srv05-4mr6 ON Semiconductor, srv05-4mr6 Datasheet - Page 6

• Manufacturer Part Number: srv05-4mr6
• Description: Srv05-4mr6 Transient Voltage Suppressors
• Manufacturer: ON Semiconductor

positive ESD condition occurs, diode D1 will be forward
biased while diode D2 will be forward biased when a
negative ESD condition occurs. For slower transient
conditions, this system may be approximated as follows:
For positive pulse conditions:
For negative pulse conditions:
number of nanoseconds. Under these conditions, the effect
of parasitic inductance must be considered. A pictorial
representation of this is shown below.
transients would be:
For positive pulse conditions:
For negative pulse conditions:
only depends on the Vf of the steering diodes but also on the
L d
result in hundreds of volts appearing on the supply rail. This
endangers both the power supply and anything attached to
that rail. This highlights the importance of good board
layout. Taking care to minimize the effects of parasitic
inductance will provide significant benefits in transient
immunity.
Protected
V
Looking at the figure above, it can be seen that when a
Vc = V
Vc = −Vf
ESD events can have rise times on the order of some
Protected
An approximation of the clamping voltage for these fast
Vc = V
Vc = −Vf – (L di
As shown in the formulas, the clamping voltage (Vc) not
Supply
Device
CC
Power
Supply
Device
Power
iESD
/dt factor. A relatively small trace inductance can
CC
CC
D2
Data Line
+ Vf
Data Line
+ Vf + (L di
D1
ESD
V
/dt)
CC
ESD
D1
D2
D2
D1
/dt)
I
I
ESDpos
I
ESDneg
I
V
ESDpos
ESDneg
C
= V
I
I
V
ESDpos
ESDpos
C
CC
= −Vf − (L diESD/dt)
+ Vf + (L diESD/dt)
VF + V
CC
I
I
ESDneg
ESDneg
http://onsemi.com
−VF
6
present when discrete diodes are used to suppress ESD
events across datalines and the supply rail. Discrete diodes
with good transient power capability will have larger die and
therefore higher capacitance. This capacitance becomes
problematic as transmission frequencies increase. Reducing
capacitance generally requires reducing die size. These
small die will have higher forward voltage characteristics at
typical ESD transient current levels. This voltage combined
with the smaller die can result in device failure.
overcome the disadvantages encountered when using
discrete diodes for ESD protection. This device integrates a
TVS diode within a network of steering diodes.
to ground through the TVS diode as shown below.
be:
Figure 7 and depends on the magnitude of the ESD current.
The steering diodes are fast switching devices with unique
forward voltage and low capacitance characteristics.
Even with good board layout, some disadvantages are still
The ON Semiconductor SRV05−4MR6 was developed to
During an ESD condition, the ESD current will be driven
The resulting clamping voltage on the protected IC will
Vc = VF + V
The clamping voltage of the TVS diode is provided in
Figure 8. SRV05−4MR6 Equivalent Circuit
V
Protected
CC
Supply
Device
Power
TVS
D1
D2
.
Data Line
D3
D4
D5
D6
0
D1
D2
D7
D8
I
ESDpos