MAX16803EVKIT+BJT Maxim Integrated Products, MAX16803EVKIT+BJT Datasheet - Page 2

• Manufacturer Part Number: MAX16803EVKIT+BJT
• Description: EVAL KIT FOR MAX16803
• Manufacturer: Maxim Integrated Products

Specifications of MAX16803EVKIT+BJT

• Current - Output / Channel: 1A
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 38V
• Features: Dimmable, Extra 5V Output
• Voltage - Input: 6.5 ~ 40V
• Utilized Ic / Part: MAX16803
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

•
The MAX16803EVKIT+BJT EV kit is fully assembled
and tested. Follow the steps below to verify board oper-
ation. Caution: Do not turn on the power supply until
all connections are completed.
1) Connect a 0 to 30V (or above), 1.5ADC power sup-
2) Close jumpers J2, J5, and J7.
3) Place jumper J3 between pin 1 (DIM) and pin 2 (+5V).
4) Open all pins of jumper J4 to select 450mA output
5) Connect one 1A-rated LED string with 3 LEDs in
6) Turn on the power supply and increase the input
7) Increase the supply voltage to 13V and the LED
The MAX16803EVKIT+BJT EV kit demonstrates a
high-current LED driver with accurate current control
based on the MAX16803 current regulator. This EV kit
is capable of supplying regulated output currents of
up to 1A and can run at supply voltages between 6.5V
to 40V.
The MAX16803EVKIT+BJT EV kit features PWM dim-
ming for control of the LED brightness by varying the
duty cycle of the PWM input signal. Users can select
between three levels of LED currents by setting jumper
J4. See Table 1 for jumper settings. The
MAX16803EVKIT+BJT EV kit also includes a connec-
tion for the 5V-regulated output and access to the on-
board current-sense resistor.
The output current can be set to 450mA, 750mA, or 1A
by adjusting the position of jumper J4. See Table 1 for
jumper settings. The output current can be adjusted by
MAX16803EVKIT+BJT Evaluation Kit+
2
0 to 30V (or above), 1.5A power supply
ply to VIN.
current.
series between LED+ and LED-.
voltage to above 10V. The LED should light up with
full brightness. Measure the LED current to confirm
450mA ± 3.5%.
current will remain stable. Measure the LED current
to show 450mA ± 3.5%. Measure voltage across
V5 to show 5.28V ± 5%.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Recommended Equipment
Detailed Description
Output Current Setting
Quick Start
Procedure
replacing resistors R2 or R3 with value calculated using
the following equation:
where R
between CS+ and CS-, and I
current.
The PWM dimming controls the LED brightness by
adjusting the duty cycle of the PWM input signal con-
nected to the DIM input. A high at the PWM_IN input
turns on the output current and a low turns off the LED
current. Connect a signal with amplitude between 5V
and 40V and with frequency between 100Hz–2kHz, and
vary the duty cycle to adjust the LED brightness. LED
brightness increases when duty cycle increases and
vice versa. Duty cycle can be as low as 10%, even at a
PWM frequency of 2kHz.
The 5V regulator can be used to power other compo-
nents from the V5 connector. The 5V output can supply
up to 4mA of current and is not disabled during PWM low.
The power dissipation in the MAX16803 can be calcu-
lated using the following equation:
where P
the output current of MAX16803 (the base current of
Q1), and V
OUT of this device.
Thermal shutdown turns the device off if power dissipa-
tion in the MAX16803 causes the junction temperature
to reach +155°C (typ).
The power dissipation in BJT can be calculated using
the following equation:
where P
emitter current of Q1, which is the actual LED current,
and V
emitter of the BJT. V
across the LED string and V
across the current-sense resistor, equal to 203mV.
P
2
= I
CE
2
TotalSensor
1
E
is the voltage drop between collector and
is the power dissipation in BJT, Q1. I
is the power dissipation in MAX16803, I
x V
DROP
CE
R
TotalSensor
= I
is the voltage drop between IN and
is the external current-sense resistor
P
OUT
1
and Thermal Management
= I
FDLED
x (V
B
x V
=
IN
5V-Regulated Output
OUT
DROP
– V
is the forward voltage
0 203
I
RSENSE
OUT
Power Dissipation
.
FDLED
is the desired output
PWM Dimming
is the voltage
– V
RSENSE
E
is the
)
B
is