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Microchip Technology MIC3172BM-TR
- Part No.:
- MIC3172BM-TR
- Manufacturer:
- Microchip Technology
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MIC3172BM-TR.pdf
- Description:
- IC REG BUCK BOOST 1.25A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,488
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Product details
Overview
MIC3172BM-TR from Microchip Technology is a 100 kHz current-mode PWM controller IC with integrated 65 V / 1.25 A NPN power switch, designed for step-up, step-down, inverting, and flyback topologies. It features TTL-compatible enable/shutdown control (EN pin), 3 V to 40 V input range, 7 mA operating quiescent current, and <1 µA shutdown current-enabling efficient battery-powered DC/DC conversion in handheld instruments and low-power off-line supplies.
For engineers reviewing the MIC3172BM-TR datasheet, MIC3172BM-TR pinout, MIC3172BM-TR application, or MIC3172BM-TR equivalent, key selection criteria include its dedicated EN pin for precise on/off control, dual power ground terminals (PGND1/PGND2) enabling current limit scaling, internal cycle-by-cycle current limiting, and compatibility with LT1172 socket layouts in legacy designs.
Technical Context
The MIC3172BM-TR implements fixed-frequency (88–112 kHz) current-mode PWM control using an internal 1.24 V reference and transconductance error amplifier. Its floating switch architecture supports boost, buck, inverting, Cuk, and flyback configurations without external level-shifting components.
Control logic includes anti-saturation circuitry for extended duty cycle, internal 2.3 V bias regulator, and TTL-level EN input with 0.4–2.4 V threshold. The COMP pin provides high-impedance transconductance output for loop compensation, soft-start, and current-limit tailoring-enabling stable regulation across wide input/output ranges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Rating | 65 V breakdown voltage, 1.25 A guaranteed current limit at 50% duty cycle - supports up to 50 W off-line converters with external switch or direct low-power regulation. |
| Input Voltage Range | 3.0 V to 40 V - enables operation from single Li-ion cells to industrial 24 V rails and universal AC/DC adapter outputs. |
| Oscillator Frequency | 88–112 kHz typical (100 kHz nominal) - balances EMI suppression and magnetics size; no external timing components required. |
| Quiescent Current | 7 mA operating, <1 µA shutdown - extends battery life in portable devices and enables zero-power standby states. |
| Enable Threshold | VEN_TH = 0.4–2.4 V - ensures robust TTL/CMOS compatibility; EN must be tied high to VIN if unused. |
| Feedback Reference | VFB = 1.224–1.264 V - sets output voltage via external resistor divider; ±0.02 V tolerance enables ≤1% output regulation accuracy. |
| Thermal Range | –40°C to +85°C ambient - qualified for industrial and automotive cabin environments without derating. |
Pinout & Package
Package: 8-pin SOIC (M suffix), surface-mount, RoHS-compliant, 120°C/W junction-to-ambient thermal resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SGND) | Signal Ground | Analog reference for error amplifier and feedback; must connect directly to input capacitor ground-separate from power grounds to avoid noise coupling. |
| 2 (COMP) | Error Amplifier Output | Transconductance output (3.9 µA/mV typical); used for loop compensation, soft-start, or current limit clamping-high impedance allows easy external control. |
| 3 (FB) | Inverting Feedback Input | Connects to resistive divider from output; 310–750 nA bias current enables high-value dividers for low power consumption. |
| 4 (EN) | Enable Control | TTL-compatible digital input: high ≥2.0 V enables switching; low ≤0.4 V disables regulator and reduces supply current to <1 µA. |
| 5 (VIN) | Power Supply Input | 3–40 V primary supply; powers internal regulators and driver-minimum 2.7 V start-up enables deep battery discharge operation. |
| 6 (PGND2) | Power Ground #2 | Emitter of internal NPN switch with 0.3 Ω sense resistor; required connection point for inductor or input ground in most topologies. |
| 7 (VSW) | Switch Collector | High-side collector node of internal 1.25 A NPN transistor; connects to inductor (boost), transformer primary (flyback), or output diode (buck). |
| 8 (PGND1) | Power Ground #1 | Second emitter terminal; optional connection-floating reduces current limit by 2×, useful for lower-power designs or fault-current limiting. |
Key Features
| Feature | Design Value |
|---|---|
| Dedicated EN pin | Enables deterministic system-level power sequencing and ultra-low leakage shutdown (<1 µA), eliminating need for external MOSFET gate drivers or logic-level translators. |
| Floating switch architecture | Supports all major non-isolated topologies (boost/buck/inverting) and isolated flyback without external level shifters-reducing BOM count and layout complexity. |
| Internal cycle-by-cycle current limit | Guarantees 1.25 A peak switch current at 50% duty cycle; prevents destructive overcurrent events during startup, short-circuit, or transient load conditions. |
| Low external parts count | Requires only inductor, diode, output capacitor, and two feedback resistors-no external oscillator, timing capacitor, or current-sense resistor needed. |
| LT1172 socket compatibility | Pin-for-pin compatible with Linear Technology LT1172 in 8-pin DIP/SOIC packages-enables drop-in replacement in legacy designs with minimal board modification. |
Applications
| Laptop/Palmtop Power Management | Handheld Instrument DC/DC Conversion |
|---|---|
Use Scenario: Generating regulated 12 V from a 5 V USB or Li-ion source in compact portable test equipment. IC Role / Device Role / Timing Role: Primary current-mode PWM controller with integrated switch, managing energy transfer via flyback topology. Use Value: Eliminates external MOSFET and gate driver, reducing solution size by >30% while maintaining <1 µA shutdown current for long shelf life. | Use Scenario: Boosting 3.3 V MCU rail to 5 V for analog front-end sensors and display drivers in battery-powered multimeters. IC Role / Device Role / Timing Role: Step-up controller operating at 100 kHz to minimize inductor size and audible noise in sensitive measurement environments. Use Value: 7 mA quiescent current extends single-cell alkaline battery life beyond 100 hours of active use; EN pin enables MCU-controlled power gating. |
| Off-Line 50 W Converter (with External Switch) | Predriver for Higher-Power SMPS Stages |
Use Scenario: Controlling external 650 V MOSFET in 50 W AC/DC adapter where primary-side regulation is required. IC Role / Device Role / Timing Role: Master controller providing PWM drive signals and current sensing interface to external power stage. Use Value: Internal 1.24 V reference and transconductance COMP output simplify feedback design; PGND1/PGND2 separation improves current-sense accuracy. | Use Scenario: Driving gate of high-current external N-channel MOSFET in high-efficiency 100 W DC/DC module for industrial PLC I/O modules. IC Role / Device Role / Timing Role: Low-side predriver with fast turn-on/turn-off capability enabled by anti-saturation circuitry and 100 kHz fixed frequency. Use Value: Reduces gate drive losses vs. discrete transistor drivers; EN pin synchronizes power stage enable with system boot sequence. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PWM controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1172CN8#PBF | No dedicated EN pin; shutdown achieved by pulling VC (COMP) below 0.15 V-requires external transistor or logic gate. | Legacy designs without digital enable control; less suitable for MCU-managed power sequencing. | Select LT1172CN8#PBF only when reusing existing LT1172 PCB footprints without EN signal routing. |
| TPS61040DRBR | Higher 500 kHz switching frequency, 28 V max input, integrated 0.5 A switch-lower power, smaller magnetics, but no PGND1/PGND2 flexibility. | Battery-powered consumer electronics requiring ultra-compact footprint and higher efficiency at light loads. | Choose TPS61040DRBR for new space-constrained designs under 15 W; MIC3172BM-TR preferred for industrial 40 V input and programmable current limiting. |
Compared with LT1172CN8#PBF, MIC3172BM-TR adds deterministic TTL-enable functionality and eliminates external shutdown circuitry; versus TPS61040DRBR, it trades higher frequency for wider input range, higher switch current, and topology flexibility-making it optimal for ruggedized, medium-power industrial DC/DC stages.
Availability
MIC3172BM-TR is available at Aetrix Electronics and suitable for laptop/palmtop computers, handheld instruments, and off-line converter applications requiring stable component supply, long-term lifecycle support, and industrial temperature qualification.
Supply support for MIC3172BM-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
Microchip Technology is a global semiconductor company specializing in microcontrollers, analog devices, and power management ICs, with a focus on reliability, longevity, and embedded system integration.
The MIC3172 product line delivers highly integrated, thermally robust PWM controllers for medium-power DC/DC conversion in industrial, medical, and portable equipment-designed to replace discrete switcher solutions while maintaining design flexibility.
FAQ
What is the maximum input voltage rating for the MIC3172BM-TR?
The MIC3172BM-TR has an absolute maximum input voltage (VIN) rating of 40 V. Operation above this voltage risks permanent damage. For reliable continuous operation, the recommended input range is 3.0 V to 40 V, with minimum start-up voltage of 2.7 V. This makes MIC3172BM-TR suitable for 24 V industrial rails and universal AC/DC adapter outputs while retaining compatibility with single-cell Li-ion systems.
How does the EN pin function on the MIC3172BM-TR?
The EN pin on the MIC3172BM-TR is a TTL-compatible digital enable input: applying ≥2.0 V (TTL high) enables normal switching operation, while ≤0.4 V (TTL low) places the device in shutdown mode, reducing quiescent current to <1 µA. If unused, EN must be tied directly to VIN or a logic-high source-floating EN is not permitted. This feature enables precise system-level power sequencing in battery-powered MIC3172BM-TR applications.
Can the MIC3172BM-TR be used in buck (step-down) configurations?
Yes, the MIC3172BM-TR supports buck topology due to its floating switch architecture and dual power ground terminals (PGND1 and PGND2). In buck mode, VSW connects to the input rail, PGND2 to the inductor, and the output is taken between inductor and diode. The internal 1.25 A switch and cycle-by-cycle current limiting ensure safe operation-though external diode and inductor selection must meet buck-specific RMS/peak current requirements for the target MIC3172BM-TR application.
What is the purpose of the two power ground pins (PGND1 and PGND2) on the MIC3172BM-TR?
PGND2 is the primary emitter connection for the internal NPN switch and is required in all configurations. PGND1 is an auxiliary emitter terminal with a series 0.3 Ω current-sense resistor; leaving it unconnected reduces the effective current limit by approximately 2×-providing a simple hardware method to scale peak switch current for lower-power designs or enhanced fault protection. Both pins must be routed to low-impedance ground planes, but kept separate from SGND to preserve analog accuracy in the MIC3172BM-TR feedback path.
Is the MIC3172BM-TR pin-compatible with the LT1172?
Yes-the MIC3172BM-TR is pin-compatible with the LT1172 in 8-pin DIP and SOIC packages, including identical pin numbering and functional mapping (e.g., FB, COMP, VSW, GND). However, the MIC3172BM-TR replaces the LT1172's VC (voltage control) shutdown method with a dedicated EN pin. Adapting requires connecting EN to VIN for always-on operation or adding a logic gate for controlled shutdown-details are provided in Microchip's DS20006208A Section 5.2 for seamless MIC3172BM-TR migration.
MIC3172BM-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Function:
- Step-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost, Cuk, Flyback, Forward Converter
- Output Type:
- -
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- -
- Current - Output:
- 1.25A
- Frequency - Switching:
- 100kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MIC3172BM-TR FAQ
1.How can I place an order for MIC3172BM-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for MIC3172BM-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 MIC3172BM-TR reliable?
The price and inventory of MIC3172BM-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MIC3172BM-TR is usually 5 days.
3.What payment methods are accepted for MIC3172BM-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MIC3172BM-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MIC3172BM-TR?
MIC3172BM-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MIC3172BM-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 MIC3172BM-TR?
For technical support, including MIC3172BM-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MIC3172BM-TR requirements.
6.How does Aetrix verify that MIC3172BM-TR is sourced from the original manufacturer or authorized distributors?
All MIC3172BM-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 MIC3172BM-TR meets industry standards.
7.What is the process for return or replacement of MIC3172BM-TR?
All MIC3172BM-TR units undergo pre-shipment inspection (PSI). If there is an issue with MIC3172BM-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 MIC3172BM-TR part is unused and in its original packaging.
Return procedure for MIC3172BM-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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