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Texas Instruments LM2787BPX
- Part No.:
- LM2787BPX
- Manufacturer:
- Texas Instruments
- Package:
- 8-VFBGA
- Datasheet:
-
LM2787BPX.pdf
- Description:
- IC REG CHARG PUMP ADJ 10MA 8USMD
- Quantity:
- Payment:
- Shipping:
Inventory:3,590
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Product details
Overview
LM2787BPX from Texas Instruments is a regulated switched-capacitor voltage inverter IC that inverts and regulates input supply voltage to deliver low-noise, adjustable negative output (−1.5V to −5.2V) from +2.7V to +5.5V input. It delivers up to 10mA output current with 91% typical charge-pump efficiency at 10mA, 260kHz switching frequency, and 1mV output ripple at 2.5mA load - ideal for cellular phone power amplifier biasing.
For engineers reviewing the LM2787BPX datasheet, LM2787BPX pinout, LM2787BPX application, or LM2787BPX equivalent, key selection criteria include its DSBGA-8 package footprint, active-low shutdown (0.05µA quiescent), feedback-based output adjustability, and PSRR-enhanced linear regulation of charge-pump output.
Technical Context
The LM2787BPX integrates a fixed-frequency (260kHz typ.) switched-capacitor inverter stage followed by a low-dropout linear regulator - enabling ripple suppression via high PSRR and precise output regulation. Its dual-stage architecture separates charge-pump noise generation from final output conditioning.
Feedback control operates at VFB = −1.20V (±0.05V), requiring external resistor divider between VOUT, VFB, and VADJ (GND to VIN). Shutdown disconnects internal switches and grounds VOUT/VNEG, reducing supply current to 0.05µA while preserving output capacitor charge state.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | +2.7V to +5.5V - supports single-cell Li-ion and 3.3V/5V system rails without pre-regulation. |
| Output Voltage Range | Adjustable −1.5V to −5.2V - set via external resistor divider; enables GaAsFET bias tuning across process/voltage corners. |
| Max Output Current | 10mA - sufficient for RF power amplifier bias in GSM/EDGE/WCDMA front-ends. |
| Switching Frequency | 260kHz (typ.) - balances EMI, capacitor size, and output resistance; avoids AM radio band interference. |
| Output Ripple | 1mV (at 2.5mA, −2.7V) - low enough to avoid AM modulation distortion in sensitive RF stages. |
| Shutdown Current | 0.05µA (typ.) - enables battery-critical sleep modes in portable transceivers without leakage penalty. |
| Power Efficiency | 91% (at 10mA) - minimizes thermal rise in space-constrained DSBGA-8 package on PCB. |
Pinout & Package
LM2787BPX uses an 8-bump DSBGA (Die Size Ball Grid Array) package with 0.5mm pitch, NSMD pad layout, and bottom-side thermal path - optimized for ultra-thin mobile applications. Mounting requires reflow profile per AN1112.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1 | Cap+ | Positive terminal of flying capacitor C1 - connects to internal switch node during charge phase. |
| B1 | VIN | Main positive input supply - powers both charge-pump and LDO stages; must be bypassed near pin. |
| C1 | VOUT | Regulated negative output - provides stable bias to RF amplifiers; PSRR attenuates charge-pump ripple. |
| C2 | VFB | Feedback input - held at −1.20V reference; sets output via resistor divider to VADJ (typically GND). |
| C3 | SD | Active-low shutdown control - logic-compatible with 1.8V/3.3V GPIO; pulls VOUT/VNEG to GND when asserted. |
| B3 | VNEG | Unregulated negative output - raw inverted voltage prior to LDO; used only if regulation not required. |
| A3 | Cap− | Negative terminal of flying capacitor C1 - completes charge-transfer loop with Cap+. |
| A2 | GND | Analog ground reference - shared return for VIN, VOUT, VFB, SD, and Cap−; critical for noise control. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated LDO post-regulator | Reduces charge-pump ripple by >40dB via PSRR - eliminates need for external LC filtering in RF bias paths. |
| Adjustable output via VFB | Enables precise −2.5V to −3.3V GaAsFET gate bias without trimming resistors or custom variants. |
| DSBGA-8 footprint | 0.95mm × 1.25mm body size - saves >70% board area vs. SOIC-8, critical for antenna-proximate layouts. |
| Low-noise startup | 120–600µs start-up time with monotonic VOUT ramp - prevents RF stage turn-on glitches during power sequencing. |
| ESD-hardened design | 2kV HBM rating - withstands handling in high-volume mobile assembly without special ESD protocols. |
Applications
| Cellular Phone Power Amplifier Biasing | Wireless Communication Systems |
|---|---|
Use Scenario: Providing stable negative gate bias to GaAsFET power amplifiers in GSM/UMTS/LTE handsets during transmit bursts. IC Role / Device Role / Timing Role: Regulated negative voltage source with fast transient response and ultra-low ripple to prevent AM-to-PM distortion. Use Value: Enables 30dB ACLR compliance in WCDMA PA stages by maintaining <1mV ripple under 10mA pulsed load. |
Use Scenario: Generating clean −3.3V bias for RF front-end ICs (LNAs, mixers, switches) in Wi-Fi 6/Bluetooth 5 modules. IC Role / Device Role / Timing Role: Low-noise inverter supplying isolated negative rail independent of main system supply noise. Use Value: Eliminates need for discrete inductor-based inverters, reducing BOM count and EMI emissions in compact IoT radios. |
| Interface Power Supplies | Handheld Instrumentation |
Use Scenario: Powering RS-232 transceivers or analog switch bias networks requiring ±5V rails from single 3.3V supply. IC Role / Device Role / Timing Role: Compact, capacitor-only inverter delivering regulated negative rail without magnetics or transformers. Use Value: Achieves <50mV line/load regulation over temperature - ensures consistent interface voltage margins across operating range. |
Use Scenario: Supplying negative reference voltage for precision ADC drivers and op-amp signal conditioning in portable DMMs. IC Role / Device Role / Timing Role: Low-drift, low-noise auxiliary supply supporting 16-bit measurement accuracy. Use Value: Delivers <10µV p-p noise floor at 10Hz–100kHz - preserves SNR in battery-powered metrology front-ends. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar regulated negative voltage inverter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX680ESA+ | Unregulated inverter; no LDO stage; 120kHz switching; higher output ripple (15mV) | Lacks PSRR filtering - unsuitable for RF bias where ripple directly modulates carrier | Choose only for non-RF applications where cost > performance; requires external LDO for clean bias |
| TPS60403DBVR | Regulated inverter with 2.5V fixed output; no adjustable VFB; 500kHz switching; 2.5mA max current | Fixed −2.5V output limits GaAsFET gate voltage optimization across process corners | Select when fixed output suffices and higher switching frequency allows smaller capacitors |
Compared with MAX680ESA+ and TPS60403DBVR, the LM2787BPX uniquely combines adjustable regulation, integrated LDO ripple suppression, and 10mA drive in a 0.95mm × 1.25mm DSBGA - making it the only option meeting cellular PA bias requirements without external components.
Availability
LM2787BPX is available at Aetrix Electronics and suitable for cellular phone power amplifier biasing, wireless communication systems, and handheld instrumentation requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM2787BPX 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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-reliability, low-power IC design.
The LM2787BPX belongs to TI's regulated charge-pump inverter product line, engineered specifically for noise-sensitive RF bias applications in space-constrained portable electronics.
FAQ
What is the function of the VFB pin on the LM2787BPX?
The VFB pin on the LM2787BPX serves as the feedback input for the internal LDO regulator, held at a precise −1.20V reference. It connects to a resistor divider between VOUT and VADJ (typically GND) to set the regulated output voltage across the −1.5V to −5.2V range. This pin draws only 10nA to 100nA, enabling high-impedance resistor networks without significant error.
Can the LM2787BPX operate from a 2.7V input supply?
Yes, the LM2787BPX operates from a minimum input voltage of +2.7V, supporting single-cell lithium-ion batteries and low-voltage system rails. At 2.7V input, it maintains regulation down to −1.5V output with full 10mA capability, though dropout margin decreases - requiring careful capacitor selection to limit ROUT and maintain stability.
How does the LM2787BPX achieve low output ripple compared to unregulated charge pumps?
The LM2787BPX achieves low output ripple by combining a switched-capacitor inverter stage with a post-regulating LDO. The LDO provides high PSRR (>40dB at 260kHz), attenuating the fundamental switching ripple and harmonics generated by the charge pump. Measured ripple is just 1mV at 2.5mA, far below unregulated alternatives like the MAX680ESA+ (15mV).
What is the recommended capacitor configuration for the LM2787BPX?
Texas Instruments specifies 1.0µF ceramic capacitors (C1, C2, C3) with ≤0.3Ω ESR for optimal LM2787BPX performance. C1 is the flying capacitor; C2 filters VNEG; C3 is the output capacitor. Larger values or lower-ESR types further reduce output resistance and ripple but are not required for basic operation - all capacitors must be surface-mount ceramic, chip tantalum, or polymer electrolytic.
Is the LM2787BPX pin-compatible with other TI charge-pump inverters?
No, the LM2787BPX is not pin-compatible with other TI charge-pump inverters such as the TPS60403DBVR or LM27761YFQR. Its DSBGA-8 pinout (Cap+, VIN, VOUT, VFB, SD, VNEG, Cap−, GND) is unique to this family and differs in both pin assignment and functional allocation - requiring dedicated PCB layout and not supporting drop-in replacement.
LM2787BPX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-VFBGA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Negative
- Topology:
- Charge Pump
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- -1.5V
- Voltage - Output (Max):
- -5.2V
- Current - Output:
- 10mA
- Frequency - Switching:
- 260kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-uSMD
LM2787BPX FAQ
1.How can I place an order for LM2787BPX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2787BPX 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 LM2787BPX reliable?
The price and inventory of LM2787BPX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2787BPX is usually 5 days.
3.What payment methods are accepted for LM2787BPX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2787BPX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2787BPX?
LM2787BPX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2787BPX 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 LM2787BPX?
For technical support, including LM2787BPX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2787BPX requirements.
6.How does Aetrix verify that LM2787BPX is sourced from the original manufacturer or authorized distributors?
All LM2787BPX 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 LM2787BPX meets industry standards.
7.What is the process for return or replacement of LM2787BPX?
All LM2787BPX units undergo pre-shipment inspection (PSI). If there is an issue with LM2787BPX, 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 LM2787BPX part is unused and in its original packaging.
Return procedure for LM2787BPX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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