MAX16828EVKIT+ Maxim Integrated Products, MAX16828EVKIT+ Datasheet - Page 8

• Manufacturer Part Number: MAX16828EVKIT+
• Description: EVALUATION KIT FOR MAX16828
• Manufacturer: Maxim Integrated Products

Specifications of MAX16828EVKIT+

• Current - Output / Channel: 200mA
• Outputs And Type: 1, Non-Isolated
• Features: Dimmable, Extra 5V Output
• Voltage - Input: 6.5 ~ 40V
• Utilized Ic / Part: MAX16828
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

High-Voltage, 100mA/200mA Adjustable Linear
High-Brightness LED Drivers with PWM Dimming
Figure 1 shows PWM dimming operation for the
MAX16815/MAX16828 with an ICM7555 timer. The
ICM7555 provides adjustable duty cycle using two
external resistors and a capacitor. In TAIL operation,
the output of the ICM7555 feeds into DIM and lights up
the LEDs. The LED’s brightness depends on the duty
cycle of the ICM7555. When V
pulled up to V
abled and the LEDs light up to full brightness. See the
ICM7555 data sheet for formulas to calculate the dim-
ming frequency and the duty cycle.
With a minimum number of external components, the
MAX16815/MAX16828 provide LED current thermal
foldback using a negative temperature coefficient
(NTC) thermistor. Figure 2 shows a thermistor connect-
ed to V5 and the CS+ of the MAX16815/MAX16828. As
the temperature increases, the voltage drop across R2
increases, causing the LED current to decrease.
The application circuit in Figure 3 implements a two-
level brightness current for TAIL/STOP lights. In TAIL
operation, Q1 is off and R1 sets the output current. In
Figure 1. PWM Dimming Operation with ICM7555 Timer
8
_______________________________________________________________________________________
I
LED
= [V
STOP
*R4 < 300kΩ
C2
R3
RSNS
LED Current Thermal Foldback
. The PWM dimming operation is dis-
- (R2 / R
Two Brightness Levels for
DIS
TH
TRG
R2
ICM7555
T
) (V
Other Applications
STOP
STOP
TAIL/STOP Lights
TAIL
V5
IN
GND
OUT
- V
is present, DIM is
RSNS
D3
R1
)]/R1
D4
R4*
D1
D2
C1
STOP operation, Q1 turns on and the output current is
set by a parallel combination of R1 and R2. Figure 4
shows an application circuit with the MAX16815/
MAX16828 using a single BJT to provide high output
current. For proper operation:
where V
of the external BJT and V
voltage of all series connected LEDs.
Figure 2. LED Current Thermal Foldback with an NTC
Thermistor
V
C1
IN
V
IN
DIM
GND
DIMMING
IN(MIN)
PWM
CESAT(MAX)
MAX16815
MAX16828
> V
IN
DIM
GND
CESAT(MAX)
MAX16815
MAX16828
is the maximum saturation voltage
OUT
CS+
CS-
V5
+5V REG
FT(MAX)
OUT
CS+
CS-
V5
+ V
C2
FT(MAX)
is the total forward
LEDs
C2
R
SENSE
+ V
RT
R2
RSNS
LEDs
R1