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Analog Devices Inc. LT1937ESC6#TRPBF
- Part No.:
- LT1937ESC6#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 6-TSSOP, SC-88, SOT-363
- Datasheet:
-
LT1937ESC6#TRPBF.pdf
- Description:
- IC LED DRV RGLTR PWM SC70-6
- Quantity:
- Payment:
- Shipping:
Inventory:1,880
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Product details
Overview
LT1937ESC6#TRPBF from Analog Devices (formerly Linear Technology) is a constant-current step-up DC/DC converter IC designed specifically to drive white LED strings in portable electronics. It delivers up to 20mA per string, operates from 2.5V to 10V input, switches at 1.2MHz, and features a 95mV feedback reference for high-efficiency current regulation - used in Li-ion–powered devices requiring uniform brightness across 2–4 series LEDs.
For engineers reviewing the LT1937ESC6#TRPBF datasheet, LT1937ESC6#TRPBF pinout, LT1937ESC6#TRPBF application, or LT1937ESC6#TRPBF equivalent, key selection criteria include its SC70-6 package footprint, 36V bipolar switch rating, low 95mV FB voltage, 1.2MHz fixed-frequency current-mode control, and compatibility with 0.22µF ceramic output capacitors and sub-2mm-height inductors.
Technical Context
The LT1937ESC6#TRPBF uses constant-frequency current-mode PWM control with an internal 95mV reference amplifier and ramp-compensated comparator to regulate LED current via external sense resistor. Its 36V-rated bipolar switch enables driving up to four white LEDs (≈12V total VF) from a 3.6V Li-ion source while maintaining >84% typical efficiency.
It integrates shutdown logic with 1.5V enable threshold and 0.4V disable threshold, supports PWM dimming via SHDN pin (1–10kHz), and provides open-circuit protection awareness through duty-cycle limiting - though external zener clamping is required for full SW-pin overvoltage protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 10V - supports single-cell Li-ion (2.7–4.2V) and 3.3V/5V system rails without external LDO pre-regulation. |
| Switching Frequency | 1.2MHz (typ) - enables use of compact 1mm-height inductors and 0.22µF X5R/X7R ceramic output capacitors. |
| Feedback Reference Voltage | 95mV (typ) - minimizes I²R loss in current-sense resistor, improving efficiency vs. higher-VREF alternatives. |
| Switch Current Limit | 320mA (min) - supports ≥15mA LED current into 4× white LEDs (VF ≈ 3V each) with margin for transient loads. |
| Switch Breakdown Voltage | 36V - allows safe operation with up to six white LEDs (≈18V VF) from 5V input or fault-tolerant headroom in 4-LED configurations. |
| Quiescent Supply Current | 2.5mA (typ) - ensures low standby power draw during active LED driving, critical for battery runtime in handhelds. |
| Shutdown Current | 1.0µA (max) - enables deep sleep mode for extended system battery life when LEDs are off. |
Pinout & Package
LT1937ESC6#TRPBF is housed in a 6-lead plastic SC70 package (JEDEC EIAJ SC-70, Analog Devices drawing #05-08-1638), measuring 2.2mm × 1.35mm × 0.95mm (max height), with exposed pad not connected internally. Pin 1 is marked by indentation within index area; recommended solder pad layout follows IPC-7351B Type A.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Switch Node | Connects to inductor and Schottky diode anode; carries high di/dt switching current - minimize trace area to reduce EMI. |
| GND (Pin 2) | Power Ground | Main return path for switch current and IC ground - must connect directly to local ground plane with low-inductance routing. |
| FB (Pin 3) | Current Sense Input | Monitors voltage across external current-setting resistor; 95mV reference sets ILED = 95mV/RFB. |
| SHDN (Pin 4) | Enable/Disable Control | Logic-level input: ≥1.5V enables regulator; ≤0.4V disables it with <1µA quiescent current. |
| GND (Pin 5) | Second Ground Terminal | Dedicated ground connection for improved thermal and noise performance - tie to Pin 2 and ground plane. |
| VIN (Pin 6) | Input Supply | Connects to input capacitor (1µF X5R/X7R); requires local bypassing close to pin to suppress high-frequency ripple. |
Key Features
| Feature | Design Value |
|---|---|
| Inherently matched LED current | Series LED configuration ensures identical current per LED without ballast resistors - eliminates brightness variation across displays or keypad backlights. |
| High conversion efficiency | 84% typical at 15mA/3.6V input driving three white LEDs - extends battery life in space-constrained portable devices. |
| Rugged 36V bipolar switch | Withstands open-circuit transients and enables flexible LED string sizing (2–6 LEDs depending on input rail) without external FETs. |
| Ultra-small external components | Supports 22µH inductors ≤1mm tall and 0.22µF output capacitors - reduces solution footprint below 12mm² total PCB area. |
| Flexible dimming interface | Accepts PWM (1–10kHz), analog DC voltage, filtered PWM, or logic-controlled discrete steps - simplifies integration into diverse UI architectures. |
Applications
| Cellular Phone Keypad Backlight | Digital Camera LCD Backlight |
|---|---|
Use Scenario: Driving 3–4 white LEDs behind membrane keypad in GSM/3G handset with 3.6V Li-ion battery. IC Role / Device Role / Timing Role: Constant-current boost controller regulating LED string current independent of battery voltage sag. Use Value: Maintains consistent brightness across 2.7–4.2V battery range while consuming <2.5mA quiescent current during active backlighting. |
Use Scenario: Powering edge-lit 2.5-inch TFT LCD in compact digital camera using single Li-ion cell. IC Role / Device Role / Timing Role: High-frequency (1.2MHz) step-up converter enabling ultra-low-profile inductor placement near display flex cable. Use Value: Achieves >82% efficiency at 20mA load with 0.22µF output cap - reduces heat generation and board space vs. 500kHz alternatives. |
| PDA Status Indicator Array | GPS Receiver OLED Display Bias |
Use Scenario: Driving dual-color (white + amber) status LED array in enterprise PDA with tight thermal constraints. IC Role / Device Role / Timing Role: Dual-string capable boost driver (via separate RFB) delivering matched current to parallel LED groups. Use Value: Eliminates need for individual current-limiting resistors - reduces BOM count and improves long-term color consistency. |
Use Scenario: Providing regulated bias current to monochrome OLED segment in automotive-grade GPS receiver. IC Role / Device Role / Timing Role: Low-noise, fast-transient current source supporting PWM dimming at 5kHz without audible coil whine. Use Value: Enables flicker-free dimming down to 1% duty cycle while maintaining stable 10mA output despite 3.3V supply ripple. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1932ES5#TRPBF | Same 1.2MHz architecture but rated for up to eight LEDs from 3V; uses TSOT-23-5 (5-pin) package with shared GND/VIN pinout. | Better suited for higher-VF strings (e.g., 5–8 LEDs) and designs where board area favors SOT-23 over SC70. | Select LT1932ES5#TRPBF only if driving ≥5 LEDs or requiring smaller footprint than SC70-6 allows. |
| LTC3200ES6#TRPBF | Inductorless charge pump architecture; fixed 5× or 1× mode; no magnetic components; 2MHz switching. | Lower EMI and smaller solution size, but limited to ≤6 LEDs and lower efficiency (<75%) at >15mA loads. | Choose LTC3200ES6#TRPBF when EMI sensitivity prohibits inductors or when driving ≤4 LEDs at <12mA with strict size limits. |
Compared with LT1937ESC6#TRPBF, LT1932ES5#TRPBF offers higher LED count capability in a smaller package but lacks the second GND pin for improved thermal dissipation, while LTC3200ES6#TRPBF eliminates inductor-related design complexity at the cost of reduced efficiency and output voltage flexibility.
Availability
LT1937ESC6#TRPBF is available at Aetrix Electronics and suitable for cellular phone backlighting, digital camera LCD biasing, and GPS receiver OLED driving requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1937ESC6#TRPBF 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 documentation, and application engineering for legacy Linear parts including the LT1937 family.
The LT1937 belongs to Linear's precision LED driver product line, engineered for space-constrained portable electronics demanding high efficiency, matched current accuracy, and minimal external component count in ultra-thin form factors.
FAQ
What is the maximum number of white LEDs the LT1937ESC6#TRPBF can drive reliably?
The LT1937ESC6#TRPBF can drive up to four white LEDs in series from a 3.2V–4.2V Li-ion source, or up to six white LEDs from a 5V supply, based on its 36V switch rating and typical forward voltage of ~3V per LED. Driving five or six LEDs requires verifying total VF against minimum input voltage and efficiency derating per the datasheet's efficiency curves.
Does the LT1937ESC6#TRPBF require an external zener diode for open-circuit protection?
Yes - the LT1937ESC6#TRPBF lacks internal open-circuit protection. If the LED string opens, the regulator enters high-duty-cycle mode and may exceed its 36V SW pin rating. A zener diode (rated above the max LED string VF but below 36V) must be placed from SW to GND to clamp overvoltage, as specified in the datasheet Figure 5.
Can the LT1937ESC6#TRPBF operate with input voltages below 2.5V?
No - the absolute minimum operating voltage for LT1937ESC6#TRPBF is 2.5V per the Electrical Characteristics table. Operation below this risks failure to start or unstable regulation. For sub-2.5V inputs, consider alternatives like LT1615 or LTC3400 series boost converters.
What is the purpose of the second GND pin (Pin 5) on the LT1937ESC6#TRPBF SC70 package?
Pin 5 is a dedicated ground terminal that improves thermal conduction and reduces ground impedance for high-frequency switch return current. It must be connected to Pin 2 and the local ground plane - separating these paths lowers EMI and enhances stability versus single-GND SOT-23 layouts.
How does the LT1937ESC6#TRPBF achieve constant LED current without sensing voltage across the LEDs?
The LT1937ESC6#TRPBF regulates current by sensing voltage across an external resistor (RFB) placed between the cathode of the lowest LED and GND. Its internal 95mV reference compares to this voltage, adjusting switch duty cycle to maintain ILED = 95mV / RFB - eliminating need for direct LED voltage monitoring.
LT1937ESC6#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 6-TSSOP, SC-88, SOT-363
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 2.5V
- Voltage - Supply (Max):
- 10V
- Voltage - Output:
- 36V
- Current - Output / Channel:
- 320mA (Switch)
- Frequency:
- 1.2MHz
- Dimming:
- Analog, PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SC-70-6
LT1937ESC6#TRPBF FAQ
1.How can I place an order for LT1937ESC6#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1937ESC6#TRPBF 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 LT1937ESC6#TRPBF reliable?
The price and inventory of LT1937ESC6#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1937ESC6#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1937ESC6#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1937ESC6#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1937ESC6#TRPBF?
LT1937ESC6#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1937ESC6#TRPBF 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 LT1937ESC6#TRPBF?
For technical support, including LT1937ESC6#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1937ESC6#TRPBF requirements.
6.How does Aetrix verify that LT1937ESC6#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1937ESC6#TRPBF 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 LT1937ESC6#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1937ESC6#TRPBF?
All LT1937ESC6#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1937ESC6#TRPBF, 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 LT1937ESC6#TRPBF part is unused and in its original packaging.
Return procedure for LT1937ESC6#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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