MAX20070 Datasheet, PDF (1/34 Pages) Maxim Integrated Products – LED Backlight Driver

MAX20070
Integrated TFT Power Supply and
LED Backlight Driver
General Description
The MAX20070 is a highly integrated power supply and
LED backlight driver for automotive TFT-LCD applications.
The device integrates one buck-boost converter, one
boost converter, two gate-driver supplies, and a boost/
SEPIC converter that can power one to two strings of
LEDs in the display backlight.
The source-driver power supplies consist of a boost
converter and an inverting buck-boost converter that can
generate voltages up to +15V and -15V. Both source-
driver power supplies can deliver up to 100mA. The
positive source-driver supply regulation voltage (V_POS)
is set by connecting an external resistor-divider on FBP.
Connecting the FBP pin to ground sets the regulation
voltage (V_POS) to +6.5V. The negative source-driver
supply voltage (V_NEG) is always tightly regulated to -V_POS
within +50mV. The source-driver supplies use an input
voltage from 2.7V to 5.5V to generate the output voltages.
The gate-driver power supplies consist of regulated
charge pumps that generate up to +22V and -22V and can
deliver up to 3mA each. The regulation voltage (V_GVDD)
on the positive charge pump is set by a resistor-divider
on FBPG; the regulation voltage (V_GVEE) on the negative
charge pump is set by a resistor-divider on FBNG.
The IC features a dual-string LED driver that operates off
a separate input voltage (V_BATT) and can power up to two
strings of LEDs with 160mA (max) of current per string.
The startup and shutdown sequences for all power
domains is controlled using one of the seven preset
modes that are selectable through a resistor on SEQ.
The device is available in a 32-pin, 5mm x 5mm TQFN
package with an exposed pad, and operates over the
-40°C to +105°C ambient temperature range.
Applications
●● Automotive Dashboards
●● Automotive Central Information Displays
●● Automotive Head-Up Displays
●● Automotive Navigation Systems
Benefits and Features
●● Integrates both TFT Power Supplies and LED
Backlight Driver in One IC, Reducing Component
Count
●● Alleviates EMI Due to Spread Spectrum on Both
Source Driver Supplies and LED Driver
●● 5000:1 Dimming Ratio at 200Hz Dimming Frequency
●● Available in a 32-Pin (5mm x 5mm) TQFN with an
Exposed Pad for Heat Dissipation and Operates
Over the -40°C to +105°C Ambient Temperature
Range
Ordering Information and Simplified Operating Circuit
appear at end of data sheet.
Simplified Operating Circuit
BATTERY INPUT
D3-2
D3-1
VGVDD
C9
TFT POWER
INPUT
IN
C1
PGVDD
C7
C3
DP
R4
R5
FBPG
VGVEE
D5
C11
C20
R6
AGND
DGVDD
C10
D6
D11
DGVEE
DN
C19
D12
FBNG
BATT
MAX20070
R7
C14
AGND
ENABLE INPUT
FAULT OUTPUT
REF
R8
SEQ
GND
EN
FLT
EP
AGND
L1
D1
C2
LGND
VCC
DRAIN
OVP
COMP
CS
ISET
C22
AGND
C21
LGND
R17
R12
R11
R15
PGND
OUT1
OUT2
LGND
DIM
LGND
C13
AGND
LGND
L3
LX
HVINP
FBP
POS
D13
VPOS
C12
VNEG
NEG
C5 ^{TFT POWER}
INPUT
INN
LXN
D2
C6
L2
R16
DIM
INPUT TFT POWER
INPUT
C23
AGND
LGND
19-7118; Rev 0; 9/14