Transcript OPA564 EOS Analysis

OPA564 EOS Analysis
TI CONFIDENTIAL – NDA RESTRICTIONS
1
This is your IC
This is your IC after an EOS event!
ESD and EOS: What’s the difference?
• Electrostatic Discharge (ESD) – The transfer of electrostatic charge
between bodies or surfaces at different electrostatic potential.
• Electrical Over Stress (EOS) – The exposure of an item to current or
voltage beyond its maximum ratings.
ESD
High voltage (kV’s)
Short duration event (1-100ns)
Fast edges
Low power
Out of circuit event
EOS
Low voltage >Vs
Longer duration event
Low power
In-circuit event
Two very different environments
Handling and assembly
environments
ESD
PC Board
EOS
-5V bus
V1 5
L1 50n
C1 100n
R2 10k
R1 1k
OP2 !OPAMP
OP1 !OPAMP
-
-
Vout
10V
+
+
0V
+
C2 100n
+
+
VG1
R4 1k
R3 1k
L2 50n
+5V bus
V2 5
ESD Stress Models
C1 100p
L1 7.5u
+
R1 1.5k
VG1
ESD model
R
L
C
V
Human Body Model
HBM
1.5 kΩ
7500 nH
100 pF
≥ 2kV
Machine Model
MM
20 Ω
750 nH
200 pF
100 - 200V
Charged Device Model
CDM
20 Ω
5 nH
2-10pF
200V - 1kV
Human Body model
ESD Human Body Model
modeled in TINA
DUT
IC1
2kV
IC
SW1 L1 7.5u
R1 1.5k
VF1
t
Rdut 10
C2 2p
C1 100p
1.5
T
+
A
AM1
1.0
AM1 (Amps)
500.0m
Rdut is “on”
resistance of an ESD
protection circuit
Rdut = 10 Ohms
0.0
15.0
10.0
VF1 (Volts)
5.0
0.0
0
50n
100n
Time (s)
150n
200n
Machine Model
ESD Machine Model
modeled in TINA
DUT
IC1
200V
IC
SW1 L1 500n
R1 10
VF1
t
Rdut 10
C2 2p
C1 200p
+
4.0
T
A
Rdut = 10 Ohms
AM1
2.0
AM1 (Amps)
0.0
Rdut is “on”
resistance of an ESD
protection circuit
-2.0
40.0
20.0
VF1 (Volts)
0.0
-20.0
0
50n
100n
Time (s)
150n
200n
CDM - ESD by induction
T 400
Cp: 2p[F]
Cp: 4p[F]
Cp: 6p[F]
Voltage (V)
200
0
VG1
Charge Device Model
modeled in TINA
-200
DUT
L1 5n
0.0
R1 20
VF1
1.0n
2.0n
Time (s)
3.0n
4.0n
2.0n
Time (s)
3.0n
4.0n
T 5.0
Cp: 6p[F]
250V
Cp: 4p[F]
+
Rdut 10
VG1
Cp: 2p[F]
Cp 2p
Current (A)
2.5
0.0
+
A
AM1
-2.5
-5.0
0.0
1.0n
Typical Failure Result from Transient
Spike
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Root Cause for the Failures
• The output ESD cell is damaged
• The output ESD cell can only be damaged by 2 methods:
– Overvoltage to the V+ power supply pin
– Overvoltage (or overcurrent) to the Vout pin
• In either condition it is assumed the OPA564 is under power during the
overvoltage condition and the output is disabled (this is worst case
scenario)
The absolute maximum ratings of the OPA564 are being exceeded due to
transient pulses at the output
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Overvoltage to V+ Supply Pin
T
500m
400m
+
A
300m
Current (A)
+
+
OPA564
200m
Damage will Occur beyond 41V
100m
OPA564 Absolute Maximum is specified at 26V
0
-100m
0
5
10
15
20
25
30
35
40
45
VSupply (V)
In the diagram above it is illustrated that if the power supply voltage raises beyond
~41V damage will occur to the output ESD cell
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Inside the OPA564…
VDD
+
+
OUT
-
Pow er Supply
VDD
+
+
OUT
-
Pow er Supply
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Overvoltage / Overcurrent to Vout Pin
T
500m
400m
12V
+
200m
+
+
A
-
+
Current (A)
300m
Damage to the output ESD cell
will occur after 80mA or around 12.9V
Vsource
OPA564
When using a 12V power supply
the absolute maximum for the OPA564
output pin is given as 12.4V
100m
VSupply = 12V
0
-100m
0
3
6
9
12
15
VSource (V)
In the diagram below it is illustrated that if the output voltage raises above the
power supply such that >80mA flows into the output ESD cell damage will occur to
the output ESD cell
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Inside the OPA564…
OUT
Current Pulse
VDD
+
+
-
Pow er Supply
OUT
Current Pulse
VDD
+
+
-
Pow er Supply
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OPA564 Absolute Maximum Ratings
The Absolute Maximum Ratings of the most relevance are highlighted above
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Comparison of Diode Specifications
Device
Imax (A)
VF @ rated current (V)
Rated Current (A)
Cj (pF)
BAS70
0.1 (too low)
1 (too high)
0.015 (too low)
2
STPS1L40A
60
0.63
2
60
B350A
80
0.7
3
200
T
100
B350A
10
0.4V Forward Diode Voltage Equates to
Absolute Max Condition on OPA564
Damage will occur
if the current in the
B350A exceeds ~ 25A
STPS1L40A
Damage will occur
if the current in the
STPS1L40A exceeds ~ 6A
Output
1
100m
BAS70
10m
Damage will occur
if the current in the BAS70
exceeds ~20mA
1m
0.00
1.00
Input voltage (V)
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