CAT3661 Datasheet, PDF (8/12 Pages) ON Semiconductor – 1-Channel Low-Power LED Driver

CAT3661
Table 5. PIN DESCRIPTION
Pin No.
Pin Name
Description
1
RSET
Connect resistor RSET to set the LED current
2
nFLTB
Battery Fault output, Open drain output. (Active low)
3
nFLTL
LED Fault output, Open drain output. (Active low)
4
EN
Device enable (Active high)
5
LED
LED cathode terminal
6
NC
Not connected inside the package
7
NC
Not connected inside the package
8
VOUT
Charge pump output connected to the LED anodes
9
C2−
Bucket capacitor 2 Negative terminal
10
C2+
Bucket capacitor 2 Positive terminal
11
C1+
Bucket capacitor 1 Positive terminal
12
C1−
Bucket capacitor 1 Negative terminal
13
VIN
Positive supply connection to battery
14
ADJH
Battery trip point threshold adjust high
15
ADJL
Battery trip point threshold adjust low
16
GND
Ground supply connection
TAB
GND
Connect to GND on the PCB
Pin Functions
VIN is the supply pin for the device. A small 1 mF ceramic
bypass capacitor is required between the VIN pin and
ground near the device.
EN is the device enable pin. Levels of logic high and logic
low are set at 1.3 V and 0.4 V respectively to enable
interface to low voltage controllers. EN pin is compatible
with voltages higher than VIN.
VOUT is the charge pump output that is connected to the
LED anodes. A small 1 mF ceramic bypass capacitor is
required between the VOUT pin and ground near the device.
GND is the ground reference for the charge pump. This pin
must be connected to the ground plane on the PCB.
C1+, C1− are connected to each side of the ceramic bucket
capacitor C1.
C2+, C2− are connected to each side of the ceramic bucket
capacitor C2.
LED provides the internal regulated current source for the
LED cathode. This pin enters high−impedance ‘zero’
current state whenever the device is placed in shutdown
mode.
TAB is the exposed pad underneath the package. For best
thermal performance, the tab should be soldered to the PCB
and connected to the ground plane.
RSET is connected to a resistor (RSET) to set the full scale
current for the LEDs. The voltage at this pin regulated to
0.6 V. The ground side of the external resistor should be star
connected back to the GND of the PCB. In shutdown mode,
RSET becomes high impedance.
nFLTL is an active low open−drain output that provides a
fault flag for an open/short LED condition. If used, this pin
requires a pull−up resistor.
nFLTB is an active low open−drain output that provides a
fault flag for a low battery condition. If used, this pin
requires a pull−up resistor. nFLTB and nFLTL can be
shorted together for one Fault output (ORed function).
ADJH is an external connection to the top of the low battery
sense resistor divider network. This pin should be shorted to
VIN if a trip point of 2.4 V is required.
ADJL is an external connection to the bottom of the low
battery sense resistor divider network. This pin should be
shorted to GND if a trip point of 2.4 V is required.
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