AD745KR-16-REEL7 Analog Devices Inc, AD745KR-16-REEL7 Datasheet - Page 9

• Manufacturer Part Number: AD745KR-16-REEL7
• Description: IC OPAMP BIFET 20MHZ ULN 16SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD745KR-16-REEL7

• Rohs Status: RoHS non-compliant
• Amplifier Type: J-FET
• Number Of Circuits: 1
• Slew Rate: 12.5 V/µs
• Gain Bandwidth Product: 20MHz
• -3db Bandwidth: 20MHz
• Current - Input Bias: 150pA
• Voltage - Input Offset: 100µV
• Current - Supply: 8mA
• Current - Output / Channel: 40mA
• Voltage - Supply, Single/dual (±): 9.6 V ~ 36 V, ±4.8 V ~ 18 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.300", 7.5mm Width)
• Output Type: -

HOW CHIP PACKAGE TYPE AND POWER DISSIPATION
AFFECT INPUT BIAS CURRENT
As with all JFET input amplifiers, the input bias current of the
AD745 is a direct function of device junction temperature, I
approximately doubling every 10°C. Figure 9 shows the rela-
tionship between bias current and junction temperature for the
AD745. This graph shows that lowering the junction tempera-
ture will dramatically improve I
The dc thermal properties of an IC can be closely approximated
by using the simple model of Figure 10 where current represents
power dissipation, voltage represents temperature, and resistors
represent thermal resistance (θ in °C/watt).
From this model T
mined in a particular application by using Figure 9 together with
the published data for θ
modify θ
Aavid #5801. Figure 11 shows bias current versus supply voltage
with θ
bias current after θ
double for every 10°C.
JA
10
10
10
10
10
10
10
as the third variable. This graph can be used to predict
–10
–11
–12
JA
–6
–7
–8
–9
–60
by use of an appropriate clip-on heat sink such as the
V
T
WHERE:
P
T
T
A
S
JC
CA
IN
A
J
–40
= 15V
= 25 C
= JUNCTION TEMPERATURE
= AMBIENT TEMPERATURE
= DEVICE DISSIPATION
= THERMAL RESISTANCE – JUNCTION TO CASE
= THERMAL RESISTANCE – CASE TO AMBIENT
JA
J
–20
P
= T
IN
has been computed. Again bias current will
T
J
JUNCTION TEMPERATURE – C
JA
A
0
+θ
and power dissipation. The user can
JA
JC
20
P
JA
B
IN
.
. Therefore, I
40
60
CA
80
T
A
B
100
can be deter-
120
140
B
REDUCED POWER SUPPLY OPERATION FOR
LOWER I
Reduced power supply operation lowers I
lowering both the total power dissipation and, second, by reduc-
ing the basic gate-to-junction leakage (Figure 11). Figure 13
shows a 40 dB gain piezoelectric transducer amplifier, which
operates without an ac coupling capacitor, over the –40°C to
+85°C temperature range. If the optional coupling capacitor,
C1, is used, this circuit will operate over the entire –55°C to
+125°C temperature range.
300
200
100
0
B
5
T
A
T
A
= 25 C
C1
TRANSDUCER
CASE
OPTIONAL DC BLOCKING CAPACITOR
OPTIONAL, SEE TEXT
θ
C
T
10
8
100
SUPPLY VOLTAGE –
10
8
10k
T
CT
J
10
AD745
A
(DIE MOUNT
TO CASE)
+
+5V
–5V
B
(J TO DIE
MOUNT)
Volts
A
B
B
=
JA
JA
in two ways: first, by
JA
JC
= 165 C/W
= 115 C/W
= 0 C/W
AD745
15