LTC5576
18
5576fa
For more information www.linear.com/LTC5576
Figure 11. TEMP Pin Voltage vs Junction Temperature
applicaTions inForMaTion
Table 4. Recommended R1 Values
V
CC
(V) f
IN
(MHz) f
OUT
(MHz) f
LO
(MHz) R1 (Ω)
3.3 456 3500 3044 511
3.3 900 5800 4900 649
3.3 900 8000 7100 649
5.0 456 3500 3044 2.61k
5.0 900 5800 4900 2.61k
5.0 1300 5000 6300 2.61K
Temperature Monitor Pin (TEMP)
The TEMP pin (pin 1) is connected to an on-chip diode that
can be used as a coarse temperature monitor by forcing
current into it and measuring the resulting voltage. The
temperature diode is protected by a series 30Ω resistor and
additional ESD diodes to ground. The TEMP pin voltage is
shown as a function of junction temperature in Figure 11.
Given the voltage at the pin, V
TEMP
, (in mV) the junction
temperature in °C can be estimated for forced input cur-
rents of 10µA and 80µA using the following equations:
T
J
(10µA) = (742.4 – V
TEMP
)/1.796
T
J
(80µA) = (795.6 – V
TEMP
)/1.609
Supply Voltage Ramping
Fast ramping of the supply voltage can cause a current
glitch in the internal ESD protection circuits. Depending on
the supply inductance, this could result in a supply volt
-
age transient that exceeds the maximum rating. A supply
voltage ramp time of greater than
1ms
is recommended.
It is recommended that the EN pin be used to enable or
disable the LTC5576 with V
CC
held constant. However,
if the EN pin and V
CC
are switched simultaneously, then
the configuration shown in Figure 12 is recommended.
A maximum V
CC
ramp rate at pins 6 and 7 of 20V/ms is
recommended.
JUNCTION TEMPERATURE (°C)
–50
TEMP PIN VOLTAGE (mV)
800
850
750
700
650
600
9070503010–10–30 110
550
500
900
5576 F11
I
IN
= 80µA
I
IN
= 10µA
Figure 12. Suggested Configuration for Simultaneous V
CC
and EN Switching
Auto Supply Voltage Detection
An internal circuit automatically detects the supply volt-
age and configures internal components for 3.3V or 5V
operation. The DC current is affected when the auto-detect
circuit switches at approximately 4.1V. To avoid undesired
operation, the mixer should only be operated in the 3.1V
to 3.5V or 4.5V to 5.3V supply ranges.
Spurious Output Levels
Mixer spurious output levels vs harmonics of the IN and
LO frequencies are tabulated in Tables 5 and 6 for the 5V,
5800MHz application. Results are shown for spur frequen
-
cies up to 18GHz. The spur frequencies can be calculated
using the following equation:
f
SPUR
= |M • f
IN
± N • f
LO
|
Table 5 lists the difference spurs (f
SPUR
= |M • f
IN
– N •
f
LO
|) and Table 6 lists the sum spurs (f
SPUR
= |M • f
IN
+
N • f
LO
|). The spur levels were measured on a standard
evaluation board at room temperature using the test circuit
of Figure 1.
The spurious output levels for any application will be de
-
pendent on the external matching circuits and the particular
application frequencies.
LTC5576
5 6 7
220µF
0.5Ω
10k
V
CC
V
CC
V
CC
EN
