MAX16816 Datasheet, PDF (12/33 Pages) Maxim Integrated Products – Programmable Switch-Mode LED Driver with Analog-Controlled PWM Dimming

Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
Pin Description
PIN
1, 24
2
NAME
N.C.
UVEN
No Connection. Not internally connected.
FUNCTION
Undervoltage Lockout (UVLO) Threshold/Enable Input. UVEN is a dual-function adjustable UVLO threshold
input with an enable feature. Connect UVEN to V_CC through a resistive voltage-divider to program the UVLO
threshold. Connect UVEN directly to V_CC to use the 5.9V (max) default UVLO threshold. Apply a voltage
greater than 1.244V to UVEN to enable the device.
5V Regulator Output. REG1 is an internal low-dropout voltage regulator that generates a 5V (V_CC > 6V)
3
REG1 output voltage and supplies power to internal circuitry. Bypass REG1 to AGND through a 1µF ceramic
capacitor.
4
AGND ^{Analog Ground. Use proper single-point ground design and decoupling to avoid ground impedance loop}
errors.
5
REF
Accurate 3V Buffered Reference Output. Connect REF to DIM through a resistive voltage-divider to apply a
DC voltage for analog-controlled dimming functionality. Leave REF unconnected if unused.
Dimming Control Input. Connect DIM to an external PWM signal for PWM dimming. For analog-controlled
6
DIM dimming, connect DIM to REF through a resistive voltage-divider. The dimming frequency is 200Hz under
these conditions. Connect DIM to AGND to turn off the LEDs.
7
8
9, 10, 11
12
RTSYNC
CLKOUT
I.C.
COMP
Sync Input/Output. The internal PWM clock is selectable through the RTOF EEPROM bit. Connect an
external resistor to RTSYNC and set the RTOF register to ‘0’ to select a clock frequency between 125kHz
and 500kHz. Set RTOF register to ‘0’ and connect RTSYNC to an external clock to synchronize the device
with external clock. Set RTOF register to ‘1’ to use the fixed 125kHz oscillator. Under these conditions,
RTSYNC is powered off and may be left in any state. See the Oscillator, Clock, and Synchronization section.
Clock Output. CLKOUT buffers the oscillator/clock. Connect CLKOUT to the SYNC input of another device
to operate the MAX16816 in a multichannel configuration. CLKOUT is a logic output.
Internally Connected. Must be connected to AGND.
Error-Amplifier Output. Connect the compensation network from COMP to FB for stable closed-loop control.
Use low-leakage ceramic capacitors in the feedback network.
Current-Sense Voltage Output. CS outputs a voltage proportional to the current sensed through the current-
13
CS
sense amplifier. Connect CS through a passive network to FB as dictated by the chosen compensation
scheme.
14
FB
Error-Amplifier Inverting Input
Overvoltage Protection Input. Connect OV to HI through a resistive voltage-divider to set the overvoltage
15
OV
limit for the load. When the voltage at OV exceeds the 1.235V (typ) threshold, an overvoltage fault is
generated and the switching MOSFET turns off. The MOSFET is turned on again when the voltage at OV
drops below 1.17V (typ).
16, 17
18
SGND
DRV
Switching Ground. SGND is the ground for non-analog and high-current gate-driver circuitry.
Gate-Driver Output. Connect DRV through a series resistor to the gate of an external n-channel MOSFET to
reduce EMI. DRV can sink 1A or source 0.5A.
19
DRI Gate-Driver Supply Input. Connect DRI to REG2 to power the primary switching MOSFET driver.
20
SNS+ ^{Positive Peak Current-Sense Input. Connect SNS+ to the positive side of the switch current-sense resistor,}
R_SENSE.
12 ______________________________________________________________________________________