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Microchip Technology MIC3172YM
- Part No.:
- MIC3172YM
- Manufacturer:
- Microchip Technology
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MIC3172YM.pdf
- Description:
- IC REG BUCK BOOST 1.25A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:877
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Product details
Overview
MIC3172YM 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 operates from 3 V to 40 V input, delivers up to 50 W with external switch, and features TTL-compatible enable/shutdown control (EN pin), <1 µA shutdown quiescent current, and internal cycle-by-cycle current limiting - used in handheld instruments and off-line converters.
For engineers reviewing the MIC3172YM datasheet, MIC3172YM pinout, MIC3172YM application, or MIC3172YM equivalent, key selection criteria include its 1.25 A internal switch rating, EN-controlled on/off functionality, 100 kHz fixed-frequency operation, dual power ground pins (PGND1/PGND2) enabling current limit scaling, and compatibility with LT1172 sockets in retrofit designs.
Technical Context
The MIC3172YM implements current-mode control using an internal transconductance error amplifier (3.9 µA/mV typical transconductance), 1.24 V precision reference, and 100 kHz oscillator with ±12% tolerance. Its floating switch architecture supports boost, buck, inverting, Cuk, and isolated flyback configurations without topology-specific reconfiguration.
It integrates anti-saturation circuitry to extend duty cycle range and uses dual emitter-ground pins (PGND1 and PGND2) - connecting PGND1 reduces current limit by 50%, enabling flexible output current tailoring. The EN pin accepts TTL-level logic (0.4 V low threshold, 2.4 V high threshold) and draws ≤1 µA in shutdown.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Rating | 65 V breakdown voltage, 1.25 A guaranteed current limit at 50% duty cycle - enables direct replacement of discrete switch in 50 W off-line flyback designs. |
| Input Voltage Range | 3.0 V to 40 V - supports wide-input battery-powered systems (e.g., 4–6 V palmtop supplies) and industrial 24 V rails. |
| Oscillator Frequency | 88–112 kHz (typ. 100 kHz) - fixed frequency simplifies EMI filtering; no external timing components required. |
| Quiescent Current | 7 mA operating, <1 µA shutdown - extends battery life in handheld instruments during standby. |
| Feedback Reference | 1.240 V ±24 mV - sets output voltage via resistive divider; line regulation ≤0.07 %/V ensures stability across input range. |
| Enable Threshold | VEN_TH = 0.4–2.4 V - compatible with standard TTL/CMOS logic; EN must be tied high to VIN if unused. |
| Thermal Range | –40°C to +85°C ambient - validated for industrial embedded use; junction max +125°C. |
Pinout & Package
Package: 8-pin SOIC (Y suffix per Microchip ordering guide; YM denotes SOIC-8, –40°C to +85°C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SGND) | Signal Ground | Analog reference ground for error amplifier and feedback; must be separated from power grounds to avoid noise coupling into regulation loop. |
| 2 (COMP) | Error Amplifier Output | Transconductance-type compensation node; used for loop stabilization, soft-start, or current limit clamping - high-impedance output allows external RC or diode-capacitor networks. |
| 3 (FB) | Inverting Feedback Input | Connects to resistive divider from output; senses regulated voltage; bias current ≤750 nA minimizes divider loading error. |
| 4 (EN) | Enable Control Input | 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) | Main Supply Input | 3–40 V DC input powering internal regulators and driver; minimum start-up voltage is 2.7 V. |
| 6 (PGND2) | Power Ground #2 | Primary emitter connection for internal NPN switch; required connection point for inductor or input ground return path. |
| 7 (VSW) | Switch Collector | High-side collector node connected to inductor or transformer primary; handles full switched current and 65 V transient spikes. |
| 8 (PGND1) | Power Ground #1 | Secondary emitter connection; when left open, reduces current limit by 50%; when shorted to PGND2, enables full 1.25 A capability. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 65 V / 1.25 A NPN Switch | Eliminates external transistor in ≤50 W flyback or boost converters; reduces BOM count and layout complexity. |
| TTL-Compatible Enable (EN) Pin | Enables system-level power sequencing and sleep mode control without external level-shifting circuitry. |
| Dual Power Ground Pins (PGND1/PGND2) | Allows hardware-selectable current limit reduction (50%) by leaving PGND1 unconnected - supports scalable output power design. |
| Current-Mode Control Architecture | Provides inherent cycle-by-cycle current limiting, simplified loop compensation, and automatic input voltage feed-forward for stable regulation under line transients. |
| Anti-Saturation Circuitry | Reduces stored charge in internal NPN switch, extending usable duty cycle range and improving efficiency in high-duty applications. |
Applications
| Handheld Instruments | Laptop/Palmtop Computers |
|---|---|
Use Scenario: Portable multimeters and oscilloscopes requiring isolated 5 V or ±12 V rails from single-cell Li-ion (3.0–4.2 V) or 4 AA battery (4.8–6.0 V) inputs. IC Role / Device Role / Timing Role: Primary flyback controller generating isolated auxiliary supplies; EN pin synchronized with MCU sleep/wake cycles. Use Value: <1 µA shutdown current preserves battery charge during idle; 100 kHz fixed frequency enables compact magnetics and predictable EMI signature. | Use Scenario: USB-C PD adapter auxiliary supply or LCD backlight boost converter in sub-notebook platforms. IC Role / Device Role / Timing Role: Step-up controller delivering 12 V @ 250 mA from 5 V USB bus; operates in discontinuous conduction mode for light-load efficiency. Use Value: Integrated 1.25 A switch eliminates external MOSFET and gate driver; SGND/PGND separation ensures clean analog sensing for accurate voltage regulation. |
| Off-Line Converters (≤50 W) | Predriver for Higher Power Capability |
Use Scenario: AC-DC offline flyback converters powering IoT gateways or smart home hubs with universal 85–265 VAC input (via bridge rectifier + bulk cap). IC Role / Device Role / Timing Role: Primary-side controller driving transformer primary; EN pin used for brown-out protection latch-off. Use Value: 65 V switch rating accommodates reflected flyback voltage plus leakage spike margin; thermal resistance of 120°C/W (SOIC) supports convection-cooled designs. | Use Scenario: Gate driver pre-regulator stage feeding high-current synchronous buck controllers in motor drive or PoE injectors. IC Role / Device Role / Timing Role: High-efficiency predriver supplying stable 5 V or 12 V gate drive rail to external high-side FET drivers. Use Value: Low 7 mA quiescent current minimizes no-load losses; COMP pin allows precise current limit tuning to match downstream driver requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PWM controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1172CS8#PBF | Fixed 100 kHz frequency, no enable pin; shutdown requires VC pin pulled below 0.15 V; 60 V switch rating, 1.25 A current limit. | Legacy socket-compatible but lacks dedicated EN control; requires external circuitry for TTL-compatible shutdown. | Select when replacing existing LT1172 designs without modifying control logic; not suitable for new designs requiring clean enable signaling. |
| TPS61088RHLR | 1.5 A integrated switch, 2.7–12 V input, 2.5–18 V output, 570 kHz switching, I²C programmable, no EN pin - synchronous boost only. | Higher frequency enables smaller inductors/caps but limited to boost topology; no flyback or buck capability. | Select for space-constrained battery-powered boost applications needing higher efficiency; not a functional substitute for multi-topology or flyback use cases. |
Compared with LT1172CS8#PBF, MIC3172YM adds dedicated TTL-enable and improved 65 V switch rating; compared with TPS61088RHLR, it supports flyback/buck/inverting topologies and offers lower-frequency EMI management - making MIC3172YM optimal for industrial and retrofit designs requiring flexibility and robustness.
Availability
MIC3172YM is available at Aetrix Electronics and suitable for handheld instruments, off-line converters, and laptop/palmtop computers requiring stable component supply, long-term lifecycle support, and drop-in compatibility with legacy LT1172-based designs.
Supply support for MIC3172YM 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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and power management ICs, with broad industrial and automotive qualification coverage.
The MIC3172YM belongs to Microchip's legacy high-voltage PWM controller product line, engineered for cost-sensitive, multi-topology DC-DC conversion in portable and industrial power supplies where integration, reliability, and socket compatibility are critical.
FAQ
What is the maximum output power achievable with the MIC3172YM in a flyback configuration?
The MIC3172YM supports up to 50 W in off-line flyback converters when used with an external power switch. With its internal 65 V / 1.25 A NPN switch, practical output power is limited to ~15–20 W depending on topology, duty cycle, and thermal design. For example, in a 5 V to 12 V flyback with 4–6 V input, MIC3172YM delivers 5 V @ 0.25 A reliably. Full 50 W requires external MOSFET driven by MIC3172YM's VSW node.
Can the MIC3172YM replace the LT1172 in existing designs without PCB changes?
Yes - the MIC3172YM fits most LT1172 sockets mechanically and electrically. Pin-for-pin compatible except that LT1172 pin 2 (VC) maps to MIC3172YM pin 4 (EN). For non-shutdown circuits, tie EN to VIN; for shutdown, connect EN to existing logic control. No layout changes are required, and the MIC3172YM's higher 65 V switch rating improves robustness over LT1172's 60 V rating.
How does the dual PGND pin configuration affect current limiting in the MIC3172YM?
PGND1 and PGND2 are the two emitters of the internal NPN switch. Leaving PGND1 unconnected disables half the current sense path, reducing the effective current limit to ~0.625 A (50% of 1.25 A). Shorting PGND1 to PGND2 enables full 1.25 A current capability. This hardware-selectable scaling allows one MIC3172YM design to support multiple output power levels without firmware or component changes.
What is the purpose of the SGND pin on the MIC3172YM, and how should it be routed?
SGND is the dedicated signal ground for the internal error amplifier, reference, and feedback circuitry. It must be connected directly to the input filter capacitor ground and kept physically separate from PGND1/PGND2 power return paths. Mixing SGND with power grounds introduces noise into the feedback loop, causing regulation instability or oscillation - proper star grounding at the input capacitor is essential for reliable MIC3172YM operation.
Does the MIC3172YM support external frequency synchronization like the MIC2172?
No - the MIC3172YM has an EN (enable) pin on pin 4, whereas the MIC2172 uses pin 4 for SYNC input. The MIC3172YM's oscillator is fixed at 100 kHz and cannot be synchronized or trimmed externally. If synchronization is required, the MIC2172 or a different controller family (e.g., Microchip's MIC2295) must be selected. The MIC3172YM prioritizes simplicity and enable control over multi-regulator coordination.
MIC3172YM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- 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
MIC3172YM FAQ
1.How can I place an order for MIC3172YM through Aetrix?
Please submit a Request for Quotation (RFQ) for MIC3172YM 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 MIC3172YM reliable?
The price and inventory of MIC3172YM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MIC3172YM is usually 5 days.
3.What payment methods are accepted for MIC3172YM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MIC3172YM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MIC3172YM?
MIC3172YM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MIC3172YM 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 MIC3172YM?
For technical support, including MIC3172YM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MIC3172YM requirements.
6.How does Aetrix verify that MIC3172YM is sourced from the original manufacturer or authorized distributors?
All MIC3172YM 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 MIC3172YM meets industry standards.
7.What is the process for return or replacement of MIC3172YM?
All MIC3172YM units undergo pre-shipment inspection (PSI). If there is an issue with MIC3172YM, 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 MIC3172YM part is unused and in its original packaging.
Return procedure for MIC3172YM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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