MAX16815 Datasheet, PDF (7/11 Pages) Maxim Integrated Products – High-Voltage, 100mA/200mA Adjustable Linear High-Brightness LED Drivers with PWM Dimming

High-Voltage, 100mA/200mA Adjustable Linear
High-Brightness LED Drivers with PWM Dimming
SO Functional Diagram
DIM
IN
1.2V
EN
BANDGAP
AND 5V
V5
REGULATOR
THERMAL
SHUTDOWN
GND
MAX16815
MAX16828
0.8μA
IREG
DIFF
AMP
P
OUT
CS+
CS-
Detailed Description
+5V Regulator
The MAX16815/MAX16828 include a fixed +5V output
regulator that delivers up to 4mA of load current
throughout the 6.5V to 40V input voltage range.
Connect a 0.1µF compensation capacitor from V5 to
ground. Shorting V5 to ground disables the thermal
shutdown. V5 stays on during PWM dimming.
Thermal Protection
The MAX16815/MAX16828 enter a thermal-shutdown
mode in the event of overheating. This typically occurs
in overload or output short-circuit conditions. If the
junction temperature exceeds T_J = +159°C (typ), the
internal thermal-protection circuitry turns off the series
pass device. The MAX16815/MAX16828 recover from
thermal-shutdown mode once the junction temperature
drops by 24°C (typ). The devices therefore protect
themselves by thermal cycling in the event of a short-
circuit or overload condition. Shorting V5 to ground dis-
ables the thermal shutdown.
Applications Information
Programming the LED Current
The MAX16815/MAX16828 use a sense resistor across
CS+ and GND for the TDFN package or across CS+
and CS- for the SO package, to set the LED current.
The LED current is given by I_LED = V_RSNS/R_SENSE.
Input-Voltage Considerations
For proper operation, the minimum input voltage must
always be:
V_IN(MIN) ≥ V_RSNS(MAX) + V_FT(MAX) + ΔV_DO(MAX)
where V_FT(MAX) is the total forward voltage of all series
connected LEDs. The minimum operating voltage of the
device is +6.5V. The device operates below +6.5V;
however, output current may not meet the full regulation
specification (see the Typical Operating Characteristics)
and the V5 regulator will drop below 5V.
Low-Frequency PWM Dimming
at the Output
Provide a pulse to the dimming input (DIM) of the
MAX16815/MAX16828 to produce a PWM output.
Alternatively, connect DIM to IN and pulse IN.
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