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Analog Devices Inc. LTC1174IS8#PBF
- Part No.:
- LTC1174IS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1174IS8#PBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:345
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Product details
Overview
LTC1174IS8#PBF from Analog Devices (formerly Linear Technology) is a high-efficiency, current-mode step-down and inverting DC/DC converter with internal 0.9Ω P-channel MOSFET switch, pin-selectable 340mA/600mA current limit, and 130µA standby current. It operates from 4V to 18.5V input, delivers regulated 5V output (fixed version), and supports low-battery detection for portable battery-powered equipment.
For engineers reviewing the LTC1174IS8#PBF datasheet, LTC1174IS8#PBF pinout, LTC1174IS8#PBF application, or LTC1174IS8#PBF equivalent, key selection criteria include its constant off-time architecture, micropower shutdown (1µA), ±5V inverting capability, and compatibility with small surface-mount inductors (e.g., CTX50-4) in space-constrained designs.
Technical Context
The LTC1174IS8#PBF implements a constant off-time (COT) control architecture with wafer-sort trimmed tOFF ≈ 4µs, resulting in VIN-dependent switching frequency (e.g., ~111kHz at VIN=9V, VOUT=5V). Its current-mode loop integrates burst-mode operation at light loads to reduce quiescent current from 600µA active to 130µA sleep mode.
Regulation uses a 1.25V internal reference with feedback via VFB (Pin 1); for fixed-output variants like LTC1174-5, internal resistive dividers set VOUT = 4.75–5.25V. Low-battery detection compares VIN-derived voltage at LBIN (Pin 3) against 1.25V reference, sinking up to 1.2mA at LBOUT (Pin 2) when trip occurs at 1.25–1.4V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 18.5V - supports wide battery chemistries including 4×NiCd (4.8V) and 12V lead-acid systems. |
| Output Voltage | 5.00V (±5%) - fixed regulation for 5V logic rails without external feedback resistors. |
| Peak Efficiency | 94% - achieved at ~300mA load with VIN=9V, L=100µH, enabling thermally constrained portable designs. |
| Quiescent Current | 130µA - enables >1-year battery life in always-on monitoring applications with intermittent wake-up. |
| Shutdown Current | 1µA - reduces system standby power to negligible levels during deep sleep modes. |
| Current Limit | 340mA or 600mA - selected by IPGM pin (0V or VIN), allowing optimization of inductor size vs. peak current capability. |
| Switch RDS(on) | 0.9Ω (typ) - limits conduction loss at 9V supply, supporting >85% efficiency even at 100mA loads. |
Pinout & Package
Package: 8-lead plastic SO (S8), RoHS-compliant, surface-mount, 150°C/W junction-to-ambient thermal resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (VFB*) | Feedback input / regulated output | Pin 1 connects to internal 1.25V comparator for adjustable versions; on LTC1174-5, it's internally tied to fixed 5V divider - no external resistor needed. |
| LBOUT | Open-drain low-battery indicator output | Sinks up to 1.2mA when LBIN voltage drops below 1.25V; requires external pull-up for LED or MCU interrupt signaling. |
| LBIN | Inverting input of low-battery comparator | Accepts resistor-divider from VIN to set trip point (e.g., 5.5V with 162k/4.7k); draws only 0.5µA bias current. |
| GND | Power and signal reference ground | Must be low-impedance star point for SW, CIN, and COUT return paths to minimize noise and EMI. |
| SHUTDOWN | Active-low enable control | Pull to GND for 1µA shutdown; float or tie to VIN for normal operation; VIH ≥1.2V, VIL ≤0.75V. |
| IPGM | Current limit select | 0V → 340mA limit; VIN → 600mA limit; high-impedance input requiring solid logic level to avoid erratic current limiting. |
| VIN | Main input supply | Accepts 4–18.5V; requires local 0.1µF ceramic + bulk capacitor (e.g., 47µF) placed within 5mm of Pin 6 and Pin 4. |
| SW | Drain of internal P-MOSFET | Connects directly to cathode of Schottky catch diode (e.g., MBRS140T3); high dv/dt node requiring tight layout to minimize EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® operation | Reduces quiescent current to 130µA at light loads while maintaining tight output regulation via hysteretic voltage control. |
| Pin-selectable current limit | Enables single BOM to support both low-power (340mA) and higher-current (600mA) variants without layout change. |
| Internal 0.9Ω P-channel switch | Eliminates need for external high-side FET, reducing component count to just four: inductor, diode, input cap, output cap. |
| Low-battery detector with hysteresis | 7.5–30mV hysteresis prevents chatter near trip point; LBOUT sink current allows direct LED drive or microcontroller GPIO interface. |
| Constant off-time architecture | Provides inherent line regulation and stable operation across wide VIN range without compensation network. |
Applications
| Portable Medical Sensors | Industrial Data Loggers |
|---|---|
Use Scenario: Wearable ECG sensor powered by two AA alkaline cells (2.4–3.2V), requiring clean 3.3V rail for ADC and BLE radio. IC Role / Device Role / Timing Role: Step-down converter generating stable 3.3V from unregulated battery source; LBIN/LBOUT monitors cell depletion to trigger low-power alert before shutdown. Use Value: 94% peak efficiency extends runtime by >20% vs. linear regulator; 130µA sleep current enables multi-week standby without recharge. | Use Scenario: Remote environmental monitor using Li-ion battery (3.0–4.2V) and solar trickle charge, logging temperature/humidity every 5 minutes. IC Role / Device Role / Timing Role: Inverting converter generating –5V for op-amp biasing and sensor excitation; SHUTDOWN pin synchronized to MCU sleep cycle. Use Value: Micropower shutdown (1µA) eliminates parasitic drain during 4.95-minute sleep intervals, maximizing energy harvesting yield. |
| Handheld Test Equipment | Memory Backup Power |
Use Scenario: Battery-operated multimeter with dual-rail analog front-end (±5V) and 3.3V digital core, powered by 9V alkaline. IC Role / Device Role / Timing Role: Primary 9V→5V step-down regulator; secondary LTC1174-5 configured as inverter for –5V rail using shared inductor topology. Use Value: Only four external components per rail reduces PCB area by 35% vs. discrete buck-boost solutions; 18.5V max VIN accommodates 9V battery surge. | Use Scenario: Industrial PLC retaining SRAM and real-time clock during main power failure, backed by supercapacitor charged from 5V system rail. IC Role / Device Role / Timing Role: Inverting converter generating –5V from 5V backup rail to bias EEPROM write-protection circuitry during brownout. Use Value: Internal current limit prevents supercap over-discharge; short-circuit protection ensures safe fault recovery when main power restores. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1931IS5#TRMPBF | Fixed 5V output, 1.25MHz constant-frequency PWM, 600mA switch, 2.7–10V input. | Higher switching frequency enables smaller inductors but increases EMI sensitivity; lacks low-battery detection. | Choose for compact layouts where EMI filtering is feasible and battery monitoring is handled externally. |
| TPS61040DRVR | Boost-only topology, 28V output capability, 500kHz fixed frequency, 0.5A switch, 1.8–6V input. | Cannot perform step-down or inverting functions; optimized for low-input-voltage boost (e.g., single-cell Li-ion to 3.3V). | Use only when input voltage is always below required output (e.g., 3.3V system rail boosting to 5V for USB peripheral). |
Compared with LT1931IS5#TRMPBF and TPS61040DRVR, the LTC1174IS8#PBF uniquely combines step-down, inverting, and battery-monitoring functions in one IC with ultra-low quiescent current-making it irreplaceable in dual-rail portable instruments where board space and battery life are co-constrained.
Availability
LTC1174IS8#PBF is available at Aetrix Electronics and suitable for portable medical sensors, industrial data loggers, handheld test equipment, and memory backup power systems requiring stable component supply across extended production lifecycles.
Supply support for LTC1174IS8#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC1174IS8#PBF belongs to Linear's legacy DC/DC converter product line, designed specifically for battery-powered portable instrumentation requiring high efficiency, micropower operation, and integrated system monitoring features.
FAQ
What is the operating temperature range for the LTC1174IS8#PBF?
The LTC1174IS8#PBF is rated for –40°C to +85°C ambient operation (I-grade), with a maximum junction temperature of 125°C. Its thermal resistance θJA is 150°C/W in the 8-lead SO package, requiring minimal heatsinking in typical 350mA-load applications with moderate airflow.
Does the LTC1174IS8#PBF support adjustable output voltages?
No - the LTC1174IS8#PBF is the base part number for the adjustable version, but the specific variant LTC1174IS8#PBF corresponds to the I-grade 8-pin SO package with no suffix, meaning it requires external feedback resistors on VFB (Pin 1) to set output voltage. Fixed 3.3V or 5V versions use suffixes like -3.3 or -5 (e.g., LTC1174IS8-5#PBF).
How does the low-battery detector function on the LTC1174IS8#PBF?
The LTC1174IS8#PBF's low-battery detector compares a resistor-divided VIN signal at LBIN (Pin 3) against an internal 1.25V reference. When the divided voltage falls below 1.25V (trip range 1.25–1.4V), LBOUT (Pin 2) sinks up to 1.2mA. The detector is disabled during shutdown, and hysteresis (7.5–30mV) prevents oscillation near the threshold.
Can the LTC1174IS8#PBF be used in inverting configurations?
Yes - the LTC1174IS8#PBF supports inverting topologies (e.g., 5V-to–5V) by grounding the output and taking VOUT from the GND pin. This configuration requires careful attention to absolute maximum ratings: SW pin voltage must not exceed VIN by more than 0.3V, necessitating a clamp diode in some cases per Figure 6 of the datasheet.
What is the recommended inductor for the LTC1174IS8#PBF in a 5V output application?
For a 5V output at 350mA with VIN=9V, a 50µH surface-mount inductor such as Coiltronics CTX50-4 is recommended. This value balances ripple current (≈500mA peak-to-peak), core loss, and physical size. Higher inductance (e.g., 100µH) reduces ripple but increases copper loss; lower values require tighter ESR control on output capacitors.
LTC1174IS8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- 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, Buck-Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 18.5V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 13V
- Current - Output:
- 340mA, 600mA
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1174IS8#PBF FAQ
1.How can I place an order for LTC1174IS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1174IS8#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 LTC1174IS8#PBF reliable?
The price and inventory of LTC1174IS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1174IS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC1174IS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1174IS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1174IS8#PBF?
LTC1174IS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1174IS8#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 LTC1174IS8#PBF?
For technical support, including LTC1174IS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1174IS8#PBF requirements.
6.How does Aetrix verify that LTC1174IS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1174IS8#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 LTC1174IS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC1174IS8#PBF?
All LTC1174IS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1174IS8#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 LTC1174IS8#PBF part is unused and in its original packaging.
Return procedure for LTC1174IS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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