MAX16833AUE+T Maxim Integrated Products, MAX16833AUE+T Datasheet - Page 11

• Manufacturer Part Number: MAX16833AUE+T
• Description: IC HB LED DVR CURR SENSE 16TSSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX16833AUE+T

• Topology: Flyback, Low Side, PWM, SEPIC, Step-Down (Buck), Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: No
• Type - Primary: Automotive, General Purpose
• Type - Secondary: High Brightness LED (HBLED)
• Frequency: 100kHz ~ 1MHz
• Voltage - Supply: 5 V ~ 65 V
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP (0.173", 4.40mm Width) Exposed pad
• Operating Temperature: -40°C ~ 125°C
• Current - Output / Channel: 3A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / Rohs Status: Details

The MAX16833/MAX16833B/MAX16833C/MAX16833D
are peak current-mode-controlled LED drivers for boost,
buck-boost, SEPIC, flyback, and high-side buck topolo-
gies. A low-side gate driver capable of sinking and
sourcing 3A can drive a power MOSFET in the 100kHz
to 1MHz frequency range. Constant-frequency peak
current-mode control is used to control the duty cycle
of the PWM controller that drives the power MOSFET.
Externally programmable slope compensation prevents
subharmonic oscillations for duty cycles exceeding 50%
when the inductor is operating in continuous conduction
mode. Most of the power for the internal control circuitry
inside the ICs is provided from an internal 5V regulator.
The gate drive for the low-side switching MOSFET is
provided by a separate V
designed to drive an external p-channel in series with the
LED string provides wide-range dimming control. This
dimming driver is powered by a separate unconnected
reference -7V regulator. This feature provides extremely
fast PWM current switching to the LEDs with no transient
overvoltage or undervoltage conditions. In addition to
PWM dimming, the ICs provide analog dimming using a
DC input at the ICTRL input.
A single resistor from RT/SYNC to ground sets the
switching frequency from 100kHz to 1MHz, while an
external clock signal capacitively coupled to RT/SYNC
allows the ICs to synchronize to an external clock. The
switching frequency can be dithered for spread-spectrum
applications by connecting the LFRAMP output to RT/SYNC
through an external resistor in the MAX16833/MAX16833C.
In the MAX16833B/MAX16833D, the LFRAMP output is
replaced by a REF output, which provides a regulated
1.64V, 2% accurate reference that can be used with a
resistive divider from REF to ICTRL to set the LED cur-
rent. The maximum current from the REF output cannot
exceed 80FA.
Additional features include a fault-indicator output (FLT)
for short, overvoltage, or overtemperature conditions
and an overvoltage-protection (OVP) sense input for
overvoltage protection. In case of LED string short, for
a buck-boost configuration, the short-circuit current is
equal to the programmed LED current. In the case of
boost configuration, the ICs enter hiccup mode with
automatic recovery from short circuit.
______________________________________________________________________________________
Detailed Description
CC
regulator. A dimming driver
Integrated High-Side Current Sense
High-Voltage HB LED Drivers with
The ICs feature undervoltage lockout (UVLO) using the
positive power-supply input (IN). The ICs are enabled
when V
abled when V
The UVLO is internally fixed and cannot be adjusted.
There is a startup delay of 1024 clock cycles on power-
up after the UVLO threshold is crossed. There is a 3.3Fs
delay on power-down on the falling edge of the UVLO.
The ICs require an external p-channel MOSFET for PWM
dimming. For normal operation, connect the gate of the
MOSFET to the output of the dimming driver (DIMOUT).
The dimming driver can sink up to 25mA or source up
to 50mA of peak current for fast charging and discharg-
ing of the p-MOSFET gate. When the PWMDIM signal is
high, this driver pulls the p-MOSFET gate to 7V below
the ISENSE+ pin to completely turn on the p-channel
dimming MOSFET.
The ICs drive an external n-channel switching MOSFET.
NDRV swings between V
source 3A of peak current, allowing the ICs to switch
MOSFETs in high-power applications. The average cur-
rent demanded from the supply to drive the external
MOSFET depends on the total gate charge (Q
the operating frequency of the converter, f
following equation to calculate the driver supply current
I
The ICs offer a dimming input (PWMDIM) for pulse-width
modulating the output current. PWM dimming can be
achieved by driving PWMDIM with a pulsating voltage
source. When the voltage at PWMDIM is greater than
1.23V, the PWM dimming p-channel MOSFET turns on
and the gate drive to the n-channel switching MOSFET is
also enabled. When the voltage on PWMDIM drops 70mV
below 1.23V, the PWM dimming MOSFET turns off and
the n-channel switching MOSFET is also turned off. The
COMP capacitor is also disconnected from the internal
transconductance amplifier when PWMDIM is low. When
left unconnected, a weak internal pullup resistor sets this
input to logic-high.
NDRV
n-Channel MOSFET Switch Driver (NDRV)
required for the switching MOSFET:
IN
exceeds the 4.6V (typ) threshold and are dis-
Dimming MOSFET Driver (DIMOUT)
IN
Pulse-Dimming Input (PWMDIM)
drops below the 4.35V (typ) threshold.
I
NDRV
CC
= Q
and PGND. NDRV can sink/
G
x f
SW
SW
. Use the
UVLO
G
) and
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