Rainbow Electronics MAX16822B - Manual

General Description
The MAX16822A/MAX16822B step-down constant-cur-
rent high-brightness LED (HB LED) drivers provide a
cost-effective design solution for automotive
interior/exterior lighting, architectural and ambient light-
ing, LED bulbs, and other LED illumination applications.
The MAX16822A/MAX16822B operate from a +6.5V to
+65V input-voltage range. A high-side current-sense
resistor adjusts the output current up to 350mA and a
dedicated pulse-width modulation (PWM) input enables
pulsed LED dimming over a wide range of brightness
levels.
These devices are well suited for applications requiring
a wide input-voltage range. The high-side current sens-
ing and an integrated current-setting circuitry minimize
the number of external components while delivering an
average output current with ±3% accuracy. A hysteretic
control method ensures excellent input supply rejection
and fast response during load transients and PWM dim-
ming. The MAX16822A allows 10% current ripple and
the MAX16822B allows 30% current ripple. Both
devices operate up to a switching frequency of 2MHz,
thus allowing the use of small-sized components.
The MAX16822A/MAX16822B offer an analog dimming
feature that reduces the output current by applying an
external DC voltage below the internal 2V threshold volt-
age from TEMP_I to GND. TEMP_I also sources 25µA to
a negative temperature coefficient (NTC) thermistor con-
nected between TEMP_I and GND, thus providing an
analog thermal-foldback feature that reduces the LED
current when the temperature of the LED string exceeds
a specified temperature point.
An additional feature includes thermal-shutdown pro-
tection that turns off the LX driver when the junction
temperature exceeds +165°C.
The MAX16822A/MAX16822B operate over the -40°C to
+125°C automotive temperature range and are available
in an 8-pin SO package.
Applications
Architectural, Industrial, and Ambient Lighting
Automotive RCL, DRL, and Fog Lights
Heads-Up Displays
Indicator and Emergency Lighting
Features
♦ High-Efficiency Solution
♦ 6.5V to 65V Input-Voltage Range
♦ On-Board 65V, 0.85Ω Power MOSFET
♦ Hysteretic Control: Up to 2MHz Switching
Frequency
♦ ±3% LED Current Accuracy
♦ 200mV Current-Sense Reference
♦ Resistor-Programmable Constant LED Current
♦ Integrated High-Side Current Sense
♦ Thermal-Foldback Protection/Linear Dimming
♦ Thermal-Shutdown Protection
♦ Available in an 8-Pin SO Package
♦ -40°C to +125°C Operating Temperature Range
MAX16822A/MAX16822B
2MHz, High-Brightness LED Drivers with
Integrated MOSFET and High-Side Current Sense
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
LX
LX PGND
1
2
8
7
TEMP_I
DIM IN
GND
CS
3
4
6
5
MAX16822A
MAX16822B
L1
C2
ON
OFF
D1
HB LEDs
NTC*
*OPTIONAL
R SENSE
V IN
C1
Typical Application Circuit
19-4141; Rev 1; 6/08
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
EVALUATION KIT
AVAILABLE
+ Denotes a lead-free/RoHS-compliant package.
PART TEMP RANGE PIN-PACKAGE
MAX16822AASA+ -40°C to +125°C 8 SO
MAX16822BASA+ -40°C to +125°C 8 SO
Pin Configuration appears at end of data sheet.