cat4106 ON Semiconductor, cat4106 Datasheet - Page 8

• Manufacturer Part Number: cat4106
• Description: 6w Quad Channel Dc/dc Led Driver With Diagnostics
• Manufacturer: ON Semiconductor

CAT4106
PIN DESCRIPTION
PIN DESCRIPTIONS
VIN is the supply pin for the device. The supply input
current needed for normal operation is approximately
2 mA plus 3 times I
PWM dimming, or whenever the converter is not
switching, the supply current will decrease by around
1 mA. The voltage applied at VIN should be kept
between 3 V and 5.5 V. A small ceramic bypass
capacitor of 0.1 μF or greater is recommended to be
in close proximity to the VIN pin.
EN/PWM is the device Enable and PWM dimming
control input for all LED channels. Guaranteed levels
of logic high and logic low are set at 1.3 V and 0.4 V
respectively. During normal PWM dimming, the entire
device remains fully biased and only the LED
channels are pulsed on/off. The device will only enter
zero current shutdown mode after the EN/PWM is
help low for at least 5 ms typically. This pin has an
internal pull-down resistor of 200 kΩ.
RSET is the voltage regulated control pin for sensing
the desired programming current level to be applied
on all LED channels. During normal operation, the
RSET pin is kept at 1.2 V and accurately monitors the
current level in the externally applied R1 resistor. The
current transfer ratio from RSET pin current to LED
pin current is 100.
Doc. No. MD-5037, Rev. A
EN/PWM
VFMAX
¯¯¯¯¯¯
FAULT
VFMIN
PGND
Name
RSET
CTRL
LED1
LED3
LED3
LED4
GND
TAB
N.C
SW
VIN
FB
TSSOP-16
TQFN-16
RSET
TAB
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
pin current. During intervals of
Function
LED1 cathode terminal
Signal Ground reference
Open/Short LED Fault detection output (active-low)
Power Ground Reference (DC/DC Power Switch)
Feedback reference (300 mV) for setting LED channel operating voltage
Internal power FET switch drain connection
Device Enable (active high) and PWM control input
Not connected
Supply voltage for the device
LED channel operating voltage (lowest of all 4 channels)
Comparator input for setting the LED string short-circuit voltage limit
Comparator input for setting the LED string open-circuit voltage limit
RSET resistor pin for setting the LED channel operating current
LED3 cathode terminal
LED3 cathode terminal
LED4 cathode terminal
Thermal pad (connect to GND and PGND)
8
LED1 to LED4 provide the regulated current source
for driving each of the LED strings with a tightly
matched
performance, the bias voltage on the LED channels
should be set at a nominal 0.6 V or higher. Each
channel is capable of driving a current up to 175 mA.
All channels immediately enter a high impedance
mode whenever the EN/PWM is taken LOW.
CTRL pin is a multiplexer output which selects the
lowest operating voltage appearing on any of the four
LED output drive channels. This control signal
represents the cathode terminal voltage of the LED
string with greatest forward voltage (V
resistor network from CTRL to FB can be used to set
the lowest operating voltage of each channel. External
current loading of the CTRL pin is recommended to be
less than 25 μA.
FB is the voltage feedback control pin for the internal
high power DC/DC converter. This pin has a high
impedance input and its voltage remains accurately
regulated to 0.3 V during normal steady state
operation
constant
current.
Characteristics subject to change without notice
To
© 2009 SCILLC. All rights reserved.
ensure
F
). An external
optimal