Datasheet KBMF Datasheet (ST)

®

EMI FILTER AND LINE TERMINATION

IPAD™

MAIN APPLICATIONS

EMI Filter and line termination for mouse and key­board ports on:

■ Desktop computers

■ Notebooks

■ Workstations

■ Servers

FOR PS/2 MOUSE OR KEYBOARD PORTS

KBMF

FEATURES

■ Integrated low pass filters for Data and Clock

lines

■ Integrated ESD protection

■ Integrated pull-up resistors

■ Small package size

■ Breakdown voltage: V

= 6V min.

BR

DESCRIPTION

On the implementation of computer systems, the
radiated and conducted EMI should be kept within
the required levels as stated by the FCC
regulations. In addition to the requirements of
EMC compatibility, the computing devices are
required to tolerate ESD events and remain
operational without user intervention.
The KBMF implements a low pass filter to limit EMI
levels and provide ESD protection which exceeds
IEC 61000-4-2 level 4 standard. The device also
implements the pull up resistors needed to bias
the data and clock lines. The package is the
SOT23-6L which is ideal for situations where
board space is at a premium.

SOT23-6L

(Plastic)

Table 1: Order Code

Part Number Marking

KBMF01SC6 KM1

Figure 1: Functional Diagram

+Vcc

Dat In

Gnd

Clk In

Rs

CRpC

+Vcc

Rs

CRpC

Rs Rp C

Code 01 39Ω 4.7kΩ 120pF

Tolerance ±10% ±10% ±20%

Dat Out

+Vcc

Clk Out

BENEFITS

■ EMI / RFI noise suppression

■ ESD protection exceeding IEC61000-4-2 level 4

■ High flexibility in the design of high density

boards

TM: IPAD is a trademark of STMicroelectronics.

October 2004

COMPLIES WITH THE FOLLOWING ESD
STANDARDS:

IEC 61000-4-2 (R = 330Ω C = 150pF)

Level 4 ±15 kV (air discharge)

±8 kV (contact discharge)

MIL STD 883C, Method 3015-6

Class 3 C = 100pF R = 1500Ω

3 positive strikes and
3 negative strikes (F = 1 Hz)

REV. 2

1/8

KBMF

Table 2: Absolute Maximum Ratings (T

amb

= 25°C)

Symbol Parameter Value Unit

V

PP

T

j

T

stg

T

L

T

op

P

r

ESD discharge R = 330W C = 150pF contact discharge
ESD discharge - MIL STD 883 - Method 3015-6

Junction temperature 150 °C

Storage temperature range - 55 to +150 °C

Lead solder temperature (10 second duration) 260 °C

Operating temperature Range 0 to 70 °C

Power rating per resistor 100 mW

Table 3: Electrical Characteristics (T

amb

= 25°C)

±12
±25

kV

Symbol Parameters Test conditions Min Typ Max Unit

I

R

V

BR

V

F

Diode leakage current

Diode breakdown voltage

Diode forward voltage drop

= 5.0V

V

RM

= 1mA

I

R

= 50mA

I

F

10 µA

6V

0.9 V

TECHNICAL INFORMATION

1. EMI FILTERING

The KBMFxxSC6 ensure a filtering protection against ElectroMagnetic and RadioFrequency Interferences
thanks to its low-pass filter structure. This filter is characterized by the following parameters :

- cut-off frequency

- Insertion loss

- high frequency rejection

Figure 2: Measurements configuration Figure 3: KBMF attenuation curve

Insertion loss (dB)

0

-10

-20

-30

-40
1 10 100 1000

F (MHz)

2/8

TG OUT

50 Ω

Vg

TEST BOARD

KM1

RF IN

50 Ω

KBMF

2. ESD PROTECTION

The KBMFxxSC6 is particularly optimized to perform ESD protection. ESD protection is based on the use
of device which clamps at:

V

= VBR + Rd.I

output

This protection function is splitted in 2 stages. As shown in figure 4, the ESD strikes are clamped by the
first stage S1 and then its remaining overvoltage is applied to the second stage through the resistor R.
Such a configuration makes the output voltage very low at the V

Figure 4: ESD clamping behavior

PP

output

level.

Rg

V

PP

ESD Surge

To have a good approximation of the remaining voltages at both V

V

Rd

BR

S1

Rs

Vinput

Voutput

KBMFxxSC6

S2

Rd

V

input

BR

and V

Rload

Device

to be

protected

stages, we give the

output

typical dynamical resistance value Rd. By taking into account these following hypothesis : R
and R

load>Rd

, it gives these formulas:

V

V

input

output

RgV

=

RsV

=

-----------------------------------------------------------------

BRRdVg

-----------------------------------------------------­R

g

BRRdVinput

R

t

⋅+⋅

⋅+⋅

t>Rd

, Rg>R

d

The results of the calculation done for V
R

= 1Ω (typ.) give:

d

V

input

V

output

= 31.2 V

= 7.8 V

=8kV, Rg=330Ω (IEC 61000-4-2 standard), VBR=7V (typ.) and

PP

This confirms the very low remaining voltage across the device to be protected. It is also important to note
that in this approximation the parasitic inductance effect was not taken into account. This could be few
tenths of volts during few ns at the input side. This parasitic effect is not present at the output side due the
low current involved after the resistance R

.

S

The measurements done here after show very clearly (figure 6) the high efficiency of the ESD protection :

- no influence of the parasitic inductances on output stage

- V

clamping voltage very close to VBR (positive strike) and -VF (negative strike)

output

3/8

KBMF

Figure 5: Measurement conditions

ESD

SURGE

16kV

Air

Discharge

TEST BOARD

KM1

Vin

Vout

Figure 6: Remaining voltage at both stages S1 (V

) and S2 (V

input

) during ESD surge

output

Positive surge Negative surge

Please note that the KBMF01SC6 is not only acting for positive ESD surges but also for negative ones.
For these kind of disturbances it clamps close to ground voltage as shown in the Negative Surge figure.

3. LATCH-UP PHENOMENA

The early ageing and destruction of IC’s is often due to latch-up phenomena which is mainly induced by
dV/dt. Thanks to its structure, the KBMF01SC6 provides a high immunity to latch-up phenomena by
smoothing very fast edges.

4/8

4. CROSSTALK BEHAVIOR

Figure 7: Crosstalk phenomena

R

G1

V

G1

R

G2

V

G2

Line 1

Line 2

KBMF

R

L1

R

L2

αβ

αβ

V+ V

1G1 12G2

V+ V

2G2 21G1

DRIVERS

RECEIVERS

The crosstalk phenomena is due to the coupling between 2 lines. The coupling factor ( β12 or β21 )
increases when the gap across lines decreases, this is the reason why we provide crosstalk
measurements for monolithic device to guarantee negligeable crosstalk between the lines. In the example
above the expected signal on load R

β

. This part of the VG1 signal represents the effect of the crosstalk phenomenon of the line 1 on the

21VG1

is α2VG2, in fact the real voltage at this point has got an extra value

L2

line 2. This phenomenon has to be taken into account when the drivers impose fast digital data or high
frequency analog signals in the disturbing line. The perturbed line will be more affected if it works with low
voltage signal or high load impedance (few kΩ).

Figure 8: Analog Crosstalk measurements
configuration

TG OUT

50 Ω

Vg

TEST BOARD

KM1

RF IN

50 Ω

Figure 9: Typical Analog Crosstalk meas­urement

crosstalk (dB)

0

-20

-40

-60

-80

-100

-120
1 10 100 1,000

F (MHz)

Figure 8 gives the measurement circuit for the analog crosstalk application. In figure 9, the curve shows
the effect of the Data line on the CLK line. In usual frequency range of analog signals (up to 100MHz) the
effect on disturbed line is less than -37dB.

5/8

KBMF

Figure 10: Digital crosstalk measurements

Figure 11:Digital crosstalk measurements

configuration

+5V +5V

Square
Pulse
Generator
5KHz

+5V

74HC04

Line 1

V

G1

Line 2

KBMF

01SC6

74HC04

b

V

21

G1

Figure 10 shows the measurement circuit used to quantify the crosstalk effect in a classical digital appli­cation.
Figure 11 shows that in such a condition signal from 0 to 5V and rise time of few ns, the impact on the
other line is less than 50mV peak to peak (below the logic high threshold voltage). The measurements
performed with falling edges gives the results within the same range.

5. APPLICATION EXAMPLE
Figure 12: Implementation of KBMFxxSC6 in a typical application

KDAT

KCLK

KBMF

01SC6

Vcc

PS/2 Connector

PS/2 Keyboard

Super I/O

MDAT

KBMF

MCLK

01SC6

PS/2 Mouse

The KBMF01SC6 device could be used on PS/2 mouse or keyboard as indicated by figure 12.

6/8

Figure 13: SOT23-6L Package Mechanical Data

A2

A

D

A1

L

H

θ

c

E

b

ee

KBMF

DIMENSIONS

REF.

A 0.90 1.45 0.035 0.057

A1 0 0.10 0 0.004

A2 0.90 1.30 0.035 0.051

b 0.35 0.50 0.014 0.02

C 0.09 0.20 0.004 0.008

D 2.80 3.05 0.110 0.120

E 1.50 1.75 0.059 0.069

e 0.95 0.037

H 2.60 3.00 0.102 0.118

L 0.10 0.60 0.004 0.024

θ 10° 10°

Millimeters Inches

Min. Typ. Max. Min. Typ. Max.

Figure 14: SOT23-6L Foot print dimensions

Table 4: Mechanical Specifications

(in millimeters)

Lead plating Tin-lead

0.60

5µm min.

25µm max.

Sn / Pb

(70% to 90%Sn)

3.50

2.30

0.95

1.20

1.10

Lead plating thickness

Lead material

Lead coplanarity 10µm max

Body material Molded epoxy

Flammability UL94V-0

Table 5: Ordering Information

Ordering code Marking Package Weight Base qty Delivery mode

KBMF01SC6 KM1 SOT23-6L 16.7 mg 3000 Tape & reel

Table 6: Revision History

Date Revision Description of Changes

Feb-2003 1D Last update.

28-Oct-2004 2 SOT23-6L package dimensions change for reference “D”

from 3.0 millimeters (0.118 inches) to 3.05 millimeters
(0.120 inches).

7/8

KBMF

Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences
of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted
by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject
to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not
authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.

The ST logo is a registered trademark of STMicroelectronics.

All other names are the property of their respective owners

© 2004 STMicroelectronics - All rights reserved

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