My Inquiry
My Account
Texas Instruments LM2687MMX
- Part No.:
- LM2687MMX
- Manufacturer:
- Texas Instruments
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM2687MMX.pdf
- Description:
- IC REG CHRG PUMP ADJ 10MA 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,598
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM2687MMX from Texas Instruments is a low-noise, regulated switched-capacitor voltage inverter IC that generates an adjustable negative output (−1.5V to −5.2V) from a +2.7V to +5.5V input supply. It delivers up to 10mA output current with 1mV typical output ripple, 91% typical charge-pump efficiency at 10mA, and operates at 100kHz switching frequency. It is used for GaAsFET power amplifier biasing in cellular phones and portable wireless systems.
For engineers reviewing the LM2687MMX datasheet, LM2687MMX pinout, LM2687MMX application, or LM2687MMX equivalent, key selection considerations include its regulated negative output range, ultra-low 0.05µA shutdown current, MSOP-8 package compatibility, and low-noise performance critical for RF biasing and precision analog interface supplies.
Technical Context
The LM2687MMX integrates a fixed-frequency (100kHz typ.) switched-capacitor inverter stage followed by a low-dropout linear regulator to suppress ripple and noise. Its feedback pin (VFB) maintains a −1.20V reference, enabling precise output regulation via external resistor dividers tied to VADJ (GND to VIN).
It features active-low logic-level shutdown (SD), which disconnects internal switches and grounds both VOUT and VNEG while reducing quiescent current to 0.05µA. The device uses four external capacitors (C1–C3 + bypass) and requires no inductor, making it suitable for space-constrained, low-EMI applications where inductive solutions are prohibited.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | +2.7V to +5.5V - supports single-cell Li-ion, 3.3V, and 5V rail operation without external regulators. |
| Output Voltage Range | −1.5V to −5.2V - adjustable via external resistive divider; enables flexible biasing of GaAsFETs and op-amp rails. |
| Max Output Current | 10mA - sufficient for RF power amplifier bias and low-power analog circuitry. |
| Output Ripple | 1mV typical - achieved via PSRR-enhanced LDO post-regulation; critical for noise-sensitive RF stages. |
| Shutdown Current | 0.05µA typical - enables battery-critical sleep modes in portable devices without leakage penalties. |
| Switching Frequency | 100kHz typical - balances capacitor size, EMI, and efficiency; avoids audible noise and simplifies filtering. |
| Charge-Pump Efficiency | 91% at 10mA - minimizes thermal load and extends battery life in handheld instrumentation. |
Pinout & Package
LM2687MMX is housed in an 8-pin MSOP (MUA08A) package with exposed die attach pad not connected in this variant (LLP variant connects DAP to VNEG). Pinout is identical across LM2687MM/MMX variants.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - Cap+ | Positive terminal of flying capacitor C1 | Connects to C1 anode during charge phase; internal switch node for charge-pump operation. |
| 2 - GND | Ground reference | Primary return path for all internal circuits and external capacitors; must be low-impedance. |
| 3 - Cap− | Negative terminal of flying capacitor C1 | Connects to C1 cathode during discharge phase; completes charge-transfer cycle with Cap+. |
| 4 - SD | Active-low shutdown control | Logic-compatible input; pulls VOUT/VNEG to GND when low; requires pull-up if left undriven. |
| 5 - VNEG | Unregulated negative output of charge pump | Feeds LDO stage; sensitive to capacitor ESR and layout; not intended as final output. |
| 6 - VFB | Feedback input for LDO regulation | Senses −1.20V reference; connects to resistor divider between VOUT and VADJ (typically GND). |
| 7 - VOUT | Regulated negative output | Final system output; low-noise, load- and line-regulated; connects to load and C3 (10µF ceramic). |
| 8 - VIN | Positive input supply | Accepts 2.7–5.5V; powers internal oscillator, switches, and LDO; requires local 1µF bypass. |
Key Features
| Feature | Design Value |
|---|---|
| Regulated negative output | Enables stable, ripple-suppressed bias for GaAsFET amplifiers without external LDO or inductor-based solutions. |
| 1mV typical output ripple | Result of >60dB PSRR LDO stage rejecting charge-pump switching artifacts-critical for RF signal integrity. |
| 0.05µA shutdown current | Reduces standby power to negligible levels in battery-powered handhelds, extending shelf and operational life. |
| MSOP-8 footprint | 8-pin 3mm × 3mm package fits tight PCB real estate; compatible with standard reflow and automated assembly. |
| 100kHz fixed switching | Eliminates EMI concerns above audio band while allowing use of small, low-ESR ceramic capacitors (1µF min). |
Applications
| Cellular Phone Power Amplifier Biasing | Wireless Communication Systems |
|---|---|
Use Scenario: Providing clean, adjustable negative gate bias to GaAsFET power amplifiers in GSM/UMTS handsets. IC Role / Device Role / Timing Role: Regulated negative voltage generator with ultra-low ripple and fast startup for PA enable sequencing. Use Value: Enables high-efficiency PA operation with minimal AM-to-PM distortion by eliminating switching noise coupling into RF paths. |
Use Scenario: Generating isolated negative supply for RF front-end ICs, mixers, and IF amplifiers in Bluetooth/WiFi modules. IC Role / Device Role / Timing Role: Compact, inductorless negative rail generator supporting rapid on/off cycling in burst-mode transceivers. Use Value: Reduces BOM count and board area versus discrete inductor-based inverters while maintaining <1mV noise floor. |
| Interface Power Supplies | Handheld Instrumentation |
Use Scenario: Supplying dual-rail ±2.5V or ±3.3V for RS-232 transceivers, precision ADC drivers, and op-amp signal conditioning. IC Role / Device Role / Timing Role: Low-noise negative rail source synchronized to main system power-up sequence via SD pin control. Use Value: Eliminates need for transformer-isolated or inductor-based supplies, improving reliability and reducing EMI in mixed-signal PCBs. |
Use Scenario: Powering analog front-ends and sensor signal chains in portable multimeters, gas detectors, and medical monitors. IC Role / Device Role / Timing Role: Battery-efficient negative bias generator with shutdown support for intermittent measurement cycles. Use Value: Extends single-cell Li-ion runtime beyond 100 hours by limiting quiescent draw to 0.05µA during idle periods. |
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; fixed −2×VIN output; no LDO stage; higher ripple (~10mV); 125kHz switching. | Lacks output regulation and low-noise capability; unsuitable for GaAsFET bias where voltage stability is critical. | Select only when cost and simplicity outweigh regulation requirements and noise sensitivity. |
| TPS60403DBVR | Regulated inverter with −1.5V to −5.5V range; 1.2MHz switching; 15mA output; 2.5µA quiescent; requires different capacitor values. | Higher switching frequency allows smaller capacitors but increases EMI risk near sensitive RF bands. | Prefer for space-constrained designs needing higher current, but verify RF coexistence in shared PCB layouts. |
Compared with MAX680ESA+ and TPS60403DBVR, the LM2687MMX uniquely balances ultra-low ripple (1mV), sub-µA shutdown, and 100kHz operation-making it optimal for noise-critical RF biasing where EMI and battery life are jointly constrained.
Availability
LM2687MMX is available at Aetrix Electronics and suitable for cellular phone power amplifier biasing, handheld instrumentation, and interface power supplies requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2687MMX 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 company specializing in analog, embedded processing, and connectivity technologies, with leadership in power management and precision analog ICs.
The LM2687MMX belongs to TI's regulated charge-pump inverter product line, designed specifically for low-noise, inductorless negative rail generation in portable RF and precision analog systems.
FAQ
What is the function of the VFB pin on the LM2687MMX?
The VFB pin on the LM2687MMX is the feedback input for the internal low-dropout linear regulator. It senses a −1.20V reference voltage and adjusts the output to maintain regulation via an external resistor divider between VOUT and VADJ (typically GND). This allows precise setting of the LM2687MMX output voltage across its −1.5V to −5.2V range without trimming or calibration.
Can the LM2687MMX operate from a 2.5V input supply?
No, the LM2687MMX cannot reliably operate from a 2.5V input. Its specified operating input voltage range is +2.7V to +5.5V per the absolute maximum ratings and electrical characteristics tables. At 2.5V, the internal oscillator and charge-pump switches may fail to activate, resulting in no output or unstable regulation. Always maintain VIN ≥2.7V for guaranteed LM2687MMX functionality.
What is the recommended capacitor configuration for minimum noise in the LM2687MMX?
For minimum noise, the LM2687MMX requires C1 = C2 = 1µF ceramic (≤0.3Ω ESR), C3 = 10µF ceramic (≤0.3Ω ESR), placed as close as possible to respective pins. C3 must connect directly between VOUT and GND with shortest possible traces. Avoid ground loops by probing VOUT at C3's ground terminal using the oscilloscope probe's grounding ring-not the ground lead-to capture true 1mV typical ripple.
Does the LM2687MMX require an external resistor to set its output voltage?
Yes, the LM2687MMX requires two external resistors (R1 and R2) forming a divider between VOUT, VFB, and VADJ (typically GND) to set its regulated output voltage. The LM2687MMX does not have a fixed output; its −1.5V to −5.2V range is determined by this divider network using the equation VOUT = −VFB × (1 + R1/R2), where VFB = −1.20V. Omitting or misconfiguring these resistors results in loss of regulation.
How does shutdown affect the VOUT and VNEG pins of the LM2687MMX?
When the SD pin of the LM2687MMX is pulled low, the device enters shutdown mode: internal switches disable, the charge pump halts, and both VOUT and VNEG are actively discharged to GND through internal FETs. This ensures no floating or unintended bias remains on connected loads-critical for safe PA bias sequencing. Shutdown reduces total supply current to 0.05µA typical, preserving battery life in portable systems using the LM2687MMX.
LM2687MMX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- 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:
- 110kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-VSSOP
LM2687MMX FAQ
1.How can I place an order for LM2687MMX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2687MMX 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 LM2687MMX reliable?
The price and inventory of LM2687MMX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2687MMX is usually 5 days.
3.What payment methods are accepted for LM2687MMX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2687MMX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2687MMX?
LM2687MMX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2687MMX 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 LM2687MMX?
For technical support, including LM2687MMX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2687MMX requirements.
6.How does Aetrix verify that LM2687MMX is sourced from the original manufacturer or authorized distributors?
All LM2687MMX 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 LM2687MMX meets industry standards.
7.What is the process for return or replacement of LM2687MMX?
All LM2687MMX units undergo pre-shipment inspection (PSI). If there is an issue with LM2687MMX, 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 LM2687MMX part is unused and in its original packaging.
Return procedure for LM2687MMX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM2687MMX Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
