LT1054_15 Datasheet, PDF (16/33 Pages) Linear Technology – Switched-Capacitor Voltage Converter with Regulator

LT1054
SLVS033G – FEBRUARY 1990 – REVISED JULY 2015
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The resistor reduces the power dissipated by the LT1054 by (4.9 V)(100 mA) = 490 mW. The total power
dissipated by the LT1054 is equal to (940 mW − 490 mW) = 450 mW. The junction-temperature rise is 58°C.
Although commercial devices are functional up to a junction temperature of 125°C, the specifications are tested
to a junction temperature of 100°C. In this example, this means limiting the ambient temperature to 42°C. To
allow higher ambient temperatures, the thermal resistance numbers for the LT1054 packages represent worst-
case numbers, with no heat sinking and still air. Small clip-on heat sinks can be used to lower the thermal
resistance of the LT1054 package. Airflow in some systems helps to lower the thermal resistance. Wide printed
circuit board traces from the LT1054 leads help remove heat from the device. This is especially true for plastic
packages.
8.2.3 Application Curve
2
3.5 V ≤ V_CC ≤ 15 V
1.8 C_i = C_o = 100 μF
1.6
1.4
1.2
1
T_J = 25°C
0.8
0.6
T_J = 125°C
0.4
0.2
T_J = −55°C
0
0 10 20 30 40 50 60 70 80 90 100
Output Current − mA
8.3 System Examples
Figure 17. Voltage Loss vs Output Current
1N4002 ^{100 kΩ}
10 μF ₊
−
+
+
−
1N5817
Tach
Motor
10 V
1
FB/SD
2
CAP+
3
GND
LT1054
V_CC ⁸
7
OSC
6
V_REF
+
5 μF
4
CAP−
V_OUT ⁵
NOTE: Motor-Tach is Canon CKT26-T5-3SAE.
Pin numbers shown are for the P package.
Figure 18. Motor-Speed Servo
100-kΩ
Speed Control
16
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