ULQ2003A-Q1_15 Datasheet, PDF (12/25 Pages) Texas Instruments – High-Voltage High-Current Darlington Transistor Arrays

ULQ2003A-Q1, ULQ2004A-Q1
SGLS148E – DECEMBER 2002 – REVISED DECEMBER 2015
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9.2.2 Detailed Design Procedure
When using ULQ2003A-Q1 device in a coil driving application, determine the following:
• Input voltage range
• Temperature range
• Output and drive current
• Power dissipation
9.2.2.1 Drive Current
The coil voltage (V_SUP), coil resistance (R_COIL), and low-level output voltage (V_CE(SAT) or V_OL) determine the coil
current.
I_COIL = (V_SUP – V_CE(SAT)) / R_COIL
(1)
9.2.2.2 Low-Level Output Voltage
The low-level output voltage (V_OL) is the same as V_CE(SAT) and can be determined by, Figure 1 or Figure 2.
9.2.2.3 Power Dissipation and Temperature
The number of coils driven is dependent on the coil current and on-chip power dissipation. The number of coils
driven can be determined by Figure 16.
For a more accurate determination of number of coils possible, use Equation 2 to calculate ULQ200xA-Q1 device
on-chip power dissipation P_D:
N
Ã¥ P
D
=
V
OLi
´
I
Li
i=1
where
• N is the number of channels active together
• V_OLi is the OUT_i pin voltage for the load current I_Li. This is the same as V_CE(SAT)
(2)
To ensure reliability of ULQ200xA-Q1 device and the system, the on-chip power dissipation must be lower that or
equal to the maximum allowable power dissipation (PD_(MAX)) dictated by Equation 3.
( ) _{PD(MAX) =} ^T_J(MAX) ^{- T}_{A qJA}
where
• T_J(max) is the target maximum junction temperature
• T_A is the operating ambient temperature
• R_θJA is the package junction to ambient thermal resistance
(3)
Limit the die junction temperature of the ULQ200xA-Q1 device to less than 125°C. The IC junction temperature is
directly proportional to the on-chip power dissipation.
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