MAX8785AETI+T Maxim Integrated Products, MAX8785AETI+T Datasheet - Page 11

• Manufacturer Part Number: MAX8785AETI+T
• Description: IC CCFL CTRL 28-TQFN
• Manufacturer: Maxim Integrated Products
• Type: CCFL Controllerr

Specifications of MAX8785AETI+T

• Current - Supply: 1.5mA
• Voltage - Supply: 4.5 V ~ 28 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Frequency: -
• Lead Free Status / Rohs Status: Details

The MAX8785A is a full-bridge CCFL controller for piezo-
electric transformer-based CCFL inverters. The full-
bridge topology provides a high-spectral purity
sinusoidal drive to help efficiently operate the piezoelec-
tric transformer. The MAX8785A uses feed-forward
Figure 2. MAX8785A Block Diagram
COMP
BATT
RATE
GND
VFB
OLF
V
IFB
HF
CC
. .
RECT
F.W.
REGULATOR
______________________________________________________________________________________
800mV
1mA
IFB
LINEAR
230mV
2.25V
Detailed Description
800mV
1.2V
ERROR
AMPLIFIER
4.12V
OVERVOLTAGE
COMPARATOR
SHORT-CIRCUIT
COMPARATOR
OPEN-LAMP
COMPARATOR
OLF
COMPARATOR
3.25V
VCO
BIAS
SUPPLY
UVLO
COMPARATOR
EN
EN
RAMP
Piezoelectric Transformers
1-SHOT
BLOCK
DELAY
FAULT
TFLT
V
DC
Full-Bridge Controller for
FLT
PWM CONTROL LOGIC
control to adjust the duty cycle that effectively regulates
lamp current during line transients and maintains rela-
tively constant switching frequency. The rate of the feed-
forward ramp signal can be adjusted with an external
resistor to accommodate different input voltage ranges
and different types of piezoelectric transformers.
PWM
COMPARATOR
CURRENT-LIMIT
COMPARATOR
PRIMARY
1.6V
CONTROL
MACHINE
DRIVER
GATE-
STATE
MUX
400mV
LX1
LX2
DPWM OSC
CONTROL
DIMMING
MAX8785A
PLL AND
LOGIC
VDD2
Block Diagram
VDD1
LF
LSYNC
PCOMP
SEL
CNTL
SHDN
V
BST1
GH1
LX1
V
BST2
GH2
LX2
GL1
PGND
GL2
DD1
DD2
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