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Analog Devices Inc. LTC1840CGN#TRPBF
- Part No.:
- LTC1840CGN#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Motor Drivers, Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC1840CGN#TRPBF.pdf
- Description:
- IC MOTOR DRVR 2.7V-5.75V 16SSOP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LTC1840CGN#TRPBF from Analog Devices (formerly Linear Technology) is a dual fan controller IC with two 8-bit current-output DACs, two programmable tachometer interfaces, and four GPIO pins. It operates from a single 2.7V–5.75V supply, delivers 95–105µA full-scale DAC sink current, supports I²C/SMBus communication up to 100kHz, and is rated for 0°C to 70°C operation in a 16-pin SSOP package. It enables closed-loop fan speed control in server cooling systems.
For engineers reviewing the LTC1840CGN#TRPBF datasheet, LTC1840CGN#TRPBF pinout, LTC1840CGN#TRPBF application, or LTC1840CGN#TRPBF equivalent, key selection criteria include guaranteed monotonic 8-bit DAC performance, tachometer counter overflow fault detection, BLAST-triggered full-scale DAC override, and nine configurable I²C addresses via A0/A1 three-state inputs.
Technical Context
The LTC1840CGN#TRPBF integrates a 50kHz internal oscillator divided by 2/4/8/16 to generate tachometer clock frequencies (3.125–25kHz), and uses current-sink DAC outputs to interface with external switching regulators (e.g., LTC1771) for precise fan voltage control. Its serial interface includes a watchdog timer that triggers DAC blast and fault if no I²C access occurs within ~90 seconds.
Each tachometer input (TACHA/TACHB) counts rising edges and latches 255 on overflow-enabling immediate detection of stalled fans-while GPIO pins support configurable open-drain pull-downs (10mA sink), blink mode, and logic-change fault generation. The FAULT pin asserts low on any detected condition including UVLO, tach overflow, GPIO state change, or BLAST event.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| DAC resolution | 8-bit, monotonic over full range-ensures predictable fan speed increments without step reversals. |
| DAC full-scale current | 95–105 µA at VDACOUT = 1.1V-sets regulator feedback voltage range for 5–12V fan supply control. |
| Tachometer frequency options | 3.125 / 6.25 / 12.5 / 25 kHz-selectable via DIV1/DIV0 bits to match fan pulse rates and avoid aliasing. |
| I²C bus frequency | DC to 100 kHz-supports standard-mode I²C and SMBus timing without external clock stretching. |
| Supply voltage range | 2.7V to 5.75V-compatible with 3.3V and 5V system rails; UVLO threshold 2.1–2.69V with 20–160mV hysteresis. |
| Operating temperature | 0°C to 70°C (Commercial grade)-validated for desktop computers, power supplies, and server ambient environments. |
| Package | 16-lead SSOP (GN), 0.150" width-surface-mount compatible with standard reflow profiles; θJA = 110°C/W. |
Pinout & Package
Package: 16-lead plastic SSOP (GN), narrow body (0.150"), JEDEC MS-013AC compliant. Pin pitch: 0.025", body width: 3.81–3.99 mm, max mold flash: 0.152 mm per side.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SCL | Serial clock input | CMOS input with 1V threshold; requires external pull-up; clocks data on rising edge for I²C/SMBus communication. |
| SDA | Serial bidirectional data | Open-drain output with 1V threshold; shared bus line; master and device alternate control during read/write cycles. |
| A1, A0 | Three-state address inputs | Each accepts VCC (H), GND (L), or NC to configure one of nine unique I²C slave addresses (111xxxxx format). |
| FAULT | Open-drain fault indicator | Pulls low on UVLO, tach overflow, GPIO fault, or BLAST event; requires external pull-up resistor (e.g., 10kΩ). |
| IDACOUTA/B | Current-sink DAC outputs | High-impedance outputs sinking 0–100 µA; compliance voltage ≥1.1V; used to set feedback node voltage of external DC/DC controllers. |
| TACHA/TACHB | Digital tachometer inputs | CMOS inputs counting rising edges; overflow latches 255; fault enable configurable per channel via STATUS register. |
| GPIO1–GPIO4 | Programmable I/O | Configurable as CMOS inputs or open-drain outputs (10mA sink); support blink mode and logic-change fault triggering. |
| BLAST | Blast/timer control input | 1V threshold; high at POR forces DACs to full scale and enables serial watchdog timer (~90s timeout). |
Key Features
| Feature | Design Value |
|---|---|
| Two 8-bit monotonic current DACs | Guaranteed DNL ±0.9 LSB ensures smooth, non-reversing fan speed transitions across full 256-step range. |
| Programmable tachometer counters | Overflow latching (255) and fault enable per channel allow immediate stalled-fan detection without polling delay. |
| Four configurable GPIOs | Support LED drive (with series resistor), digital input sensing, and software-cleared logic-change faults. |
| Serial interface watchdog timer | Auto-triggers DAC blast and FAULT assertion after ~90s of I²C inactivity-prevents silent control lockup. |
| Nine I²C address options | Three-state A0/A1 pins eliminate address conflicts in multi-controller systems (e.g., dual-CPU servers). |
Applications
| Server Cooling Control | Desktop PC Thermal Management |
|---|---|
|
Use Scenario: Dual-fan thermal regulation in 1U/2U rack servers with independent CPU/GPU heat sinks. IC Role / Device Role / Timing Role: Fan controller providing closed-loop velocity control via DAC-regulator-tach feedback paths; BLAST pin enables emergency full-speed override during thermal alerts. Use Value: Prevents thermal throttling by maintaining target RPM under variable load; fault latching simplifies BMC diagnostics. |
Use Scenario: Intelligent fan speed adjustment in consumer desktop motherboards based on CPU and chipset temperature sensors. IC Role / Device Role / Timing Role: Dual-channel fan manager interfacing with BIOS via SMBus; GPIOs drive status LEDs and monitor front-panel switches. Use Value: Reduces acoustic noise during idle while ensuring rapid response to sudden thermal events via programmable tach thresholds. |
| Industrial Power Supply Monitoring | Network Equipment Fan Control |
|
Use Scenario: Active cooling supervision in telecom rectifiers and AC/DC PSUs where fan failure must trigger shutdown. IC Role / Device Role / Timing Role: Fault-aware controller monitoring tach signals and asserting FAULT pin to upstream supervisor IC upon rotor stall or open-circuit fan. Use Value: Enables fail-safe operation: FAULT signal can disable main power stage or initiate graceful shutdown before overheating. |
Use Scenario: Multi-fan airflow management in 19-inch rack-mounted switches/routers with redundant cooling zones. IC Role / Device Role / Timing Role: Centralized tach aggregation and DAC-based voltage control for up to four fans via wired-OR tach inputs and external FET drivers. Use Value: Simplifies BOM with single IC handling dual independent loops; nine I²C addresses support stacking multiple units on same bus. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual fan controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1695CMS8#TRPBF | Single-channel fan controller in 8-pin MSOP; integrates 0.75Ω PMOS linear regulator (180mA); no GPIOs or BLAST function. | Targeted at low-power, single-fan applications (e.g., small form-factor PCs); lacks tach overflow fault latching and DAC programmability. | Select when space-constrained layout and integrated linear regulation outweigh need for dual control or fault robustness. |
| ADM1032ARMZ-REEL | Temp sensor + single tach interface + PWM fan output; no current DACs; SMBus-only; 10-bit temp resolution. | Focused on temperature-triggered PWM control-not closed-loop velocity control; requires external PWM-to-voltage conversion for analog fans. | Choose when primary requirement is precision thermal monitoring with basic fan speed modulation, not DAC-based regulator control. |
Compared with LTC1840CGN#TRPBF, LTC1695CMS8#TRPBF offers smaller footprint and integrated regulation but sacrifices dual-channel capability and fault intelligence, while ADM1032ARMZ-REEL provides superior temperature accuracy but cannot implement current-sink DAC feedback loops essential for stable switching-regulator fan control.
Availability
LTC1840CGN#TRPBF is available at Aetrix Electronics and suitable for server cooling systems, desktop thermal management, and industrial power supply monitoring requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC1840CGN#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 its precision analog and power management product lines. Linear pioneered high-performance analog ICs for demanding industrial and computing applications.
The LTC1840CGN#TRPBF belongs to Linear's dedicated thermal management IC family, designed specifically for reliable, fault-aware fan control in high-availability computing infrastructure where silent operation and fail-safe response are critical.
FAQ
What is the function of the BLAST pin on the LTC1840CGN#TRPBF?
The BLAST pin on the LTC1840CGN#TRPBF serves two roles: it forces both current DAC outputs to full scale (100 µA) upon power-up or high-to-low transition, and it enables the serial interface watchdog timer. When asserted, BLAST immediately overrides programmed DAC values to maximize fan speed-critical for emergency thermal response. The LTC1840CGN#TRPBF also uses BLAST to gate timer activation, preventing unintended blasts if the pin is held low during normal operation.
How does the LTC1840CGN#TRPBF detect a stalled fan?
The LTC1840CGN#TRPBF detects a stalled fan by monitoring tachometer input counters (TACHA/TACHB). Each counter increments on rising edges and latches 255 on overflow-immediately indicating zero rotation. If the corresponding FLTEN bit is enabled in the STATUS register, this overflow sets a latched fault bit in the FAULT register and pulls the FAULT pin low. The LTC1840CGN#TRPBF retains the 255 value even after the next edge, enabling reliable stalled-rotor identification without waiting for subsequent pulses.
Can the LTC1840CGN#TRPBF control fans powered by different supply voltages?
Yes-the LTC1840CGN#TRPBF controls fan speed indirectly via current-sink DAC outputs driving the feedback node of external switching regulators (e.g., LTC1771), which can be configured for different output voltages (e.g., 5V and 12V). The DAC compliance voltage (≥1.1V) and full-scale current (95–105 µA) allow independent tuning of each regulator's feedback divider. The LTC1840CGN#TRPBF itself operates from a single 2.7–5.75V supply and does not directly power fans.
What are the default states of GPIO pins on power-up for the LTC1840CGN#TRPBF?
On power-up, all four GPIO pins (GPIO1–GPIO4) of the LTC1840CGN#TRPBF default to nonfaulting CMOS digital inputs with internal pull-downs disabled. Their corresponding GPIO register bits power up high (turning off the N-channel MOSFET pull-down), and GPIO FLTEN bits power up low (disabling fault generation on logic change). This safe default prevents unintended output drive or false fault assertions until firmware explicitly configures them via the I²C interface.
Does the LTC1840CGN#TRPBF support SMBus Alert Response Address (ARA)?
No-the LTC1840CGN#TRPBF does not support SMBus Alert Response Address (ARA). It implements a standard 2-wire I²C/SMBus interface with fixed slave addressing via A0/A1 pins (nine possible addresses), but lacks the ARA hardware required to respond to the general call address 0x0C. Fault conditions are signaled solely through the open-drain FAULT pin; host systems must poll the FAULT register or monitor the pin level externally to identify root cause.
LTC1840CGN#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Motor Type - Stepper:
- -
- Motor Type - AC, DC:
- Brushed DC
- Function:
- Controller - Speed
- Output Configuration:
- Pre-Driver - High Side (2)
- Interface:
- I2C, SMBus
- Technology:
- PMOS
- Step Resolution:
- -
- Applications:
- Fan Controller
- Current - Output:
- -
- Voltage - Supply:
- 2.7V ~ 5.75V
- Voltage - Load:
- -
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LTC1840CGN#TRPBF FAQ
1.How can I place an order for LTC1840CGN#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1840CGN#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 LTC1840CGN#TRPBF reliable?
The price and inventory of LTC1840CGN#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1840CGN#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1840CGN#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1840CGN#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1840CGN#TRPBF?
LTC1840CGN#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1840CGN#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 LTC1840CGN#TRPBF?
For technical support, including LTC1840CGN#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1840CGN#TRPBF requirements.
6.How does Aetrix verify that LTC1840CGN#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1840CGN#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 LTC1840CGN#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1840CGN#TRPBF?
All LTC1840CGN#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1840CGN#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 LTC1840CGN#TRPBF part is unused and in its original packaging.
Return procedure for LTC1840CGN#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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