CAT4101TV-T75 CATALYST SEMICONDUCTOR, CAT4101TV-T75 Datasheet - Page 8

• Manufacturer Part Number: CAT4101TV-T75
• Description: IC, LED DRIVER, CONSTANT CURRENT, TO263-5
• Manufacturer: CATALYST SEMICONDUCTOR

Specifications of CAT4101TV-T75

• Led Driver Application: Architectural, Automotive Lighting
• No. Of Outputs: 1
• Output Current: 1A
• Output Voltage: 3.5V
• Input Voltage: 3V To 5.5V
• Topology: Constant Current
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application Information
Single 12 V Supply
LEDs in series from a single 12 V supply using the
CAT4101. The CAT4101 can not be driven directly from
12 V, three components are needed to create a lower voltage
for the VIN pin (below 5.5 V). Resistor R2 and zener diode
D provide a regulated voltage while the quiescent current
runs through the N−Channel transistor M. Suitable parts for
this circuit are the ON Semiconductor MM3Z6V2 zener
diode and the 2N7002L N−channel transistor (SOT23
package).
Power Dissipation
calculated as follows:
where V
high V
the CAT4101 to enter thermal shutdown. In applications
where V
the LED string to lower P
primarily of two paths in series. The first path is the junction
to the case (q
package style, and the second path is the case to ambient
(q
layout. The overall junction to ambient (q
resistance is equal to:
12 V
CA
The circuit shown in Figure 16 shows how to power three
The power dissipation (P
Thermal dissipation of the junction heat consists
) thermal resistance, which is dependent on board
Figure 16. Single Supply Driving Three LEDs
1 mF
LED
C2
LED
LED
voltage or high ambient temperature can cause
P
is the voltage at the LED pin. Combinations of
is high, a resistor can be inserted in series with
JC
D
6.2 V
) thermal resistance which is defined by the
+ (V
5 kW
R2
D
q
IN
JA
0.1 mF
+ q
C1
D
I
IN
.
) ) (V
JC
D
R1
) of the CAT4101 can be
) q
LED
M
CA
VIN
RSET
EN/PWM
CAT4101
I
GND
LED
)
LED
JA
) thermal
http://onsemi.com
8
junction temperature T
dissipation P
following equation:
thermal resistance when the ground tab is soldered down to
the PCB. When mounted on a double−sided printed circuit
board with two square inches of copper allocated for “heat
spreading”, the resulting q
power dissipation is calculated as follow:
Recommended Layout
through the PCB. Multiple via can be used to connect the tab
of the CAT4101 to a large ground plane underneath the
package.
IC as possible. The RSET resistor should have a Kelvin
connection to the GND pin of the CAT4101.
For a given package style and board layout, the operating
The CAT4101 TO−263 5−lead package provides a
For example, at 60°C ambient temperature, the maximum
The board layout should provide good thermal dissipation
Input capacitor C1 should be placed as close to the driver
T
Figure 17. CAT4101 Recommended Layout
P
J
Dmax
+ T
D
AMB
+
, and the ambient temperature, resulting in the
T
) P
Jmax
D
q
* T
(q
JA
JC
J
JA
AMB
is a function of the power
) q
is about 30°C/W.
+ 150 * 60
CA
) + T
30
AMB
) P
+ 3 W
D
q
JA