MAX8790ETP+ Maxim Integrated Products, MAX8790ETP+ Datasheet - Page 8

• Manufacturer Part Number: MAX8790ETP+
• Description: IC LED DRVR WHITE BCKLGT 20-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Backlight, White LEDr

Specifications of MAX8790ETP+

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 6
• Internal Driver: No
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 1MHz
• Voltage - Supply: 4.5 V ~ 5.5 V, 5.5 V ~ 26 V
• Voltage - Output: 5V
• Mounting Type: Surface Mount
• Package / Case: 20-TQFN Exposed Pad
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 25mA
• Internal Switch(s): Yes
• Low Level Output Current: 1000000 uA (Typ)
• High Level Output Current: 25.75 mA
• Operating Supply Voltage: 4.5 V to 26 V
• Maximum Supply Current: 2 mA
• Maximum Power Dissipation: 1349 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Efficiency: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Six-String White LED Driver with Active
Current Balancing for LCD Panel Applications
(Circuit configuration 1, V
8
_______________________________________________________________________________________
PIN
10
1
2
3
4
5
6
7
8
9
NAME
SHDN
GND
OSC
ENA
BRT
FB1
FB2
FB3
FB4
FB5
(BRT = 100%, 2 LEDs SHORT ON FB3)
LED-SHORT FAULT PROTECTION
IN
O sci l l ator Fr eq uency S el ecti on P i n. C onnect OS C to V
1M H z. C onnect O S C to G N D to set the fr eq uency to 500kH z. Fl oat OS C to set the fr eq uency to 750kH z.
Anal og D i m m i ng E nab l e. E N A sets the P WM contr ol m od e. S et E N A LOW to enab l e d i r ect D P WM d i m m i ng .
S et E N A H IGH to enab l e anal og d i m m i ng . In b oth m od es, the d uty cycl e of the P WM si g nal at the BRT i np ut
contr ol s the LE D cur r ent char acter i sti cs. S ee the D i m m i ng C ontr ol secti on for a com p l ete d escr i p ti on.
Brightness Control Input. The duty cycle of this digital input signal controls the LED current characteristics.
The allowable frequency range is 100Hz to 500Hz in analog dimming mode. The duty cycle can be 100%
to 1%. The BRT frequency can go above 500Hz in direct DPWM mode as long as the BRT pulse width is
greater than 50µs minimum. See the Dimming Control section for a complete description.
Shutdown Control Input. The MAX8790 shuts down when SHDN is less than 0.8V. Pulling SHDN above
2.1V enables the MAX8790. SHDN can be connected to the input voltage if desired.
LED String 1 Cathode Connection. FB1 is the open-drain output of an internal regulator, which controls
current through FB1. FB1 can sink up to 25mA. If unused, connect FB1 to GND.
LED String 2 Cathode Connection. FB2 is the open-drain output of an internal regulator, which controls
current through FB2. FB2 can sink up to 25mA. If unused, connect FB2 to GND.
LED String 3 Cathode Connection. FB3 is the open-drain output of an internal regulator, which controls
current through FB3. FB3 can sink up to 25mA. If unused, connect FB3 to GND.
Ground
LED String 4 Cathode Connection. FB4 is the open-drain output of an internal regulator, which controls
current through FB4. FB4 can sink up to 25mA. If unused, connect FB4 to GND.
LED String 5 Cathode Connection. FB5 is the open-drain output of an internal regulator, which controls
current through FB5. FB5 can sink up to 25mA. If unused, connect FB5 to GND.
= 12V, V
10ms/div
SHDN
= V
MAX8790 toc17
IN
, LEDs = 8 series x 6 parallel strings, ISET = V
Typical Operating Characteristics (continued)
0V
0V
0V
0A
V
1V/div
V
10V/div
V
20V/div
I
1A/div
L
FB3
FB1
OUT
FUNCTION
C C
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0
to set the step - up conver ter ’ s osci l l ator fr eq uency to
7
vs. INPUT VOLTAGE (BRT = 100%)
750kHz
LED CURRENT BALANCING
INPUT VOLTAGE (V)
CC
12
, T
A
1MHz
= +25°C, unless otherwise noted.)
17
Pin Description
500kHz