ATA6620 Datasheet, PDF (10/19 Pages) ATMEL Corporation – LIN ABUS TRANSCEIVER WITH INTEGRATED VOLTAGE REGULATOR

6. Voltage Regulator
The voltage regulator needs an external capacitor for compensation and to smooth the distur-
bances from the microcontroller. It is recommend to use an electrolytic capacitor with C > 1.8 µF
and a tantalum capacitor with C = 100 nF. The values of these capacitors can be varied by the
customer, depending on the application.
During mode change from Silent to Normal mode, the voltage regulator ramps up to 6V for only
a few microseconds before it drops back to 5V. This behavior depends on the value of the load
capacitor. With 4.7 µF, the overshoot voltage has its greatest value. This voltage decreases with
higher or lower load capacitors.
With this special SO8 package (fused lead frame to pin3) an R_thja of 100 K/W is achieved.
Therefore it is recommended to connect pin 3 with a wide GND plate on the printed board to get
a good heat sink.
The main power dissipation of the IC is created from the V_CC output current I_VCC, which is
needed for the application.
Figure 6-1 shows the safe operating area of the ATA6620.
Figure 6-1. Save Operating Area versus V_CC Output Current and Supply Voltage V_S at Differ-
ent Ambient Temperatures
60.00
50.00
I_OUT, T_amb = 85°C
40.00
30.00
20.00
10.00
I_OUT, T_amb = 105°C
I_OUT, T_amb = 95°C
0.00
5 6 7 8 9 10 11 12 13 14 15 16 17 18
V_S /V
10 ATA6620 [Preliminary]
4850A–AUTO–02/05