LTM2886 datasheet(25/38 Pages) LINER

25 / 38 page

LTM2886

2886fb

For more information www.linear.com/LTM2886

APPLICATIONS INFORMATION

Figure 15. V+ Output Noise Spectral Density Without Filter

Figure 16. V+ Output Noise Spectral Density With Filter

RF, Magnetic Field Immunity

TheisolatorµModuletechnologyusedwithintheLTM2886

hasbeenindependentlyevaluated,andsuccessfullypassed

the RF and magnetic field immunity testing requirements

per European Standard EN 55024, in accordance with the

following test standards:

EN 61000-4-3

Radiated, Radio-Frequency,

Electromagnetic Field Immunity

EN 61000-4-8

Power Frequency Magnetic Field

Immunity

EN 61000-4-9

Pulsed Magnetic Field Immunity

Tests were performed using an unshielded test card de-

signed per the data sheet PCB layout recommendations.

Specific limits per test are detailed in Table 5.

Table 4. EMC Immunity Tests

TEST

FREQUENCY

FIELD STRENGTH

EN 61000-4-3 Annex D

80MHz to 1GHz

10V/m

1.4MHz to 2GHz

3V/m

2GHz to 2.7GHz

1V/m

EN 61000-4-8 Level 4

50Hz and 60Hz

30A/m

EN 61000-4-8 Level 5

60Hz

100A/m*

EN 61000-4-9 Level 5

Pulse

1000A/m

*non IEC method

PCB Layout

The high integration of the LTM2886 makes PCB layout

very simple. However, to optimize its electrical isolation

characteristics, EMI, and thermal performance, some

layout considerations are necessary.

• Under heavily loaded conditions VCC and GND current

can exceed 300mA. Sufficient copper must be used

on the PCB to insure resistive losses do not cause the

supply voltage to drop below the minimum allowed

level. Similarly, the VCC2 and GND2 conductors must

be sized to support any external load current. These

heavy copper traces will also help to reduce thermal

stress and improve the thermal conductivity.

• Input and output supply decoupling is not required,

since these components are integrated within the

package. An additional bulk capacitor with a value of

6.8µF to 22µF is recommended. The high ESR of this

capacitor reduces board resonances and minimizes

voltage spikes caused by hot plugging of the supply

voltage. For EMI sensitive applications, an additional

low ESL ceramic capacitor of 1µF to 4.7µF, placed as

close to the power and ground terminals as possible,

is recommended. Alternatively, a number of smaller

value parallel capacitors may be used to reduce ESL

and achieve the same net capacitance.

• Do not place copper on the PCB between the inner

columns of pads. This area must remain open to

withstand the rated isolation voltage.

• The use of solid ground planes for GND and GND2

is recommended for non-EMI critical applications to

optimize signal fidelity, thermal performance, and to

minimize RF emissions due to uncoupled PCB trace

FREQUENCY (kHz)

0.01

0.1

0.01

100

1000

2886 F15

10000

NO LOAD

LOAD = 50

LTM2886-5

FREQUENCY (kHz)

0.01

0.1

0.01

100

1000

2886 F16

10000

LTM2886-5

LOAD = 50

NO LOAD

LTM2886 Datasheet(PDF) 25 Page - Linear Technology

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