The LM4120 device is an accurate low-power, low-fall-band gap voltage reference with an output current source and reception capability up to 5 ma in a standard 5-pin SOT-23 package. The input power of this series of reference devices is down to 2v and up to 12v, consuming 160 μa (typical) supply current. In power-off mode, the device current drops to less than 2 μA.
LM4120 Pin Configuration
The LM4120 is available in two grades (Class A and Standard) and seven voltage options for greater flexibility. The best-stage device (A) has an initial accuracy of 0.2%, while the standard device has an initial accuracy of 0.5%, ranging from −40°C to 125°C, all with temperature coefficients of 50 ppm/°C.
The extremely low step-down, low supply current, and power outage capabilities of the LM4120 make the product ideal for battery-powered and portable applications. Equipment performance is guaranteed in the industrial temperature range (-40 ℃~ 85℃) and in the extended temperature range (-40 ℃~ 125℃).
Detailed Description
Overview
The LM4120 device is an accurate bandgap voltage reference, available in 7 different voltage options with current source and reception capabilities up to 5 ma. This family of reference devices can operate at input voltages ranging from 2v to 12v, while consuming 160 μa (typical) of supply current. In power-off mode, the device current drops to less than 2 μA. The LM4120 is available in two grades, Grade A and Standard. The best-stage device (A) has an initial accuracy of 0.2% with a TEMPCO of 50 ppm/°C, ensuring from −40°C to 125°C.
Functional Block Diagram
Feature Description
Enable
ENABLE analog input pins with limited hysteresis typically require 6 μA(typical) current to start the component. The Enable pin must be connected to the VIN pin during normal operation. The minimum conversion rate of this pin is about 0.003V /μs to prevent failure on the output. All of these conditions can be easily satisfied with normal CMOS or TTL logic.
Enable pins can also remotely operate the LM4120 by pulling the enable pin voltage to the input voltage level. To remotely shut down the LM4120, pull the enable pin to the ground. Floating this pin is not recommended.
Layout Guidelines
Due to the mechanical stress of PC board installation, the output voltage will be offset from its initial value. The center of a PC board usually has the highest mechanical and thermal expansion stress. Install the device near the edge or corner of the plate where the mechanical stress is minimal. References in SOT packages are generally less susceptible to assembly stresses than devices in small profile (SOIC) packages.
Mechanical isolation of the device is achieved by creating islands by cutting U-slots on the PCB during installation, helping to reduce the impact of PC board stress on the reference output voltage. This method can also provide some thermal isolation from the rest of the circuit.
The following figure shows the recommended printed board layout for the LM4120 and accompanying drawings. The figure shows the three side slot cuts of the reference IC, which provides an IC that relieves stress on the external PCB.
A typical LM4120 layout example
Features
● Small sot32-5 Small package
● Low drop voltage :120 mV typical at 1 mA
● High output voltage accuracy :0.2%
● Source-sink current output :±5 mA
● Supply current :160 μA typical
● Low temperature factor :50 ppm/°C
● Enable pins
● Fixed output voltage :1.8,2.048,2.5,3,3.3,4.096 and 5 V
● Industrial temperature range :−40°C to 85°C
● (For the extended temperature range, −40°C to 125°C, contact TI)
Applications
● Portable battery powered device
● Instrumentation and process control
● Automotive and industrial
● Test equipment
● Data acquisition system
● Precision regulator
● Battery charger
● Base station
● Communication
● Medical equipment
