12
LT1210
1210fa
U
S
A
O
PPLICATI
WU
U
I FOR ATIO
then:
TJ = (0.56W)(46°C/W) + 70°C = 96°C
for the SO package with 1000 sq. mm topside
heat sinking
TJ = (0.56W)(27°C/W) + 70°C = 85°C
for the R package with 1000 sq. mm topside heat
sinking
Since the maximum junction temperature is 150
°C,
both packages are clearly acceptable.
–
+
LT1210
SD
–15V
15V
24k
10k
5V
2N3904
1210 TA04
CMOS Logic to Shutdown Interface
Precision
×10 High Current Amplifier
–
+
LT1097
–
+
LT1210
VIN
SD
COMP
0.01
F
3k
330
9.09k
1k
OUT
OUTPUT OFFSET: < 500
V
SLEW RATE: 2V/
s
BANDWIDTH: 4MHz
STABLE WITH CL < 10nF
1210 TA03
500pF
TYPICAL APPLICATIONS
U
T7 Package, 7-Lead TO-220
Thermal Resistance (Junction-to-Case) = 5
°C/W
Calculating Junction Temperature
The junction temperature can be calculated from the
equation:
TJ = (PD)(θJA) + TA
where:
TJ = Junction Temperature
TA = Ambient Temperature
PD = Device Dissipation
θJA = Thermal Resistance (Junction-to-Ambient)
As an example, calculate the junction temperature for the
circuit in Figure 7 for the SO and R packages assuming a
70
°C ambient temperature.
The device dissipation can be found by measuring the
supply currents, calculating the total dissipation and then
subtracting the dissipation in the load and feedback
network.
PD = (76mA)(10V) – (1.4V)2/ 10 = 0.56W
–
+
LT1210
SD
5V
–5V
680
220
10
0V
2V
VO
VO = 1.4VRMS
76mA
1210 F07
–2V
A
Figure 7