Texas Instruments LM4570 Evaluation Board LM4570LQBD/NOPB LM4570LQBD/NOPB Fiche De Données
Codes de produits
LM4570LQBD/NOPB
0
50
100
150
200
250
PO
W
ER
D
ISSI
PAT
IO
N
(
mW
)
0
1
2
3
4
5
INPUT VOLTAGE (V)
V
DD
= 5V
SNOSAV2C – APRIL 2006 – REVISED APRIL 2013
Figure 20. Power Dissipation vs. Input Voltage
EXPOSED-DAP MOUNTING CONSIDERATIONS
The LM4570 is available in an 8-pin WSON package which features an exposed DAP (die attach paddle). The
exposed DAP provides a direct thermal conduction path between the die and the PCB, improving the thermal
performance by reducing the thermal resistance of the package. Connect the exposed DAP to GND through a
large pad beneath the device, and multiple vias to a large unbroken GND plane. For best thermal performance,
connect the DAP pad to a GND plane on an outside layer of the PCB. Connecting the DAP to a plane on an
inner layer will result in a higher thermal resistance. Ensure efficient thermal conductivity by plugging and tenting
the vias with plating and solder mask, respectively.
exposed DAP provides a direct thermal conduction path between the die and the PCB, improving the thermal
performance by reducing the thermal resistance of the package. Connect the exposed DAP to GND through a
large pad beneath the device, and multiple vias to a large unbroken GND plane. For best thermal performance,
connect the DAP pad to a GND plane on an outside layer of the PCB. Connecting the DAP to a plane on an
inner layer will result in a higher thermal resistance. Ensure efficient thermal conductivity by plugging and tenting
the vias with plating and solder mask, respectively.
POWER SUPPLY BYPASSING
Good power supply bypassing is critical for proper operation. Locate both the REF1 and V
DD
bypass capacitors
as close to the device as possible. Typical applications employ a regulator with a 10µF tantalum or electrolytic
capacitor and a ceramic bypass capacitor which aid in supply stability. This does not eliminate the need for
bypass capacitors near the LM4570. Place a 1µF ceramic capacitor as close to V
capacitor and a ceramic bypass capacitor which aid in supply stability. This does not eliminate the need for
bypass capacitors near the LM4570. Place a 1µF ceramic capacitor as close to V
DD
as possible. Place a 0.1µF
capacitor as close to REF1 as possible. Smaller values of C
REF1
may be chosen for decreased turn on times.
SHUTDOWN FUNCTION
The LM4570 features a low power shutdown mode that disables the device and reduces quiescent current
consumption to 0.1µA. Driving /SD Low disables the amplifiers and bias circuitry, and drives V
consumption to 0.1µA. Driving /SD Low disables the amplifiers and bias circuitry, and drives V
REF1
and the
outputs to GND. Connect /SD to V
DD
for normal operation.
8
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