AS1105WL-T austriamicrosystems, AS1105WL-T Datasheet - Page 12

• Manufacturer Part Number: AS1105WL-T
• Description: IC DRIVER LED 4-DIGIT 20-SOIC
• Manufacturer: austriamicrosystems

Specifications of AS1105WL-T

• Display Type: LED
• Configuration: 7 Segment + DP
• Interface: Serial
• Digits Or Characters: 4 Digits
• Current - Supply: 330mA
• Voltage - Supply: 4 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-SOIC (0.300", 7.50mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AS1105
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Cascading Drivers
The AS1105 can be cascaded as well. The DOUT pin must be connected to the DIN pin of the following AS1105.
Table 16. Package Thermal Resistance Data
Computing Power Dissipation
The upper limit for power dissipation (PD) for the AS1105 is determined from the following equation:
Where:
V
DUTY = duty cycle set by intensity register
N = number of segments driven (worst case is 4)
V
I
Dissipation Example:
I
PD = 5.25V(0.5mA) + (5.25V - 1.8V)(31/32 x 40mA x 4) = 0.54W
Thus, for a SO package θJA = +85ºC/W (see Table 13), the maximum allowed ambient temperature T
Where: T
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SEG
SEG
DD
LED
= supply voltage
= segment current set by R
= 40mA, N = 4, DUTY = 31/32, V
= LED forward voltage
A
= +104ºC
20 Wide SO
Package
PD = (V
T
J,MAX
SET
Maximum Junction Temperature (TJ) = +150°C
= T
Maximum Ambient Temperature (TA) = +85°C
DD
LED
A
x 0.5mA) + (V
+ PD x
= 1.8V at 40mA, V
θ
JA = 150ºC = T
Revision 1.34
DD
- V
LED
DD
)(DUTY x I
= 5.25V
A
+0.54W x 85ºC/W
Thermal Resistance (θ
SEG
x N)
+85°C/W
JA
)
A
is given by:
12 - 15
(EQ 1)
(EQ 2)