Datasheet

9Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Pin Description
PIN
NAME FUNCTION
TQFN TSSOP
1 4 NDRV
Gate Drive for Switching MOSFET. Connect NDRV to GATE directly or through a resistor
to control the rise and fall times of the gate drive.
2 5 DRV
5V Regulator Output. MOSFET gate-driver supply input. Bypass DRV to PGND with a
minimum of 1FF ceramic capacitor. Place the capacitor as close as possible to DRV
and PGND.
3 6 V
CC
Internal Circuitry Supply Voltage. Bypass V
CC
to SGND with a minimum of 0.1FF
ceramic capacitor. Place the capacitor as close as possible to V
CC
and SGND.
4 7 IN
Supply Input. Connect a 4.75V to 40V supply to IN. Bypass IN to PGND with a minimum
of 1FF ceramic capacitor. For a 5V Q10% supply voltage, connect V
IN
to V
CC
.
5 8 EN
Enable/Undervoltage Lockout (UVLO) Threshold Input. EN is a dual-function input.
Connect EN to V
IN
through a resistor-divider to program the UVLO threshold.
6 9 SGND
Signal Ground. SGND is the current return path connection for the low-noise analog
signals. Connect SGND, LEDGND, and PGND at a single point.
7 10 CFB
Current Foldback Reference Input. Connect a resistor-divider between IN, CFB, and
ground to set the current foldback threshold. When the voltage at CFB goes below
1.23V, the LED current starts reducing linearly. Connect to V
CC
to disable the current
foldback feature.
8 11 OV
Overvoltage Threshold Adjust Input. Connect a resistor-divider from the switching
converter output to OV and SGND. The OV comparator reference is internally set to 1.23V.
9 12 ISET
LED Current Adjust Input. Connect a resistor R
ISET
from ISET to SGND to set the
current through each LED string (I
LED
) according to the formula I
LED
= 1512V/R
ISET
.
10 13
FLT
Open-Drain, Active-Low Flag Output. FLT asserts when there is an open/short-LED
condition at the output or when there is a thermal shutdown event.
11 14 OUT2
LED String Cathode Connection 2. OUT2 is the open-drain output of the linear current
sink that controls the current through the LED string connected to OUT2. OUT2 sinks
up to 150mA.
12 15 LEDGND
LED Ground. LEDGND is the return path connection for the linear current sinks.
Connect SGND, LEDGND, and PGND at a single point.
13 16 OUT1
LED String Cathode Connection 1. OUT1 is the open-drain output of the linear current
sink that controls the current through the LED string connected to OUT1. OUT1 sinks
up to 150mA.
14 17 RT
Oscillator Timing Resistor Connection. Connect a timing resistor (R
RT
) from RT to SGND
to program the switching frequency. Apply an AC-coupled external clock at RT to
synchronize the switching frequency with an external clock source.
15 18 COMP
Switching Converter Compensation Input. Connect an RC network from COMP to SGND
(see the Feedback Compensation section).