August 2007 Rev 2 1/11
11
BU508AF
High voltage NPN power transistor for standard
definition CRT display
Features
■State-of-the-art technology:
– Diffused collector “Enhanced generation”
■Stable performances versus operating
temperature variation
■Low base-drive requirement
■Tight hFE range at operating collector current
■High ruggedness
■Fully insulated power package U.L. compliant
Applications
■Horizontal deflection output for CRT TV
■Switch mode power supplies for CRT TV
Description
The BU508AF is manufactured using diffused
collector in planar technology adopting new and
enhanced high voltage structure for updated
performance to the horizontal deflection stage.
Figure 1. Internal schematic diagram
ISOWATT218FX
123
Table 1. Device summary
Order code Marking Package Packaging
BU508AF BU508AF ISOWATT218FX Tube
www.st.com
Content BU508AF
2/11
Content
1 Electrical ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Electrical characteristics (curves) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Test circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
BU508AF Electrical ratings
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1 Electrical ratings
Table 2. Absolute maximum rating
Symbol Parameter Value Unit
VCES Collector-emitter voltage (VBE = 0) 1500 V
VCEO Collector-emitter voltage (IB = 0) 700 V
VEBO Collector-base voltage (IC = 0) 9 V
ICCollector current 8 A
ICM Collector peak current (tP < 5ms) 15 A
IBBase current 4 A
PTOT Total dissipation at Tc = 25°C 50 W
Vins
Insulation withstand voltage (RMS) from all three leads to
external heatsink 2500 V
Tstg Storage temperature -65 to 150
°C
TJMax. operating junction temperature 150
Table 3. Thermal data
Symbol Parameter Value Unit
Rthj-case Thermal resistance junction-case _______________max 2.5 °C/W
Electrical characteristics BU508AF
4/11
2 Electrical characteristics
(Tcase = 25°C unless otherwise specified)
Table 4. Electrical characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
ICES
Collector cut-off current
(VBE =0)
VCE = 1500V
VCE = 1500V; TC= 125°C
0.2
2
mA
mA
IEBO
Emitter cut-off current
(IC =0) VEB = 9V 1mA
VCEO(sus) (1)
Collector-emitter
sustaining voltage
(IC =0)
IC = 100mA 700 V
VCE(sat) (1)
1. Pulsed: Pulse duration = 300 ms, duty cycle 1.5 %
Collector-emitter
saturation voltage IC = 4.5A IB = 1.6A 1V
VBE(sat) (1) Base-emitter saturation
voltage IC = 4.5A IB = 2A 1.1 V
hFE (1) DC current gain IC = 0.1A VCE = 5V
IC = 4.5A VCE = 5V
10
5
30
ts
tf
Inductive load
Storage time
Fall time
IC = 4.5A IB(on) = 0.5A
VBE(off) = -2.7V fh = 16KHz
LBB(off) = 4.5µH
2.5
0.2
µs
µs
BU508AF Electrical characteristics
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2.1 Electrical characteristics (curves)
Figure 2. Safe operating area Figure 3. Derating curve
Figure 4. DC current gain Figure 5. DC current gain
Figure 6. Collector-emitter saturation
voltage
Figure 7. Base-emitter saturation
voltage
Electrical characteristics BU508AF
6/11
Figure 8. Output characteristics
BU508AF Electrical characteristics
7/11
2.2 Test circuits
Figure 9. Power losses and inductive load switching
Figure 10. Reverse biased safe operating area
Package mechanical data BU508AF
8/11
3 Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a Lead-free second level interconnect. The category of
second level interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com
BU508AF Package mechanical data
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Dim. mm.
Min. Typ Max.
A5.305.70
C2.803.20
D3.10 3.50
D1 1.802.20
E0.801.10
F0.65 0.95
F2 1.802.20
G10.30 11.50
G1 5.45
H15.30 15.70
L910.20
L2 22.8023.20
L326.30 26.70
L4 43.20 44.40
L5 4.304.70
L6 24.30 24.70
L7 14.60 15
N1.802.20
R3.804.20
Dia3.40 3.80
ISOWATT218FX mechanical data
7627132 B
BU508AF
11/11
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