AN1474: High Temperature Behavior of ISL3158AE

High Temperature Behavior of ISL3158AE
®
Application Note
Description
July 7, 2009
AN1474.0
At a Data Rate of 10Mbps:
The ISL3158AE is a 5V based RS-485 MIL temp rated
transceiver aimed at addressing applications that require
high operating temperatures. The receiver inputs A and B
are presented in pins 6 and 7; when RE# is low this
differential input signal is processed and available at the RO
pin. The Driver input is presented at pin 4 and the driver
differential outputs Z and Y are available at pins 6 and 7
respectively when DE is high. This Application Note aims at
characterizing the device at temperatures of +125°C through
+200°C.
Device Pinout
ISL3158AE
(8 LD SOIC)
TOP VIEW
RO 1
8
VCC
RE 2
7
B/Z
DE 3
6
A/Y
5
GND
DI 4
R
D
2. First pulse missing Threshold at a die temperature range
of min. = +175°C and a max of +191°C
At a Data Rate of 400kbps:
1. Pulse width 90% threshold at a die temp of min. = +190°C
and max = +196°C while operating at a data rate of
10Mbps
As can be seen, operation at a data rate of 10Mbps limits the
device operation to +160°C or less and a data rate of
400kbps allows the device to operate at a temperature of
about +190°C. See “Typical Performance Curves” on
page 3.
This is based on a sample size of 15pcs. and a six sigma
distribution.
TX High Temperature Test
Figure 1 shows the evaluation board schematic. The device
evaluation board is common to both TX and RX. The mode
of operation is determined by the logic presented to the DE
and RE# pins.
The TX was tested using a the EVALB TX portion of
Figure 2. The 200ft cable was disconnected and
terminations of 100Ω and 54Ω were connected based on
test requirement. The parameters tested were: Driver
differential output voltage, propagation delay, and skew. The
results are per the “Typical Performance Curves” on page 3.
Supply Current vs High Temperature
RX High Temperature Test
Figure 2 shows the High temperature test setup. The board
wired up as the transmitter is called the EVALB TX and the
one wired the receiver is called the EVALB RX. The
differential lines were hooked up through 200ft of twisted pair
cable terminated on either side by 120Ω. The VIN was set to
a worst case of 4.5V. The driver input of the EVALB TX is
connected to a function generator capable of providing fast
rise and fall times. The function generator output was set to
provide a burst mode of five pulses at a bit rate of
10Mbps.The RX device was wired up with two
thermocouples one placed on the device case top and the
the other placed on the PWB near the GND pin. The RX
device was heated using a temperature forcing system from
+25°C to +200°C. The Rx shows two threshold points as
follows:
1
1. Pulse width 70% threshold at a die temperature of
min. = +160°C and max. = +175°C while operating at a
data rate of 10Mbps
The supply current is found to have a knee at around +195°C,
and increases rapidly thereafter.The supply current with (driver
enabled) DE high is typically around 650µA. This value
increases to about 1085µA at +240°C. With DE connected to
GND (driver disabled) the supply current drops to about 450µA
typical. This value of supply current increases from a
temperature of +200°C and higher to about 704.5µA.
Driver input vs High Temperature
The Driver input is found to latch to a 5V state at around
+215°C. This causes the drive signal to ride on a 5V DC.
The driver output is non-existent. Some device failures were
observed when left in this state for prolonged period of time.
See Figures 1 and 2.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Application Note 1474
VCC/3.3V/PIN8
C6
10u
TP3/RO/PIN1
0
U1
TP4/RE#/PIN2
1
2
3
4
TP5/DE/PIN3
TP6/DI/PIN4
RO
RE
DE
DI
C2B
0.1u
VCC
TX-Z / RX-B
TX-Y / RX-A
GND
8
7
6
5
0
TP8/TX-Z/RX-B/PIN7
R10
120
TP7/TX-Y/RX-A/PIN6
ISL3178
GND/PIN5
R5
49.9
0
R6
49.9
0
R7
49.9
0
FIGURE 1. EVALUATION BOARD SCHEMATIC
SCOPE1/CH3
SCOPE1/CH1
SCOPE1/CH4
SCOPE1/CH2
CABLE 200ft
V2
4.5V
V3
TP4/RE#/PIN2
TP5/DE/PIN3
VCC/3.3V/PIN8
0
4.5V
RX
0
TP4/RE#/PIN2
TP8/TX-Z/RX-B/PIN7
TP5/DE/PIN3
VCC/3.3V/PIN8
TX
TP7/TX-Y/RX-A/PIN6
TP6/DI/PIN4
EVALB
V1 = 0
V2 = 3
TD = 0
TR = 1ns
TF = 1ns
PW = 100ns
PER = 200ns
TP3/RO/PIN1
SCOPE1/CHx
GND/PIN5
TP3/RO/PIN1
TP7/TX-Y/RX-A/PIN6
GND/PIN5
TP6/DI/PIN4
TP8/TX-Z/RX-B/PIN7
EVALB
V1
0
0
0
SCOPE1/CHx
FIGURE 2. HIGH TEMPERATURE TEST SETUP
2
AN1474.0
July 7, 2009
Application Note 1474
Typical Performance Curves
3.9
3.7
RDIFF = 100Ω
3.5
3.3
3.1
RDIFF = 54Ω
2.9
2.7
-55
0
55
110
TEMPERATURE (°C)
2.5
220
165
DIFFERENTIAL OUTPUT VOLTAGE (V)
FIGURE 4. DRIVER INPUT LATCHED TO 5V at +215°C TYP
FIGURE 3. DRIVER INPUT NORMAL AT +25°C
FIGURE 6. DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs
TEMPERATURE
FIGURE 5. RO OUTPUT PW IS 70% AT +170.5°C TYP
1200
12
1100
1000
900
8
800
6
ICC DE-VCC
700
4
ICC (µA)
DATA RATE IN Mbps
10
600
500
2
400
ICC DE-GND
0
155
160
165
170
175
180
TEMPERATURE (°C)
185
190
FIGURE 7. DATA RATE vs TEMPERATURE
3
195
-100
-50
0
50
100
150
200
TEMPERATURE (°C)
250
300
300
FIGURE 8. SUPPLY CURRENT vs TEMPERATURE
AN1474.0
July 7, 2009
Application Note 1474
Typical Performance Curves (Continued)
1.0
31
tPHL
25
tPLH
23
21
19
-100
-50
0
50
100
150
TEMPERATURE (°C)
200
17
250
FIGURE 9. DRIVER DIFFERENTIAL PROPAGATION DELAY
vs TEMPERATURE
FIGURE 11. PULSE MISSING AT +185°C TYP AND 10Mbps
0.8
0.7
0.6
0.5
0.4
SKEW (ns)
27
0.9
PROPOGATION DELAY (ns)
29
0.3
SKEW
0.2
0.1
-100
-50
0
50
100
150
TEMPERATURE (°C)
200
0
250
FIGURE 10. DRIVER DIFFERENTIAL SKEW vs
TEMPERATURE
FIGURE 12. TX/RX WAVEFORM AT +194°C TYP AND 400kbps
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verify that the Application Note or Technical Brief is current before proceeding.
For information regarding Intersil Corporation and its products, see www.intersil.com
4
AN1474.0
July 7, 2009
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