the MODE SELECT pin affect the SI9145BY-E3 output polarity and duty-cycle behavior?
When MODE SELECT is tied to VDD, the SI9145BY-E3 enables DMAX/SS-based duty-cycle limiting (0–100%) and drives OUTPUT high to turn on n-channel MOSFETs in boost/flyback topologies. When MODE SELECT is grounded, duty-cycle limiting is disabled and OUTPUT goes low to drive p-channel MOSFETs in buck configurations - eliminating need for external level shifters or inverters in either case.
Can SI9145BY-E3 be used in a synchronous buck converter, and what external components are required?
Yes, the SI9145BY-E3 supports synchronous buck operation when MODE SELECT = GND. It requires an external high-side p-MOS and low-side n-MOS (or Schottky diode), plus feedback resistors to set output voltage via FB/VREF, a compensation network between COMP and FB, and ROSC/COSC to set switching frequency. No external reference or driver IC is needed due to its integrated 1.5 V VREF and ±130 mA OUTPUT drive.
What is the purpose of the separate PGND and GND pins on the SI9145BY-E3, and how should they be routed?
The SI9145BY-E3 separates PGND (Pin 14) for high-current OUTPUT and VS return from GND (Pin 8) for low-noise analog and logic circuits. PGND must connect directly to the source of the power MOSFET and the negative terminal of the output capacitor, while GND ties to VREF, FB, COMP, and all logic inputs. A single-point star ground connection between PGND and GND near the IC minimizes noise coupling and improves regulation accuracy.
Does SI9145BY-E3 provide over-temperature protection, and how is it implemented?
Yes, the SI9145BY-E3 includes integrated over-temperature protection with a 150 °C trip point. When junction temperature exceeds this threshold, the OTS pin (Pin 11) pulls low and latches until ENABLE is toggled (low→high) or power is cycled. This prevents thermal damage during overload or poor heatsinking. The OTS signal can feed into system-level fault monitoring or disable downstream circuitry via external logic.
SI9145BY-E3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay Siliconix
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Output Type:
- Transistor Driver
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck, Boost
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 2.7V ~ 7V
- Frequency - Switching:
- 2kHz ~ 2MHz
- Duty Cycle (Max):
- 100%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Soft Start
- Operating Temperature:
- -25°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
SI9145BY-E3 FAQ
1.How can I place an order for SI9145BY-E3 through Aetrix?
Please submit a Request for Quotation (RFQ) for SI9145BY-E3 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 SI9145BY-E3 reliable?
The price and inventory of SI9145BY-E3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SI9145BY-E3 is usually 5 days.
3.What payment methods are accepted for SI9145BY-E3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI9145BY-E3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SI9145BY-E3?
SI9145BY-E3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SI9145BY-E3 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 SI9145BY-E3?
For technical support, including SI9145BY-E3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI9145BY-E3 requirements.
6.How does Aetrix verify that SI9145BY-E3 is sourced from the original manufacturer or authorized distributors?
All SI9145BY-E3 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 SI9145BY-E3 meets industry standards.
7.What is the process for return or replacement of SI9145BY-E3?
All SI9145BY-E3 units undergo pre-shipment inspection (PSI). If there is an issue with SI9145BY-E3, 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 SI9145BY-E3 part is unused and in its original packaging.
Return procedure for SI9145BY-E3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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