LM4140CCM-2.5 datasheet(10/15 Pages) NSC

Part #	LM4140CCM-2.5

Description	High Precision Low Noise Low Dropout Voltage

Download	15 Pages

Scroll/Zoom	100%

Manufacturer	NSC [National Semiconductor (TI)]

Direct Link	http://www.national.com

Logo

10 / 15 page

Application Hints (Continued)

MULTILAYER CERAMIC CAPACITORS

Surface-mountable multilayer ceramic capacitors may be an

attractive choice because of their relatively small physical

size and excellent RF characteristics.

However, they sometimes have an ESR values lower than

the minimum required by the LM4140, and relatively large

capacitance change with temperature. The manufacturer’s

datasheet for the capacitor should be consulted before se-

lecting a value. Test results of LM4140 stability using multi-

layer ceramic capacitors show that a minimum of 0.2µF is

usually needed.

Multilayer ceramic capacitors that have been verified as

suitable for use with the LM4140 are shown in Table 2.

TABLE 2. Surface-Mount Ceramic Capacitors Selection

Guide

2.2µF Surface-Mount Ceramic

Manufacturer

Part Number

Tokin

1E225ZY5U-C203

Murata

GRM42-6Y5V225Z16

4.7µF Surface-Mount Ceramic

Tokin

1E475ZY5U-C304

REVERSE CURRENT PATH

The P-channel Pass transistor used in the LM4140 has an

inherent diode connected between the V

IN and VREF pins

(see diagram below).

10107903

Forcing the output to voltages higher than the input, or

pulling V

IN below voltage stored on the output capacitor by

more than a V

be, will forward bias this diode and current will

flow from the V

REF terminal to VIN. No damage to the

LM4140 will occur under these conditions as long as the

current flowing into the output pin does not exceed 50mA.

ON/OFF OPERATION

The LM4140 is designed to quickly reduce both V

REF and IQ

to zero when turned-off. V

REF is restored in less than 200µs

when turned-on. During the turn-off, the charge across the

output capacitor is discharged to ground through internal

circuitry.

The LM4140 is turned-off by pulling the enable input low, and

turned-on by driving the input high. If this feature is not to be

used, the enable pin should be tied to the V

IN to keep the

reference on at all times (the enable pin must not be left

floating).

To ensure proper operation, the signal source used to drive

the enable pin must be able to swing above and below the

specified high and low voltage thresholds which guarantee

an ON or OFF state (see Electrical Characteristics).

The ON/OFF signal may come from either a totem-pole

output, or an open-collector output with pull-up resistor to the

LM4140 input voltage. This high-level voltage may exceed

the LM4140 input voltage, but must remain within the Abso-

lute Maximum Rating for the enable pin.

OUTPUT ACCURACY

Like all references, either series or shunt, the after assembly

accuracy is made up of primarily three components: initial

accuracy itself, thermal hysteresis and effects of the PCB

assembly stress.

LM4140 provides an excellent output initial accuracy of 0.1%

and temperature coefficient of 6ppm/˚C (B Grade).

For best accuracy and precision, the LM4140 junction tem-

perature should not exceed 70˚C.

The thermal hysteresis curve on this datasheet are perfor-

mance characteristics of three typical parts selected at ran-

dom from a sample of 40 parts.

Parts are mounted in a socket to minimize the effect of

PCB’s mechnical expansion and contraction. Readings are

taken at 25˚C following multiple temperature cycles to 0˚C

and 70˚C. The labels on the X axis of the graph indicates the

device temperature cycle prior to measurement at 25˚C.

The mechanical stress due to the PCB’s mechanical and

thermal stress can cause an output voltage shift more than

the true thermal coefficient of the device. References in

surface mount packages are more susceptible to these

stresses because of the small amount of plastic molding

which support the leads.

Following the recommendations on PCB Layout Consider-

ation section can minimize the mechanical stress on the

device.

PCB LAYOUT CONSIDERATION

The simplest ways to reduce the stress related shifts are:

1.

Mounting the device near the edges or the corners of the

board where mechanical stress is at its minimum. The

center of the board generally has the highest mechani-

cal and thermal expansion stress.

2.

Mechanical isolation of the device by creating an island

by cutting a U shape slot on the PCB for mounting the

device. This approach would also provide some thermal

isolation from the rest of the circuit.

Figure 5 is a recommended printed board layout with a slot

cut on three sides of the circuit layout to serve as a strain

relief.

10107933

FIGURE 4. Typical Thermal Hysteresis

www.national.com

10

Similar Part No. - LM4140CCM-2.5

Manufacturer	Part #	Datasheet	Description
National Semiconductor ...	LM4140CCM-2.5	439Kb / 15P	High Precision Low Noise Low Dropout Voltage
Texas Instruments	LM4140CCM-2.5	1Mb / 23P	[Old version datasheet] High Precision Low Noise Low Dropout Voltage Reference
Texas Instruments	LM4140CCM-2.5/NOPB	1Mb / 23P	[Old version datasheet] High Precision Low Noise Low Dropout Voltage Reference

More results

Similar Description - LM4140CCM-2.5

Manufacturer	Part #	Datasheet	Description
National Semiconductor ...	LM4140	439Kb / 15P	High Precision Low Noise Low Dropout Voltage
Texas Instruments	LM4140	1Mb / 23P	[Old version datasheet] High Precision Low Noise Low Dropout Voltage Reference
Texas Instruments	LM4132	1Mb / 41P	[Old version datasheet] Precision Low Dropout Voltage Reference
New Japan Radio	NJM2863	134Kb / 7P	Ultra Low Noise Low Dropout Voltage Regulator
Nisshinbo Micro Devices...	RX5RZ	716Kb / 20P	LOW DROPOUT AND LOW NOISE VOLTAGE REGULATOR
ams AG	AS13986	650Kb / 13P	Dual Low-Noise, Low-Dropout Voltage Regulator
RICOH electronics devic...	RX5RZ	552Kb / 19P	LOW DROPOUT AND LOW NOISE VOLTAGE REGULATOR
Maxim Integrated Produc...	MAX6070	6Mb / 26P	Low-Noise, High-Precision Series Voltage References 2020
	MAX6070	2Mb / 24P	Low-Noise, High-Precision Series Voltage References Rev 2; 3/13
	MAX6070	5Mb / 26P	Low-Noise, High-Precision Series Voltage References 19-6355; Rev 12; 3/19

More results

LM4140CCM-2.5 Datasheet(PDF) 10 Page - National Semiconductor (TI)

LM4140CCM-2.5 Datasheet(HTML) 10 Page - National Semiconductor (TI)

Similar Part No. - LM4140CCM-2.5

Similar Description - LM4140CCM-2.5

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Datasheet Download

Link URL