MAX16833 Datasheet, PDF (8/22 Pages) Maxim Integrated Products – High-Voltage HB LED Drivers with Integrated High-Side Current Sense

High-Voltage HB LED Drivers with
Integrated High-Side Current Sense
Pin Description
PIN
NAME
FUNCTION
1
LFRAMP
(MAX16833)
Low-Frequency Ramp Output. Connect a capacitor from LFRAMP to ground to program the ramp
frequency, or connect to SGND if not used. A resistor can be connected between LFRAMP and RT/
SYNC to dither the PWM switching frequency to achieve spread spectrum.
REF
1.64V Reference Output. Connect a 1FF ceramic capacitor from REF to SGND to provide a stable
(MAX16833B) reference voltage. Connect a resistive divider from REF to ICTRL for analog dimming.
PWM Switching Frequency Programming Input. Connect a resistor (RRT) from RT/SYNC to SGND to
set the internal clock frequency. Frequency = (7.350 x 10⁹)/RRT.
2
RT/SYNC An external pulse can be applied to RT/SYNC through a coupling capacitor to synchronize the
internal clock to the external pulse frequency. The parasitic capacitance on RT/SYNC should be
minimized.
3
SGND
Signal Ground
4
ICTRL
Analog Dimming-Control Input. The voltage at ICTRL sets the LED current level when VICTRL < 1.2V.
For VICTRL > 1.4V, the internal reference sets the LED current.
5
COMP
Compensation Network Connection. For proper compensation, connect a suitable RC network from
COMP to ground.
6
FLT
Active-Low, Open-Drain Fault Indicator Output. See the Fault Indicator (FLT) section.
7
PWMDIM ^{PWM Dimming Input. When PWMDIM is pulled low, DIMOUT is pulled high and PWM switching is}
disabled. PWMDIM has an internal pullup resistor, defaulting to a high state when left unconnected.
LED String Overvoltage-Protection Input. Connect a resistive divider between ISENSE+, OVP, and
8
OVP
SGND. When the voltage on OVP exceeds 1.23V, a fast-acting comparator immediately stops PWM
switching. This comparator has a hysteresis of 70mV.
9
DIMOUT Active-Low External Dimming p-Channel MOSFET Gate Driver
Negative LED Current-Sense Input. A 100I resistor is recommended to be connected between
10
ISENSE- ISENSE- and the negative terminal of the LED current-sense resistor. This preserves the absolute
maximum rating of the ISENSE- pin during LED short circuit.
11
ISENSE+
Positive LED Current-Sense Input. The voltage between ISENSE+ and ISENSE- is proportionally
regulated to the lesser of VICTRL or 1.23V.
12
CS
Switching Regulator Current-Sense Input. Add a resistor from CS to switching MOSFET current-sense
resistor terminal for programming slope compensation.
13
PGND
Power Ground
14
NDRV
External n-channel MOSFET Gate-Driver Output
15
VCC
7V Low-Dropout Voltage Regulator Output. Bypass VCC to PGND with a 1FF (min) ceramic capacitor.
16
IN
Positive Power-Supply Input. Bypass IN to PGND with at least a 1FF ceramic capacitor.
—
EP
Exposed Pad. Connect EP to the ground plane for heatsinking. Do not use EP as the only electrical
connection to ground.
8   _______________________________________________________________________________________