DRV590_16 Datasheet, PDF (12/18 Pages) Texas Instruments – 1.2-A HIGH-EFFICIENCY PWM POWER DRIVER

DRV590
SLOS365A – AUGUST 2001 – REVISED AUGUST 2002
APPLICATION INFORMATION
general operation (continued)
input configuration—differential and single-ended
If a differential input is used, it should be biased around the mid-rail of the DRV590 and must not exceed the
common-mode input range of the input stage (see the operating characteristics at the beginning of the data
sheet).
The most common configuration employs a single-ended input. The unused input should be tied to the mid-rail,
which may be simply accomplished with a resistive voltage divider. For the best performance, the resistor values
chosen should be at least an order of magnitude lower than the input resistance of the DRV590 at the selected
gain setting. This prevents the bias voltage at the unused input from shifting when the signal input is applied.
A small ceramic capacitor should also be placed from the input to ground to filter noise and keep the voltage
stable.
power supply decoupling
To reduce the effects of high-frequency transients or spikes, a small ceramic capacitor, typically 0.1 µF to 1 µF,
should be placed as close to each PVDD pin of the DRV590 as possible. For bulk decoupling, a 10-µF to 100-µF
tantalum or aluminum electrolytic capacitor should be placed relatively close to the DRV590.
SHUTDOWN operation
The DRV590 includes a shutdown mode that disables the outputs and places the device in a low supply current
state. The SHUTDOWN pin may be controlled with a TTL logic signal. When SHUTDOWN is held high, the
device operates normally. When SHUTDOWN is held low, the device is placed in shutdown. The SHUTDOWN
pin must not be left floating. If the shutdown feature is unused, the pin may simply be connected to V_DD.
power dissipation and maximum ambient temperature
Though the DRV590 is much more efficient than traditional linear solutions, the IR drop across the on-resistance
of the output transistors generates some heat in the package, which may be calculated using equation 8.
ǒ Ǔ²
PDISS + IOUT
rds(on), _total
(8)
For example, at the maximum output current of 1.2 A through a total on-resistance of 1 Ω, the power dissipated
in the package is 1.44 W.
The maximum ambient temperature can be calculated using equation 9.
TA + TJ^ǒq_JA PDISS^Ǔ
(9)
Continuing the example above, the maximum ambient temperature driving 1.2 A without exceeding 89°C
junction temperature for a DRV590 in the DWP package (see the maximum output current vs duty cycle section)
is 39°C.
maximum output current vs duty cycle
At 100% duty cycle across the load, the reliability of the DRV590 is degraded if more than 1 A is driven through
the outputs. Furthermore, the junction temperature must not exceed 89°C at the maximum output current levels
to prevent further degradation. However, as the duty cycle across the load decreases, the maximum allowable
output current increases.
Table 2 shows the typical maximum output current, voltage across the load, and junction temperature versus
duty cycle. The dissipation and junction temperatures were calculated using equations 8 and 9. The total
on-resistance was assumed to be 1 Ω, the ambient temperature to be 25°C, and the θ_JA to be 34.1°C/W.
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