CAT4106HV4-GT2 Datasheet, PDF (10/17 Pages) ON Semiconductor – 6W Quad Channel DC/DC LED Driver with Diagnostics

CAT4106
BLOCK DIAGRAM
L
V_L
D
R4
R6
R5
R7
SW
VFMAX
VFMIN
C3
LED
Cluster
N_Series
M_Parallel
300mV
OVP
Controller
1A
1MHz PWM
1Ω
Controller
Supply
VIN
EN/DIM
Shutdown
Delay
System
EN/SD
I1
I2
PWM_DIM
200 kΩ
Drive Control
IRSETx100
Ctrl/Fault
Detector
FAULT ^{µC Diagnostics}
CTRL
R2
FB
LED1
LED2
LED3
LED4
I3
I4
0 - 175 mA
R3
RSET
R1
GND
PGND
LEDn
LED1
Figure 4. CAT4106 Simplified Functional Block Diagram
DEVICE OPERATION
In a typical application, the CAT4106 drives an LED
array consisting of up to four separate strings. A
single external resistor value is used to select the
drive level in all output channels. Each channel
provides a very well regulated and tightly matched
bias current on all LED strings.
An integrated DC/DC boost converter is used to
generate the high voltage output required to power the
LED strings. Up to a maximum of 6 W of LED power
can be delivered when powered from a 12 V supply.
To offer improved performance, the device also allows
the user to set the operating voltage level on the
output drive channels. A pair of external resistors is
used to control the nominal channel voltage, during
normal operation. The resulting output voltage (LED
anodes) will be equal to the sum of the adjusted
channel voltage plus the maximum forward voltage
present on any string.
The CAT4106 provides four tightly matched current
sinks to accurately regulate LED current in each
channel. Up to 175 mA per channel can be
programmed by selecting a suitable value for the
external R1 resistor (connected between RSET and
GND pins).
LED CURRENT SETTING
The CAT4106 provides four tightly matched current
sinks to accurately regulate LED current in each
channel. The LED current is set by the external
resistor R1 connected between the feedback pin (FB)
and ground. The following formula gives the
relationship between the resistor value and the LED
current per channel.
R1 ≈ 103 ×
1.2 V
LED current per channel
LED current per channel (mA)
10
20
30
50
100
150
R1 (Ω)
12.4 k
6.19 k
4.12 k
2.49 k
1.24 k
820
Table 1. Resistor R1 and LED current
Doc. No. MD-5037, Rev. A
10
© 2009 SCILLC. All rights reserved.
Characteristics subject to change without notice