TC648
VDD
VDD
VDD
Fan
Fan
Fan
RBASE
RBASE
VOUT
Q1
VOUT
Q1
VOUT
Q1
Q2
GND
a) Single Bipolar Transistor
GND
b) Darlington Transistor Pair
GND
C) N-Channel MOSFET
FIGURE 5-6:
Output Drive Transistor Circuit Topologies.
TABLE 5-1: TRANSISTORS AND MOSFETS FOR Q1 (VDD = 5V)
Device
Package
Max. VBE(sat)/VGS
(V)
Min. HFE
VCEO/VDS
(V)
Fan Current
(mA)
Suggested
RBASE (Ω)
MMBT2222A
SOT-23
1.2
50
40
150
800
MPS2222A
TO-92
1.2
50
40
150
800
MPS6602
TO-92
1.2
50
40
500
301
SI2302
SOT-23
2.5
NA
20
500
Note 1
MGSF1N02E
SOT-23
2.5
NA
20
500
Note 1
SI4410
SO-8
4.5
NA
30
1000
Note 1
SI2308
SOT-23
4.5
NA
60
500
Note 1
Note 1: A series gate resistor may be used in order to control the MOSFET turn-on and turn-off times.
2002 Microchip Technology Inc.
DS21448C-page 13