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Analog Devices Inc. LT1317CS8#PBF
- Part No.:
- LT1317CS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1317CS8#PBF.pdf
- Description:
- IC REG BST SEPIC ADJ 710MA 8SO
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT1317CS8#PBF from Analog Devices (formerly Linear Technology) is a micropower, fixed-frequency 600kHz step-up DC/DC converter with integrated 500mA NPN switch and low-battery detector. It operates from 1.5V to 12V input, delivers up to 200mA output, maintains 100µA quiescent current in active mode, and features automatic Burst Mode™ operation for high light-load efficiency. It is widely used in battery-powered portable instrumentation such as glucose meters and GPS receivers.
For engineers reviewing the LT1317CS8#PBF datasheet, LT1317CS8#PBF pinout, LT1317CS8#PBF application, or LT1317CS8#PBF equivalent, key selection criteria include its 1.24V feedback reference, 300mV VCE(SAT) at 500mA, Burst Mode behavior, LBO/LBI low-battery monitoring capability, and SO-8 package compatibility with LT1307/LT1307B designs.
Technical Context
The LT1317CS8#PBF implements current-mode PWM control with a 600kHz oscillator and internal ramp compensation to prevent subharmonic oscillation above 50% duty cycle. Its error amplifier (70–240 µmhos transconductance, 700 V/V gain) drives an external RC compensation network on the VC pin to stabilize the feedback loop across input and load variations.
Burst Mode operation-enabled only in the LT1317 variant-is triggered by the hysteretic comparator A1 when load current drops below ~300µA, reducing average supply current to 100µA while maintaining regulation via periodic switching bursts. The low-battery detector (200mV ±5% reference, active in shutdown) provides open-collector LBO output with 0.25V max sink voltage at 10µA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 600kHz fixed (520–720kHz typical range); enables compact magnetics and low EMI filtering. |
| Input Voltage Range | 1.5V to 12V; supports single-cell alkaline, Li-ion, and multi-cell battery inputs without external regulators. |
| Feedback Reference | 1.24V ±20mV; sets output voltage via external resistor divider (VOUT = 1.24V × (1 + R1/R2)). |
| Quiescent Current | 100µA (active, no switching); drops to 30µA in shutdown-critical for multi-year battery life in medical sensors. |
| Switch VCE(SAT) | 300mV at 500mA; minimizes conduction loss and thermal rise in boost power stage. |
| Burst Mode Threshold | Auto-enters at ~300µA load; sustains regulation with <250mA peak switch current, limiting output ripple even at high VIN. |
| Low-Battery Reference | 200mV ±10mV; remains powered during shutdown, enabling system-level battery monitoring without auxiliary circuitry. |
Pinout & Package
LT1317CS8#PBF is housed in an 8-lead plastic SO (Small Outline) package (S8), 0.150" wide, with standard SO-8 footprint and 120°C/W junction-to-ambient thermal resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (Pin 1) | Compensation node for error amplifier | Connects to external RC network (e.g., 33kΩ + 3.3nF) to set loop bandwidth and phase margin; optional 100pF to ground improves noise immunity. |
| FB (Pin 2) | Feedback input | Monitors output voltage divider; 1.24V reference ensures accurate regulation; bias current ≤60nA minimizes divider error. |
| SHDN (Pin 3) | Shutdown control | Logic-level input: <0.4V disables (only LBI/LBO active); >1.4V enables; draws ≤0.1µA when pulled to VIN. |
| GND (Pin 4) | Power and signal ground | Must connect directly to local ground plane; serves as return for switch, feedback, and reference circuits. |
| SW (Pin 5) | Switch collector node | Drives external inductor/diode; high di/dt requires short, low-inductance trace to minimize EMI and ringing. |
| VIN (Pin 6) | Main power input | Accepts 1.5–12V; must be bypassed with ≥10µF capacitor placed <5mm from pin to prevent instability. |
| LBI (Pin 7) | Low-battery detector input | High-impedance PNP input referenced to 200mV; voltage between 0–700mV; bias current flows out (≤40nA). |
| LBO (Pin 8) | Low-battery detector output | Open-collector NPN output; sinks 10µA max at 0.25V; requires external pull-up (e.g., 1MΩ) to monitor battery status. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Burst Mode™ operation | Maintains regulation at loads as low as 300µA while holding quiescent current to 100µA-enabling decade-long battery life in intermittent-sensing devices. |
| Integrated low-battery detector with 200mV reference | Remains fully functional in shutdown mode, allowing host microcontroller to monitor battery health without waking the converter or adding discrete comparators. |
| Internal 500mA NPN switch with 300mV VCE(SAT) | Eliminates need for external power transistor; reduces BOM count and PCB area while delivering >85% efficiency at 200mA output. |
| Pin-for-pin compatibility with LT1307/LT1307B | Enables drop-in upgrade path from single-cell to wider-input-range boost converters without layout changes or firmware updates. |
| External frequency compensation (VC pin) | Allows optimization of transient response and stability across diverse output capacitors (tantalum, ceramic, polymer) and input conditions. |
Applications
| Glucose Meters | GPS Receivers |
|---|---|
Use Scenario: Portable handheld device measuring blood glucose using electrochemical test strips requiring stable 3.3V rail from 2×AA batteries (1.8–3.2V). IC Role / Device Role / Timing Role: Step-up DC/DC converter generating regulated 3.3V output; Burst Mode extends battery life during standby between measurements. Use Value: 100µA quiescent current and 200mV low-battery threshold enable >2-year shelf life and reliable end-of-battery warning before strip calibration fails. | Use Scenario: Battery-powered GPS module in asset trackers operating from 2.7–4.2V single Li-ion cell, needing clean 3.3V for RF front-end and baseband ICs. IC Role / Device Role / Timing Role: Primary boost regulator supplying 3.3V at up to 200mA; low output ripple in Burst Mode prevents GNSS signal desensitization. Use Value: 300mV VCE(SAT) and 600kHz switching minimize heat and allow use of small 10µH inductors (e.g., Sumida CD43-100), reducing solution size by >30% vs. lower-frequency alternatives. |
| Cordless Telephones | Diagnostic Medical Instrumentation |
Use Scenario: DECT cordless phone base station requiring 5V rail from 5V wall adapter, with undervoltage lockout to prevent brownout resets during line sags. IC Role / Device Role / Timing Role: Boost converter with LBI/LBO monitoring input rail; SHDN pin tied to microcontroller for intelligent power sequencing. Use Value: 200mV reference and 0.25V LBO sink voltage enable precise 4.8V UVLO threshold using simple resistor dividers-eliminating need for dedicated supervisor ICs. | Use Scenario: Portable ultrasound probe with analog front-end demanding low-noise 5V supply from 3.7V Li-ion, plus battery gauge functionality. IC Role / Device Role / Timing Role: Dual-role power converter and battery monitor; LBO output feeds ADC input for real-time state-of-charge estimation. Use Value: Integrated 200mV reference and active-in-shutdown LBI/LBO reduce component count by two precision references and one comparator, improving reliability in Class II medical devices. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1317BCS8#PBF | No Burst Mode; continuous 600kHz operation at all loads; higher light-load quiescent current (~7.5mA). | Eliminates low-frequency output ripple but sacrifices >90% efficiency below 1mA-unsuitable for ultra-low-power sleep modes. | Select when output ripple sensitivity outweighs battery life concerns, e.g., audio codec supplies. |
| LT1307CS8#PBF | Narrower input range (1.0–10V); no low-battery detector; same SO-8 pinout and 600kHz frequency. | Lacks LBI/LBO functionality; cannot support battery monitoring; optimized for single-cell (1.5V) start-up only. | Choose for cost-sensitive, single-cell-only applications where battery health monitoring is handled externally. |
Compared with LT1317BCS8#PBF, the LT1317CS8#PBF trades continuous switching for Burst Mode efficiency below 300µA-extending battery life in intermittent-use medical devices. Against LT1307CS8#PBF, it adds critical low-battery detection and wider input range, enabling robust operation across aging battery profiles.
Availability
LT1317CS8#PBF is available at Aetrix Electronics and suitable for glucose meters, GPS receivers, cordless telephones, and diagnostic medical instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed authentic sourcing.
Supply support for LT1317CS8#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 full product support, datasheet archives, and application engineering for legacy Linear parts including the LT1317 series.
The LT1317CS8#PBF belongs to Linear's micropower DC/DC converter product line, designed specifically for battery-operated portable electronics where ultra-low quiescent current, integrated monitoring, and compact solution size are critical.
FAQ
What is the maximum output current capability of the LT1317CS8#PBF?
The LT1317CS8#PBF supports up to 200mA of continuous output current under typical conditions (e.g., 2V input to 3.3V output). Peak switch current is limited to ~800mA (guaranteed by design), but practical output depends on input voltage, inductor value, and thermal management. At 1.5V input, maximum usable output current decreases due to duty-cycle constraints and VCE(SAT) losses.
Does the LT1317CS8#PBF require an external compensation network?
Yes, the LT1317CS8#PBF requires an external RC network connected to the VC pin (Pin 1) for loop stability. A typical configuration uses 33kΩ in series with 3.3nF to ground. An optional 100pF capacitor from VC to ground improves noise immunity, especially near current limit or with high-ESR output capacitors.
How does the low-battery detector function in shutdown mode for the LT1317CS8#PBF?
The low-battery detector in the LT1317CS8#PBF remains fully operational during shutdown: the 200mV reference and LBI/LBO circuitry stay powered even when SHDN is pulled low. This allows continuous battery voltage monitoring without waking the converter, enabling host microcontrollers to log battery health or trigger alerts while the system is asleep.
Can the LT1317CS8#PBF be used with ceramic output capacitors?
Yes, the LT1317CS8#PBF supports ceramic output capacitors, but compensation must be adjusted. Figure 4 in the datasheet shows a working 2V-to-3.3V design using 10µF ceramic output caps with RC values of 20kΩ and 1500pF. Due to their ultra-low ESR, ceramics can cause instability if original compensation (33kΩ/3.3nF) is retained-always verify loop stability across temperature and load.
What is the difference between LT1317CS8#PBF and LT1317BCS8#PBF?
The LT1317CS8#PBF enters Burst Mode™ at light loads (<300µA) to maintain high efficiency and low quiescent current (100µA), while the LT1317BCS8#PBF operates continuously at 600kHz regardless of load-eliminating low-frequency output ripple but increasing light-load IQ to ~7.5mA. Both share identical pinout, package, and core specifications.
LT1317CS8#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-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Boost, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1.5V
- Voltage - Input (Max):
- 12V
- Voltage - Output (Min/Fixed):
- 1.24V
- Voltage - Output (Max):
- 30V (Switch)
- Current - Output:
- 710mA (Switch)
- Frequency - Switching:
- 620kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1317CS8#PBF FAQ
1.How can I place an order for LT1317CS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1317CS8#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 LT1317CS8#PBF reliable?
The price and inventory of LT1317CS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1317CS8#PBF is usually 5 days.
3.What payment methods are accepted for LT1317CS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1317CS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1317CS8#PBF?
LT1317CS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1317CS8#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 LT1317CS8#PBF?
For technical support, including LT1317CS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1317CS8#PBF requirements.
6.How does Aetrix verify that LT1317CS8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1317CS8#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 LT1317CS8#PBF meets industry standards.
7.What is the process for return or replacement of LT1317CS8#PBF?
All LT1317CS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1317CS8#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 LT1317CS8#PBF part is unused and in its original packaging.
Return procedure for LT1317CS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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