August 2006 Rev 10 1/9
9
USB6B1
Data line protection
Applications
Where transient overvoltage protection in
sensitive equipment is required, such as:
■Universal Serial Bus ports
■RS-423 interfaces
■RS-485 interfaces
■ISDN equipment
■T1/E1 line cards
■HDSL / ASDL interfaces
Features
■Full diode bridge with integrated clamping
protection
■Breakdown voltage: VBR = 6 V min.
■Peak pulse power dissipation: PPP = 500 W
(8/20 µs)
■Very low capacitance, compatible with high
debit data or signal rates.
Description
In order to prevent fast transients from leading to
severe damages in a high speed data system, a
specific protection has been developed by
STMicroelectronics.
The USB6B1 protects the two input lines against
overvoltage. Besides, this device also keeps the
power rails in a safe limit thanks to the integrated
Transil diode.
Benefits
■Provides protection for each line and between
the supply voltage and GND: 25 A, 8/20 µs.
■High ESD protection level: up to level 3 per MIL
STD 883C-Method 3015-6
■Separated inputs and outputs (so-called 4-point
structure) to improve ESD susceptibility.
■Comprehensive package pin-out for immediate
implementation.
Order Codes
Functional diagram
Complies with the following standards:
Part Numbers Marking
USB6B1 USB62
USB6B1RL USB62
MIL STD 883C - Method 3015-6
class 3 C = 100 pF R = 1500 Ω
3 positive strikes and 3 negative strikes (F = 1 Hz)
IEC 61000-4-2 level 4
15 kV (air discharge)
8 kV (contact discharge)
SO-8
VCC VCC
I/O1I/O1
I/O2I/O2
GNDGND
www.st.com
Characteristics USB6B1
2/9
1 Characteristics
Table 1. Absolute maximum ratings
Symbol Parameter Value Unit
VPP Peak pulse voltage
IEC61000-4-2 contact discharge
IEC61000-4-2 air discharge
MIL STD883C-Method 30 15-6
8
15
4
kV
PPP Peak pulse power 8/20 µs 500 W
IPP Peak pulse current 8/20 µs 25 A
2/10 µs 40
Tstg
Top
Storage temperature range
Operating temperature range
- 55 to + 150
- 40 to + 85
° C
° C
TLLead solder temperature (10 s duration) 260 ° C
Table 2. Electrical characteristics (Tamb = 25° C)
Symbol Parameter
Value
Unit
Min Typ Max
VBR Breakdown voltage between VBUS and GND IR = 1 mA 6 V
IRM Leakage current VRM = 5.25 V 10 µA
C
Capacitance between pins D+ and D-
VOSC = 30 mV, F = 1 MHz, VR = 0 V
VCC
not connected 15 pF
Capacitance between pins D+(or D-) and GND
VOSC = 30 mV, F = 1 MHz, VR = 5 V VCC = 5 V 25 pF
USB6B1 Characteristics
3/9
Figure 1. Peak power dissipation versus
initial junction temperature
Figure 2. Relative variation of leakage
current versus junction
temperature (typical values)
Figure 3. Relative variation of breakdown
voltage versus junction temperature
(typical values)
-40 -20 0 20 40 60 80 100 120 140 160
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
P [T initial]/P [T initial=25°C]
pp j pp j
T initial(°C)
j
I [T ] / I [T =25°C]
Rj Rj
-40 -20 0 20 40 60 80 100 120 140
0.1
1.0
10.0
T (°C)
j
-40 -20 0 20 40 60 80 100 120 140
0.90
0.95
1.00
1.05
1.10 V [T ] / V [T =25°C]
BR j BR j
T (°C)
j
Technical information USB6B1
4/9
2 Technical information
2.1 Surge protection
The USB6B1 is optimized to perform surge protection based on the rail to rail topology.
The clamping voltage VCL can be estimated as follow:
VCL+ = VCC + VF for positive surges
VCL - = - VF for negative surges
with: VF =Vt + rd.Ip
VF = forward drop voltage, Vt = forward drop threshold voltage
Note: The estimations do not take into account phenomena due to parasitic inductances.
2.2 How to ensure good ESD protection
While the USB6B1 provides a high immunity to ESD surge, an efficient protection depends
on the layout of the board. In the same way, with the rail to rail topology, the track from the
VCC pin to the power supply and from the GND pin to GND voltage must be as short as
possible to avoid overvoltages due to parasitic phenomena (see Figure 4.)
It’s often harder to connect the power supply near to the USB6B1 unlike the ground thanks
to the ground plane that allows a short connection. To ensure the same efficiency for
positive surges when the connections can’t be short enough, we recommend to putting a
100 nF c apacitor close to the USB6B1 between VCC and ground to prevvent these kinds of
overvoltage disturbances (see Figure 5.) The addition of this capacitor offers better
protection by providing a constant voltage during the surge.
Figure 6. shows the improvement of the ESD protection according to the recommendations
described above.
Important: An imortant precaution to take is to put the protection device closer to the disturbance
source (generally the connection).
Figure 4. Surge behavior Figure 5. ESD behavior: optimized
layout and addition of a
100 nF capacitor
Lw
VI/O
ESD
SURGE
GND
I/O
+Vcc
Vf Lw di
dt
Lw di
dt
Vcl+ = Vcc+Vf+Lw di
dt surge >0
-Vf- Lw di
dt surge <0
Vcl- =
t
tr=1ns
Vcc+Vf
Lw di
dt
Vcl+
POSITIVE
SURGE -Lw di
dt
t
tr=1ns
-Vf
Vcl-
NEGATIVE
SURGE
REF1=GND
VI/O
ESD
SURGE
I/O
REF2=+Vcc
C=100nF
Lw
Vcl+ = Vcc+Vf
-Vf
surge >0
surge <0
Vcl- =
t
Vcl+
POSITIVE
SURGE
t
Vcl-
NEGATIVE
SURGE
USB6B1 Technical information
5/9
2.3 Universal Serial Bus
The data transmission standard, Universal Serial Bus (USB) is being driven by market
leaders in the world of Computer and Telecommunications, including Compaq, DEC,
IBM, Intel, Microsoft, NEC and Nortel, and has become a leading transmission protocol.
This standard mainly provides simplified interconnectivity. Specialized ports on the back of
the present PC will largely be replaced by USB ports. Many peripherals such as printers,
key-boards, monitors and joysticks use USB ports.
The USB offers high speed communication rates up to 480 Mbit/s. Only two wires (D+, D-)
are required for data transfer. Additionally, limited amount of power for USB devices located
on the downstream can also be transmitted on two separate conductors within the same
cable.
2.4 Protection to support USB
Designers dealing with the USB chips are concerned about electrostatic discharge
sensitivity (ESD) of their USB controller ICs.
The USB controller is more than just a driver / receiver; it acts as a microcontroller which
manages power and direct signal traffic. This complexity increases its cost over
conventional devices. Therefore, a failure of a USB port could result in costly computer
failure.
In order to prevent these fast transients from leading to severe damages in a system, a
specific protection has been developed by STMicroelectronics. The USB6Bx protects not
only the two wires of data transmission, but also keep the power rails in a safe limit.
Figure 6. Recommended configuration for USB port protection
The capacitance between the I/O transmission wires provides no significant signal distortion
at the 12 Mbit/s data rate, thus allowing compatibility with USB standard.
Available in a compact SO-8 this protective element requires minimal board space and
eases the PCB layout thanks to its direct compatibility with the USB connector pin-out.
1
USB
IC
VBUS
D+
D-
GND
USB output
connector
Telecom and datacom applications USB6B1
6/9
3 Telecom and datacom applications
Figure 7. ISDN U interface protection
Figure 8. T1 / E1 Line Card Protection.
Figure 9. High Speed Line Driver / Receiver Protection
USB6Bx 3* SMP100
DC Power
Source
LT
+Vcc
RTIP USB6B1
USB6B1
RRING
TTIP
TRING
SMP75-8 or SMP100-8
SMP75-8 or SMP100-8
+Vcc
+Vcc
DRIVER
SM6T6V8A
USB6B1
INPUT
+5V
RECEIVER
SM6T6V8A
USB6B1
OUTPUT
+5V
+Vcc
+Vcc
USB6B1 Ordering information scheme
7/9
4 Ordering information scheme
5 Package information
Epoxy meets UL94, V0
USB 6 B1 RL
USB Protection
Breakdown voltage
Packaging
6 = 6V min.
RL = Tape & reel
Blank = Tube
Package
B1 = SO-8
Table 3. SO-8 dimensions
Ref.
Dimensions
Millimeters Inches
Min. Typ. Max. Min. Typ. Max.
A 1.75 0.069
A1 0.1 0.25 0.004 0.010
A2 1.25 0.049
b 0.28 0.48 0.011 0.019
C 0.17 0.23 0.007 0.009
D 4.80 4.90 5.00 0.189 0.193 0.197
E 5.80 6.00 6.20 0.228 0.236 0.244
E1 3.80 3.90 4.00 0.150 0.154 0.157
e 1.27 0.050
h 0.25 0.50 0.010 0.020
L 0.40 1.27 0.016 0.050
L1 1.04 0.041
k°0808
ccc 0.10 0.004
E1
D
8
41
5
E
k
h x 45°
L
L1
C
(Seating
Plane) 0.25mm
(Gage Plane)
e
A
A2
bA1
ccc C
C
Ordering information USB6B1
8/9
Figure 10. SO-8 footprint (dimensions in mm)
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a lead-free second level interconnect. The category of
second level interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com.
6 Ordering information
7 Revision history
6.8
4.2
1.27
0.6
Ordering code Marking Package Weight Base qty Delivery mode
USB6B1 USB62 SO-8 0.077 g 100 Tube
USB6B1RL USB62 2500 Tape and reel
Date Revision Description of Changes
Oct-2003 6A Previous issue.
03-May-2005 7 Figure 1 on page 1: dots connection corrected.
22-Feb-2006 8 Marking typing error corrected on page 1 and 7.
16-Aug-2006 9 Reformated to current standard. ECOPACK statement
added. SO-8 package dimensions corrected.
USB6B1
9/9
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