Q-Tech QT78 - Manual (Page 5)

5
Q-TECH Corporation - 10150 W. Jefferson Boulevard, Culver City 90232 - Tel: 310-836-7900 - Fax: 310-836-2157 - www.q-tech.com
QT78 SERIES
HIGH RELIABILITY MINIATURE CRYSTAL CLOCK OSCILLATORS
1.8 to 5.0Vdc - 15kHz to 150MHz
Q-TECH
CORPORATION
QT78 (Revision H, January 2011) (ECO #10085)
Vdd
GND
0.1xVdd
0.9xVdd
VOH
VOL
Tr Tf
TH
T
0.5xVdd
SYMMETRY = x 100%
TH
T
Output Waveform (Typical)
Frequency vs. Temperature Curve
Test Circuit
-
-
Output
Ground
4 3
2
0.1µF
15pF
1
Tristate Function
Power
supply 10k
mA
Vdc
+
+
+
(*)
or
0.01µF
QT78
(*) CL includes probe and jig capacitance
Typical test circuit for CMOS logic
Frequency-Temperature Curves QT78RD-70MHz 1.8Vdc
-40
-30
-20
-10
10
20
30
40
-55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35
Temp (ºC)
P
P
M
40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125
0
45º 45º
Hybrid Case
Substrate
Die
D/A epoxy
D/A epoxy
Heat
Die
R1
D/A epoxy Substrate D/A epoxy Hybrid Case
R2 R3 R4 R5
Thermal Characteristics
JA JC CA
Die
T
T
T
C
A
J
CA
JC
(Figure 1)
(Figure 2)
The Tristate function on pin 1 has a built-in pull-up resistor typical 50kΩ, so it can
be left floating or tied to Vdd without deteriorating the electrical performance.
The heat transfer model in a hybrid package is described in
figure 1.
Heat spreading occurs when heat flows into a material layer of
increased cross-sectional area. It is adequate to assume that
spreading occurs at a 45° angle.
The total thermal resistance is calculated by summing the
thermal resistances of each material in the thermal path
between the device and hybrid case.
RT = R1 + R2 + R3 + R4 + R5
The total thermal resistance RT (see figure 2) between the heat
source (die) to the hybrid case is the Theta Junction to Case
(Theta JC) in°C/W.
• Theta junction to case (Theta JC) for this product is 30°C/W.
• Theta case to ambient (Theta CA) for this part is 100°C/W.
• Theta Junction to ambient (Theta JA) is 130°C/W.
Maximum power dissipation PD for this package at 25°C is:
• PD(max) = (TJ (max) – TA)/Theta JA
• With TJ = 175°C (Maximum junction temperature of die)
• PD(max) = (175 – 25)/130 = 1.15W