Datasheet
DRV102
13
SBVS009B
www.ti.com
low as possible for increased reliability. Junction tempera-
ture can be determined according to the equation:
T
J
= T
A
+ P
D
θ
JA
(1)
where,
θ
JA
=
θ
JC
+
θ
CH
+
θ
HA
(2)
T
J
= Junction Temperature (°C)
T
A
= Ambient Temperature (°C)
P
D
= Power Dissipated (W)
θ
JC
= Junction-to-Case Thermal Resistance (°C/W)
θ
CH
= Case-to-Heat Sink Thermal Resistance (°C/W)
θ
HA
=
Heat Sink-to-Ambient Thermal Resistance (°C/W)
θ
JA
= Junction-to-Air Thermal Resistance (°C/W)
Figure 13 shows maximum power dissipation versus ambi-
ent temperature with and without the use of a heat sink.
Using a heat sink significantly increases the maximum
power dissipation at a given ambient temperature as shown.
FIGURE 12. DDPAK Thermal Resistance versus Circuit Board Copper Area.
THERMAL RESISTANCE vs
CIRCUIT BOARD COPPER AREA
50
40
30
20
10
0
Thermal Resistance, θ
JA
(°C/W)
012345
Copper Area (inches
2
)
DRV102
DDPAK
Surface-Mount Package
1oz. copper
Circuit Board Copper Area
DRV102
DDPAK
Surface-Mount Package
output current times the voltage across the conducting out-
put transistor times the duty cycle. Power dissipation can be
minimized by using the lowest possible duty cycle necessary
to assure the required hold force.
THERMAL PROTECTION
Power dissipated in the DRV102 will cause the junction
temperature to rise. The DRV102 has thermal shutdown
circuitry that protects the device from damage. The thermal
protection circuitry disables the output when the junction
temperature reaches approximately +165°C, allowing the de-
vice to cool. When the junction temperature cools to approxi-
mately +150°C, the output circuitry is again enabled. Depend-
ing on load and signal conditions, the thermal protection
circuit may cycle on and off. This limits the dissipation of the
driver but may have an undesirable effect on the load.
Any tendency to activate the thermal protection circuit
indicates excessive power dissipation or an inadequate heat
sink. For reliable operation, junction temperature should be
limited to +125°C, maximum. To estimate the margin of
safety in a complete design (including heat sink), increase
the ambient temperature until the thermal protection is
triggered. Use worst-case load and signal conditions. For
good reliability, thermal protection should trigger more than
40°C above the maximum expected ambient condition of
your application. This produces a junction temperature of
125°C at the maximum expected ambient condition.
The internal protection circuitry of the DRV102 was designed
to protect against overload conditions. It was not intended to
replace proper heat sinking. Continuously running the
DRV102 into thermal shutdown will degrade reliability.
HEAT SINKING
Most applications will not require a heat sink to assure that
the maximum operating junction temperature (125°C) is not
exceeded. However, junction temperature should be kept as
FIGURE 13. Maximum Power Dissipation versus Ambient
Temperature.
10
8
6
4
2
0
Power Dissipation (Watts)
0 255075100125
Ambient Temperature (°C)
MAXIMUM POWER DISSIPATION
vs AMBIENT TEMPERATURE
TO-220 with Thermalloy
6030B Heat Sink
JA
= 16.5°C/W
P
D
= (T
J
(max) – T
A
)
/
JA
T
J
(max) = 125°C
With infinite heat sink
(
JA
= 3°C/W),
max P
D
= 33W
at T
A
= 25°C
θ
θ
DDPAK
JA
= 26°C/W (3 in
2
1 oz.
copper mounting pad)
θ
DDPAK or TO-220
JA
= 65°C/W (no heat sink)
θ
θ