STMICROELECTRONICS KBMF01SC6

KBMF
®
IPAD™
EMI FILTER AND LINE TERMINATION
FOR PS/2 MOUSE OR KEYBOARD PORTS
MAIN APPLICATIONS
EMI Filter and line termination for mouse and keyboard ports on:
■
■
■
■
Desktop computers
Notebooks
Workstations
Servers
FEATURES
■ Integrated low pass filters for Data and Clock
lines
■ Integrated ESD protection
■ Integrated pull-up resistors
■ Small package size
■ Breakdown voltage: VBR = 6V min.
DESCRIPTION
SOT23-6L
(Plastic)
Table 1: Order Code
Part Number
KBMF01SC6
■
■
■
EMI / RFI noise suppression
ESD protection exceeding IEC61000-4-2 level 4
High flexibility in the design of high density
boards
KM1
Figure 1: Functional Diagram
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.
BENEFITS
Marking
+Vcc
Rp
Rs
Dat Out
Dat In
C
C
+Vcc
Gnd
+Vcc
Rp
Rs
Clk In
Clk Out
C
C
Rs
Rp
C
Code 01
39Ω
4.7kΩ
120pF
Tolerance
±10%
±10%
±20%
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)
TM: IPAD is a trademark of STMicroelectronics.
October 2004
REV. 2
1/8
KBMF
Table 2: Absolute Maximum Ratings (Tamb = 25°C)
Symbol
VPP
Tj
Tstg
Parameter
Value
Unit
ESD discharge R = 330W C = 150pF contact discharge
ESD discharge - MIL STD 883 - Method 3015-6
±12
±25
kV
Junction temperature
150
°C
- 55 to +150
°C
260
°C
0 to 70
°C
100
mW
Storage temperature range
TL
Lead solder temperature (10 second duration)
Top
Operating temperature Range
Pr
Power rating per resistor
Table 3: Electrical Characteristics (Tamb = 25°C)
Symbol
IR
VBR
VF
Parameters
Test conditions
Diode leakage current
VRM = 5.0V
Diode breakdown voltage
IR = 1mA
Diode forward voltage drop
IF = 50mA
Min
Typ
Max
Unit
10
µA
6
V
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
50 Ω
-10
TEST BOARD
TG OUT
RF IN
KM1
Vg
50 Ω
-20
-30
-40
1
10
100
F (MHz)
2/8
1000
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:
Voutput = VBR + Rd.IPP
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 Voutput level.
Figure 4: ESD clamping behavior
Rg
S1
Rd
VPP
ESD Surge
VBR
Rs
S2
Rd
Vinput
Rload
Voutput
VBR
KBMFxxSC6
Device
to be
protected
To have a good approximation of the remaining voltages at both Vinput and Voutput stages, we give the
typical dynamical resistance value Rd. By taking into account these following hypothesis : Rt>Rd, Rg>Rd
and Rload>Rd, it gives these formulas:
R g ⋅ V BR + R d ⋅ V g
V input = -----------------------------------------------------Rg
R s ⋅ V BR + R d ⋅ V input
V output = ----------------------------------------------------------------Rt
The results of the calculation done for VPP=8kV, Rg=330Ω (IEC 61000-4-2 standard), VBR=7V (typ.) and
Rd = 1Ω (typ.) give:
Vinput = 31.2 V
Voutput = 7.8 V
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 RS.
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
- Voutput clamping voltage very close to VBR (positive strike) and -VF (negative strike)
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KBMF
Figure 5: Measurement conditions
ESD
SURGE
Vin
KM1
16kV
Air
Discharge
TEST BOARD
Vout
Figure 6: Remaining voltage at both stages S1 (Vinput) and S2 (Voutput) during ESD surge
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.
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KBMF
4. CROSSTALK BEHAVIOR
Figure 7: Crosstalk phenomena
RG1
Line 1
VG1
RL1
RG2
α1VG1 + β12VG2
Line 2
VG2
RL2
DRIVERS
α2VG2 + β21VG1
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 RL2 is α2VG2, in fact the real voltage at this point has got an extra value
β21VG1. This part of the VG1 signal represents the effect of the crosstalk phenomenon of the line 1 on the
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
Figure 9: Typical Analog Crosstalk measurement
crosstalk (dB)
0
-20
50 Ω
TEST BOARD
TG OUT
-40
RF IN
KM1
Vg
50 Ω
-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.
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KBMF
Figure 10: Digital crosstalk measurements
configuration
+5V
Figure 11:Digital crosstalk measurements
+5V
74HC04
74HC04
Line 1
Square
Pulse
Generator
5KHz
+5V
VG1
KBMF
01SC6
Line 2
b21 VG1
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
PS/2 Connector
PS/2 Keyboard
Vcc
MDAT
MCLK
KBMF
01SC6
PS/2 Mouse
Super I/O
The KBMF01SC6 device could be used on PS/2 mouse or keyboard as indicated by figure 12.
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KBMF
Figure 13: SOT23-6L Package Mechanical Data
DIMENSIONS
REF.
A2
b
A1
L
H
Min.
A
D
E
Millimeters
c
e
e
Min.
Typ.
Max.
A
0.90
0
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
1.45 0.035
0.057
0.10
0.004
0
0.95
0.037
H
2.60
3.00 0.102
0.118
L
0.10
0.60 0.004
0.024
θ
Figure 14: SOT23-6L Foot print dimensions
(in millimeters)
Max.
A1
e
θ
Typ.
Inches
10°
10°
Table 4: Mechanical Specifications
Lead plating
Tin-lead
Lead plating thickness
5µm min.
25µm max.
Lead material
Sn / Pb
(70% to 90%Sn)
Lead coplanarity
10µm max
Body material
Molded epoxy
Flammability
UL94V-0
0.60
1.20
3.50
2.30
0.95
1.10
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
Feb-2003
1D
28-Oct-2004
2
Description of Changes
Last update.
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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