LM2755TMX - Charge Pump LED Driver, I2C, 3-LED, 18-DSBGA | TI
MPN: LM2755TMX/ ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.57 | $25.70 |
| 100 | $2.28 | $228.00 |
| 500 | $2.05 | $1,025.00 |
| 1,000 | $1.82 | $1,820.00 |
LM2755TMX/ Overview
A charge pump is a DC-DC switching converter that uses capacitors instead of inductors to step up or invert a voltage, multiplying the input by a fixed ratio (1x, 1.5x, or 2x). In a portable LED backlight system, the LED driver sits in the power management signal chain between the battery/power-management IC (PMIC) and the LED string. As a "linear regulator > voltage regulator > power management IC > semiconductor" hierarchy member, the LM2755 combines energy conversion with deterministic current regulation, making it ideal for thin display modules that cannot accommodate an inductor.
Key features of the LM2755TMX include 90 mA total LED current across 3 outputs (30 mA per channel), 32-level I2C brightness control, programmable fade-in/fade-out ramps, and 1.2 MHz typical charge-pump switching frequency that allows the use of small 1 uF ceramic flying capacitors. An integrated soft-start limits inrush current, and over-temperature shutdown protects the device during fault conditions. The I2C interface supports 400 kHz Fast Mode and provides access to status registers for fault and identification.
The LM2755 uses a dual-mode charge pump architecture that automatically switches between 1x pass-through and 2x boost to maximize efficiency across the Li-ion discharge curve, achieving roughly 93% peak efficiency at 3.7 V VIN driving white LEDs at 20 mA. Three independent current sinks with 1% current matching ensure uniform display brightness across RGB indicator or keypad applications.
Typical applications include mobile-phone keypad backlighting, RGB status indicators, camera flash (low-current indicator LEDs), portable medical-device displays, and wearable activity-tracker indicator LEDs. The wide 2.7 V to 5.5 V input range also supports USB-powered and 1-cell Li-ion designs directly without a pre-regulator.
When designing with this device, observe the 18-ball DSBGA layout guidelines strictly - the device requires a four-layer PCB with a continuous ground plane and vias under the thermal pad to dissipate up to 0.5 W. The I2C address is fixed (0xC8 7-bit), so multiple LM2755 instances on the same bus are not supported; for multi-channel designs, select the LM2756/LM2757 family instead.
This page synthesizes distributor pricing, verified drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for LM2755TMX/ — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LM2755TMX/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
LM2755TM/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
LM2755TM
✅ Drop-In📋 Reference alternative (not in catalog)
LM2755TMX/ Maximum Ratings & Electrical Characteristics
| Topology | Switched Capacitor (Charge Pump) |
| Input Voltage Range | 2.7 V to 5.5 V |
| Number of Outputs | 3 |
| Maximum Total LED Current | 90 mA (30 mA per channel) |
| Switching Frequency | 1.2 MHz typical |
| Charge Pump Modes | 1x / 2x (automatic) |
| Interface | I2C-compatible (Fast Mode 400 kHz) |
| Current Matching | 1% (channel-to-channel) |
| Operating Temperature | -30 C to +85 C |
| MSL Level | 1 |
| RoHS Status | Compliant |
| Soft-Start | Integrated |
| Thermal Shutdown | Yes |
LM2755TMX/ Pin Configuration
| Pin A1 | LED1 — Current sink output for LED 1 |
| Pin A2 | LED2 — Current sink output for LED 2 |
| Pin A3 | LED3 — Current sink output for LED 3 |
| Pin B1 | C1+ — Flying capacitor 1, positive terminal |
| Pin B2 | C1- — Flying capacitor 1, negative terminal |
| Pin B3 | GND — Ground reference |
| Pin C1 | C2+ — Flying capacitor 2, positive terminal |
| Pin C2 | C2- — Flying capacitor 2, negative terminal |
| Pin C3 | VOUT — Charge pump output (LED anode supply) |
| Pin D1 | VIN — Input supply voltage |
| Pin D2 | GND — Ground reference |
| Pin D3 | SDA — I2C data |
| Pin E1 | SCL — I2C clock |
| Pin E2 | AD — I2C address select |
| Pin E3 | INT — Interrupt output (open-drain) |
| Pin F1 | NC — Not connected (per datasheet) |
| Pin F2 | NC — Not connected (per datasheet) |
| Pin F3 | GND — Ground reference |
Typical Applications
LM2755TMX/ is suitable for 6 applications: Mobile Phone Keypad Backlight, RGB Status Indicator LED, Wearable Fitness Tracker Indicator, Portable Medical Device Display, USB-Powered LED Indicator Strip, IoT Sensor Node Status LED.
Mobile Phone Keypad Backlight
The LM2755TMX is a strong fit for mobile-phone keypad backlighting because it integrates 3 matched current sinks, an I2C-programmable brightness ramp, and a small 1.2 MHz charge pump that uses 1 uF ceramic flying capacitors. Three current sinks at 30 mA each directly drive the three keypad zones (e.g., function, navigation, numeric) with 1% matching for uniform brightness. Unlike a discrete boost-plus-resistor solution, the LM2755TMX occupies under 4 mm^2 of PCB area, fits in the 18-DSBGA, and provides fade-in/fade-out transitions for premium UI feel. Efficiency is typically 90-93% across the Li-ion discharge curve due to automatic 1x/2x mode switching, minimizing battery drain during active backlight use.
Recommended
RGB Status Indicator LED
The LM2755TMX drives RGB status indicators in consumer electronics and IoT devices by providing three independent current sinks, each programmable to a different current level via I2C. This allows red, green, and blue LEDs to be mixed for color-tunable status feedback (e.g., breathing white, blinking blue for connectivity) without external PWM logic. The 30 mA per channel rating supports high-brightness SMD RGB LEDs for visible daylight indication. The 1.2 MHz switching frequency is well above the audio band, preventing audible noise during operation. The 18-DSBGA package allows the driver to sit directly beneath the indicator LED cluster, minimizing trace length and EMI.
Recommended
Wearable Fitness Tracker Indicator
The LM2755TMX fits wearable fitness-tracker indicator applications because its 18-DSBGA package measures roughly 1.7 mm x 1.4 mm, fitting into the tightest of wrist-worn enclosures, while delivering 90 mA total current for notification LEDs. The 2.7-5.5 V input range allows direct connection to the 3.7 V Li-ion cell without pre-regulation, reducing the BOM by one LDO. Programmable fade-in/fade-out ramp registers enable the smooth notification flashes expected in modern wearables. Integrated thermal shutdown protects the device during sustained high-current operation in an enclosed, low-thermal-mass enclosure.
Recommended
Portable Medical Device Display
The LM2755TMX supports portable medical-device display backlights (e.g., glucose meter, pulse oximeter) by providing stable, flicker-free constant current that meets medical display readability requirements. The 1% channel-to-channel current matching ensures uniform backlight brightness across the LCD, critical for accurate reading in low-light clinical environments. The I2C interface allows the host MCU to adjust brightness in response to ambient light sensor input, reducing eye strain. The integrated soft-start eliminates inrush current that could cause voltage dips on the shared battery rail in safety-critical medical devices.
Recommended
USB-Powered LED Indicator Strip
The LM2755TMX operates directly from the 5 V USB rail without a pre-regulator thanks to its 2.7-5.5 V input range, simplifying USB-powered LED-indicator designs in docking stations, hubs, and computer peripherals. The 1x pass-through mode at 5 V VIN achieves >95% efficiency since the charge pump is bypassed. The I2C interface allows host control (e.g., for activity-status indication tied to USB enumeration events). The 18-DSBGA package enables integration in slim USB-C dongle form factors. The part's small 1 uF flying capacitors avoid the bulky inductors that would be needed in a boost-based design.
Recommended
IoT Sensor Node Status LED
The LM2755TMX fits IoT sensor node status-LED applications (e.g., smart-home, environmental sensors) where the design must minimize standby current while still providing user feedback. The 1x pass-through mode in the LM2755TMX draws only the LED current itself when VIN is above the LED forward voltage, avoiding the 2-3 mA quiescent current of competing boost converters. The I2C interface is shared with the host MCU's main I2C bus, adding no extra GPIO. The 18-DSBGA's small footprint and 1.2 MHz switching frequency (above the AM broadcast band) make it ideal for FCC/CE-compliant wireless sensor nodes where the LED driver must not inject noise into the RF chain.
Recommended
Recommended Products Summary
Engineering reference data for LM2755TMX/ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LM2755TMX/NOPB | LM2755TM/NOPB | LM2755TM |
|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 18-DSBGA (Micro SMD) | 18-DSBGA - same | 18-DSBGA - same | 18-DSBGA - same |
| Topology | Charge Pump (1x/2x) | Charge Pump (1x/2x) | Charge Pump (1x/2x) | Charge Pump (1x/2x) |
| Input Voltage Range | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V |
| Number of Outputs | 3 | 3 | 3 | 3 |
| Total LED Current | 90 mA | 90 mA | 90 mA | 90 mA |
| Switching Frequency | 1.2 MHz | 1.2 MHz | 1.2 MHz | 1.2 MHz |
| Interface | I2C | I2C | I2C | I2C |
| RoHS / Pb-Free | Varies (TMX is non-Pb-free, TMX/NOPB is Pb-free) | Pb-free (NOPB) | Pb-free (NOPB) | Non-Pb-free (legacy) |
| Packaging Form | Tape & Reel (TMX) | Tape & Reel | Tray | Tray |
Key Differentiators
- Pb-free / RoHS compliant version available in same footprint (vs LM2755TMX (non-Pb-free))
- Tray packaging option for low-volume prototyping (vs LM2755TMX (Tape & Reel only))
- Industry-standard 1.2 MHz charge pump avoids AM-band interference (vs Generic 1x/2x charge-pump LED drivers)
Design Notes
The 18-DSBGA package requires a four-layer PCB with a continuous ground plane and an array of thermal vias directly under the die to dissipate up to 0.5 W during sustained 90 mA operation. Place the 1 uF flying capacitors C1 and C2 within 2 mm of the C1+/C1-/C2+/C2- balls, using short, wide traces to minimize parasitic inductance. The exposed die paddle must be soldered to a flooded ground pad for electrical and thermal performance. Decoupling the VIN pin with a 1 uF X5R/X7R ceramic capacitor placed within 1 mm is critical for charge-pump stability.
In 1x pass-through mode at 5 V VIN driving 3 LEDs at 30 mA with a 3.0 V forward voltage, the LM2755TMX dissipates approximately (5V - 3V) x 90mA = 0.18 W. In 2x boost mode at 2.7 V VIN, dissipation is approximately (2 x 2.7V - 3V) x 90mA = 0.21 W. With the 18-DSBGA's theta_JA of approximately 90 C/W on a 4-layer JEDEC test board, junction temperature rise is around 19 C above ambient - well within the 85 C operating limit at room temperature. Avoid continuous operation in 2x mode above 60 C ambient.
The I2C address is fixed (7-bit 0x18 per TI datasheet), so multiple LM2755TMX instances on the same I2C bus will conflict - for multi-channel or multi-zone designs, select the LM2756 or LM2757 family which supports programmable addresses. The INT pin is open-drain and requires a pull-up to the I/O supply voltage (typically 1.8 V or 3.3 V), not to VIN. Do not exceed the absolute maximum VIN of 6.0 V; even brief transients above 5.5 V can damage the charge-pump capacitors. LED outputs (LED1/2/3) are current sinks, not sources - the LED anode must be tied to VOUT and the cathode to the LEDx pin.
Compliance Information
The /NOPB suffix denotes Pb-free / RoHS compliance per TI's standard ordering convention. The non-/NOPB version is the legacy part with lead-containing terminations. AEC-Q100 qualification status: the LM2755TMX is not AEC-Q100 qualified and is therefore not recommended for automotive applications requiring Grade 1 (-40C to +125C) operation.
