CAT4106YP-T2 ON Semiconductor, CAT4106YP-T2 Datasheet - Page 11

• Manufacturer Part Number: CAT4106YP-T2
• Description: LED Drivers LED DRVR BOOST 4CH/10LED
• Manufacturer: ON Semiconductor

Specifications of CAT4106YP-T2

• Number Of Digits: 4
• Low Level Output Current: 10 mA
• High Level Output Current: 175 mA
• Operating Supply Voltage: - 0.3 V to 6 V
• Maximum Supply Current: 4.4 mA
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: TSSOP-16
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

level of 18 V is calculated as follows:
For R7 = 20 kW, R6 = 280 kW.
Setting VFMAX Level (Open−LED)
for the LED string voltage “window of operation”. This
voltage setting is based on the number of series LEDs being
used and the expected maximum V
Example: Consider a string of 6 LEDs in series, with each
LED having a V
maximum V
expected string voltage would be 24 V. Any string voltage
which appears greater than 24 V would be considered as
containing an open−circuit in one or more of the series
LEDs. The external resistor R4 value needed to set a
VFMAX level of 24 V is calculated as follows:
For R5 = 20 kW, R4 = 380 kW.
V
largest string voltage tries to exceed VFMAX setting, it will
no longer be allowed to control the voltage level of
VCTRL/VFB (i.e. it will be ignored) and subsequently the
next largest LED string voltage will then be used in the
control loop. All remaining functional LED channels will
continue to operate as normal. If a disconnected LED string
is reconnected, the FAULT flag remains on and the channel
disabled until the device has been re−enabled with the EN
pin going from low to high.
then the boost converter will limit the output voltage to the
VFMAX setting. This eliminates the need for an external
protection zener.
Enable and PWM Dimming Control
functions. The first function is to enable and disable the
entire device. The second function is to apply PWM
dimming on the output channels while the chip remains fully
enabled. Applying logic high on the EN/PWM input will
power up the device. The device will continue to remain
powered up, even in the presence of PWM signals being
applied. To disable the device into complete system
shutdown mode, a logic low must be applied to the
EN/PWM input for typically 5 ms.
to all the output channels. Each time the input is taken low,
all output channels will immediately be switched off and the
channels will resume normal operation when the PWM is
taken back high. The response time of the channels when
switching ON or OFF is typically 0.2 ms.
F
The external resistor R6 value needed to set a VFMIN
The VFMAX level represents the maximum level expected
In normal operation, the LED string which has the largest
If all LED channels are detected as being open−circuit,
EN/PWM input signal provides two independent
The duty cycle applied at the EN/PWM is directly applied
will be used to set the VCTRL/VFB voltage levels. If the
F
of each LED is 4.0 V, the overall maximum
R6 + R7
R4 + R5
F
range of 3.5 V ± 0.5 V. Since the
1.2 V
1.2 V
18 V
24 V
F
during normal operation.
* 1
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pulse width interval (either High or Low) is 0.2 ms. The
recommended maximum pulse width during PWM
dimming is 2.5 ms, however this only applies to the Low
pulse interval. Pulse durations extending past 2.5 ms may
cause the device to enter full shutdown mode. The LED
channel response time is much longer if the device has been
in shutdown mode.
can be achieved with PWM clock frequencies in the range
of 100 Hz to 2 kHz. Pulse width intervals of 1 ms, allows up
to 1000:1 dimming ratio at 1 kHz PWM frequency.
One or Two LED String Applications
LEDs by connecting together some LED pins. Also for
applications requiring LED current greater than 175 mA,
LED channels can be tied together, assuming the supply is
suitable to drive the load. Figure 27 shows a typical
application for driving a single string of LEDs. The LED
current is equal to four times the channel current.
strings of LEDs. The LED current is equal to two times the
channel current.
OFF... ON... DIM...
OFF... ON... DIM...
V
V
V
V
IN
During PWM dimming, the recommended minimum
For most applications, a maximum dimming resolution
The CAT4106 can be used to drive one or two strings of
Figure 28 shows a typical application for driving two
L
Figure 28. Application Circuit for Two LED Strings
L
IN
Figure 27. Application Circuit for One LED String
R1
R1
C2
C1
C2
C1
R3
R3
R2
R2
VIN
VCTRL
FB
EN/PWM
RSET
VIN
VCTRL
FB
EN/PWM
RSET
L
L
GND
GND
CAT4106
CAT4106
SW
SW
PGND
PGND
D
VFMAX
VFMAX
C3
VFMIN
FAULT
D
FAULT
VFMIN
LED1
LED2
LED3
LED4
LED1
LED2
LED3
LED4
C3
(open drain pull−down)
(open drain pull−down)
LED Fault Detection
LED Fault Detection
R4
R5
R8
R8
R4
R5
R6
R7
R6
R7
V
V
IN
IN