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Analog Devices Inc. LT1373CN8#PBF
- Part No.:
- LT1373CN8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1373CN8#PBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 1.5A 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,861
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Product details
Overview
LT1373CN8#PBF from Analog Devices (formerly Linear Technology) is a 250kHz constant-frequency current-mode switching regulator IC with integrated 1.5A power switch, designed for boost, buck, flyback, inverting, and Cuk topologies. It delivers up to 1.5A switch current, operates down to 2.7V input, regulates both positive and negative outputs, and achieves >90% efficiency at 5V-to-12V boost conversion.
For engineers reviewing the LT1373CN8#PBF datasheet, LT1373CN8#PBF pinout, LT1373CN8#PBF application, or LT1373CN8#PBF equivalent, key selection considerations include its 1mA quiescent current, 12µA shutdown current, 1.245V feedback reference, –2.45V negative feedback reference, and compatibility with small 15µH inductors in space-constrained DC/DC designs.
Technical Context
The LT1373CN8#PBF implements current-mode control with pulse-by-pulse switch current limiting and adaptive anti-saturation driver logic. Its error amplifier features nonlinear transconductance (250–600 µmho) that increases tenfold above 40mV FB overvoltage to suppress startup overshoot.
Oscillator frequency shifts 5:1 under overload (FB < 0.6V), and the dual-function S/S pin supports logic-level shutdown (threshold 0.6–2.0V) and external synchronization (300–340kHz). The VC pin serves simultaneously as compensation node, soft-start terminal, and current-limit adjust point.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 250 kHz typical; enables use of compact 15µH inductors and reduces EMI filtering burden. |
| Supply Current (IQ) | 1 mA typical; minimizes no-load power loss in battery-powered systems. |
| Shutdown Current | 12 µA typical; extends battery life during system sleep modes. |
| Output Switch Current Limit | 1.5 A minimum; defines maximum deliverable output power in boost/buck configurations. |
| Feedback Reference Voltage | 1.245 V ±15 mV; sets output voltage accuracy via resistor divider on FB pin. |
| Negative Feedback Reference | –2.45 V ±60 mV; enables direct regulation of negative rails without external op-amps. |
| Minimum Input Voltage | 2.7 V; supports single-cell Li-ion and multi-cell alkaline input sources. |
| Error Amplifier Transconductance | 375 µmho typical; determines loop gain and transient response speed in closed-loop regulation. |
Pinout & Package
LT1373CN8#PBF is housed in an 8-lead PDIP (Plastic Dual In-line Package) with 0.3-inch body width and through-hole mounting. Thermal resistance θJA = 100°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (Pin 1) | Compensation / Error Amp Output | External RC network sets loop stability; clamping controls soft-start and current limit. |
| FB (Pin 2) | Positive Output Feedback Input | Connects to resistor divider for +VOUT regulation; bias current ≤150 nA. |
| NFB (Pin 3) | Negative Output Feedback Input | Connects to resistor divider for –VOUT regulation; internal 400kΩ source resistor. |
| S/S (Pin 4) | Shutdown & Sync Input | Logic-low (≤0.6V) enables 12µA shutdown; 300–340kHz AC signal synchronizes switching. |
| VIN (Pin 5) | Input Supply | Accepts 2.7–25V; internal UVLO trips below ~2.5V; bypass with ≥10µF capacitor. |
| GND S (Pin 6) | Ground Sense | Reference ground for error amp and bandgap; must be connected near FB/NFB dividers. |
| GND (Pin 7) | Power Ground | Emitter return for 1.5A switch; requires low-impedance connection to PCB ground plane. |
| VSW (Pin 8) | Switch Node | Collector of internal NPN switch; carries high di/dt; keep trace short to minimize EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 1.5A Power Switch | Eliminates external transistor and driver, reducing BOM count and layout complexity in isolated/non-isolated converters. |
| Dual Polarity Regulation | Single IC regulates both +VOUT (via FB) and –VOUT (via NFB) without auxiliary amplifiers or level shifters. |
| Nonlinear Error Amplifier gm | Transconductance jumps 10× above 40mV FB overvoltage, actively suppressing output overshoot during load transients. |
| Oscillator Frequency Shifting | Reduces switching frequency 5:1 when FB drops below 0.6V, limiting peak switch current during overload or short-circuit events. |
| External Synchronization | Accepts 300–340kHz logic-level sync signal on S/S pin, enabling noise-sensitive systems to avoid critical EMI bands. |
| Low Minimum Input Voltage | 2.7V operation supports single-cell Li-ion (2.7–4.2V) and 3-cell alkaline (3.0–4.5V) battery inputs without pre-regulation. |
Applications
| CCFL Backlight Driver | Laptop Computer Power Supply |
|---|---|
Use Scenario: Driving cold cathode fluorescent lamps in notebook displays requiring regulated high-voltage AC output. IC Role / Device Role / Timing Role: Configured as boost converter with transformer coupling; provides stable 600–1000V AC output at 50–100kHz via resonant tank. Use Value: 250kHz switching enables compact magnetics; 1.5A switch supports up to 10W lamp power; shutdown mode cuts supply current to 12µA during display off. | Use Scenario: Generating 12V rail from 5V main bus in portable computing platforms with strict thermal and board area constraints. IC Role / Device Role / Timing Role: Operated as non-isolated boost regulator; delivers 0.35A at 12V from 5V input using 22µH inductor and MBRS120T3 Schottky diode. Use Value: 1mA IQ extends battery runtime; 0.6 in² total component footprint meets ultra-thin chassis requirements; 90% efficiency at full load reduces thermal load on heat-sensitive components. |
| Multiple Output Flyback Supply | Inverting DC/DC Converter |
Use Scenario: Providing isolated +15V and –15V rails simultaneously for analog front-end circuitry in industrial data acquisition modules. IC Role / Device Role / Timing Role: Used in dual-output flyback topology with shared primary winding; FB and NFB pins independently regulate each output. Use Value: Prevents either rail from overvoltage during unbalanced loading; eliminates need for post-regulators or optocouplers; maintains ±1% output accuracy across –40°C to 125°C. | Use Scenario: Generating –5V from 3–9V battery input for RS-232 interface ICs or op-amp biasing in portable instrumentation. IC Role / Device Role / Timing Role: Configured as inverting converter; NFB pin directly senses negative output; R1/R2 divider sets –5V with 2.49kΩ standard value. Use Value: No external inverting amplifier required; 12µA shutdown current preserves battery life during idle; 2.7V min VIN allows operation down to nearly depleted cells. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3872-1 | Higher 500kHz switching frequency; 3.5A switch; requires external MOSFET gate drive; no integrated NPN switch. | Better suited for high-current (>1A) synchronous buck designs; lacks native negative output regulation capability. | Select LTC3872-1 only when higher efficiency at >1A loads justifies added external FETs and complexity. |
| MAX1759 | Fixed 500kHz frequency; 1.2A switch; 2.5V min VIN; no NFB pin or negative output support; lower IQ (800µA). | Optimized for compact 5V-to-3.3V step-down; cannot replace LT1373CN8#PBF in inverting or dual-rail flyback topologies. | Choose MAX1759 only for simple boost/buck where negative regulation and sub-1mA IQ are not required. |
Compared with LTC3872-1 and MAX1759, the LT1373CN8#PBF uniquely integrates dual-polarity feedback, 1.5A NPN switch, and 1mA IQ in an 8-pin PDIP-making it irreplaceable for space-constrained, battery-powered inverting or dual-output flyback supplies where simplicity and low standby power are mandatory.
Availability
LT1373CN8#PBF is available at Aetrix Electronics and suitable for CCFL backlight drivers, laptop computer power supplies, multiple-output flyback converters, and inverting DC/DC converters requiring stable component supply across industrial temperature ranges.
Supply support for LT1373CN8#PBF 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
Analog Devices acquired Linear Technology in 2017 and maintains its legacy of high-performance analog and power management ICs with rigorous reliability testing and long-term product support.
The LT1373CN8#PBF belongs to Linear's legacy current-mode switching regulator family, engineered specifically for low-quiescent-current, multi-topology DC/DC conversion in portable and space-constrained industrial systems.
FAQ
What is the maximum output current achievable with the LT1373CN8#PBF in a boost configuration?
The LT1373CN8#PBF features a 1.5A internal switch with guaranteed minimum current limit of 1.5A at 50% duty cycle. In a practical 5V-to-12V boost converter, maximum continuous output current is ~0.35A due to thermal limits and efficiency derating. Peak switch current must remain below 1.5A, and inductor saturation must be avoided-designs using 15µH inductors typically achieve 0.3–0.4A output while maintaining >85% efficiency. Always verify thermal performance at worst-case VIN and IOUT.
Can the LT1373CN8#PBF regulate both positive and negative outputs simultaneously?
Yes-the LT1373CN8#PBF supports simultaneous regulation of positive and negative outputs using its dedicated FB and NFB pins. In dual-output flyback applications, the FB pin regulates the positive rail while the NFB pin regulates the negative rail. The IC prevents either output from exceeding its setpoint, even under unbalanced loading. However, FB pin loading must stay below 100µA when NFB is active, requiring careful resistor divider selection per the datasheet's dual polarity equations.
What is the purpose of the VC pin on the LT1373CN8#PBF, and how is it used in design?
The VC pin on the LT1373CN8#PBF serves three critical functions: it is the output of the error amplifier (for loop compensation), the input to the current comparator (for current-mode control), and the node for soft-start and current limit adjustment. A series RC network from VC to GND sets loop stability (pole at 5–30Hz, zero at 2–10kHz). Clamping VC with a capacitor enables soft-start; clamping with a Zener diode limits peak switch current. During normal operation, VC voltage varies between ~1.0V (light load) and ~1.9V (heavy load).
Does the LT1373CN8#PBF require an external diode in boost configuration, and what type is recommended?
Yes-the LT1373CN8#PBF requires an external Schottky diode in boost configuration to conduct output current during switch-off time. The datasheet recommends the MBRS120T3 (20V, 1A) or 1N5818 (30V, 1A) due to their low forward voltage (~0.42V at 1A) and fast recovery. Peak reverse voltage equals the output voltage, so diode VR must exceed VOUT. For 12V outputs, a 20–30V Schottky is sufficient; for higher outputs (e.g., CCFL drivers), select diodes rated ≥600V with appropriate surge capability.
How does the LT1373CN8#PBF handle overload or short-circuit conditions?
The LT1373CN8#PBF employs multiple protection mechanisms during overload: (1) pulse-by-pulse current limiting caps switch current at 1.5A minimum; (2) oscillator frequency shifts 5:1 (to ~50kHz) when FB voltage drops below 0.6V, reducing peak current and power dissipation; (3) thermal shutdown activates if junction temperature exceeds 150°C. Unlike hiccup-mode controllers, it does not auto-restart-recovery requires cycling VIN or toggling the S/S pin. External current limiting via VC clamping is also possible for tighter control.
LT1373CN8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- 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, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 30V
- Voltage - Output (Min/Fixed):
- 1.245V
- Voltage - Output (Max):
- 35V (Switch)
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 250kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LT1373CN8#PBF FAQ
1.How can I place an order for LT1373CN8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1373CN8#PBF 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 LT1373CN8#PBF reliable?
The price and inventory of LT1373CN8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1373CN8#PBF is usually 5 days.
3.What payment methods are accepted for LT1373CN8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1373CN8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1373CN8#PBF?
LT1373CN8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1373CN8#PBF 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 LT1373CN8#PBF?
For technical support, including LT1373CN8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1373CN8#PBF requirements.
6.How does Aetrix verify that LT1373CN8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1373CN8#PBF 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 LT1373CN8#PBF meets industry standards.
7.What is the process for return or replacement of LT1373CN8#PBF?
All LT1373CN8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1373CN8#PBF, 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 LT1373CN8#PBF part is unused and in its original packaging.
Return procedure for LT1373CN8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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