MAX1599ETA+T Maxim Integrated Products, MAX1599ETA+T Datasheet - Page 6

• Manufacturer Part Number: MAX1599ETA+T
• Description: IC LED DRIVR WHITE BCKLGT 8-TDFN
• Manufacturer: Maxim Integrated Products
• Type: Backlight, White LEDr

Specifications of MAX1599ETA+T

• Constant Current: Yes
• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 400kHz ~ 600kHz
• Voltage - Supply: 2.6 V ~ 5.5 V
• Voltage - Output: 26V
• Mounting Type: Surface Mount
• Package / Case: 8-TDFN Exposed Pad
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 700mA
• Internal Switch(s): Yes
• Efficiency: 87%
• Number Of Segments: 6
• Operating Supply Voltage: 2.6 V to 5.5 V
• Maximum Power Dissipation: 1950 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

High-Efficiency, 26V Step-Up Converters
for Two to Six White LEDs
The MAX1561/MAX1599s’ high efficiency and small size
make them ideally suited to drive up to six series-con-
nected LEDs. The device operates as a boost DC-DC
converter that regulates output current rather than volt-
age. The MAX1561/MAX1599 provide even illumination
by sourcing the same output current through each LED,
eliminating the need for expensive factory calibration.
The fast 1MHz (500kHz for the MAX1599) internal oscil-
lator allows for a small inductor and small input and out-
put capacitors while minimizing input and output ripple.
The single analog control input allows easy adjustment
of LED brightness and on/off control. This allows either
simple logic-level on/off control, analog voltage control,
or PWM duty-cycle control of both brightness and shut-
down. In shutdown, supply current is reduced to a low
0.3µA. A soft-start gradually illuminates the LEDs, elimi-
nating the inrush current during startup.
The MAX1561/MAX1599 attain soft-start by charging
C
rises above 1.25V, the internal MOSFET begins switch-
ing at a reduced duty cycle. When V
2.25V, the duty cycle is at its maximum. See the Typical
Operating Characteristics for an example of soft-start
operation.
6
Exposed
COMP
_______________________________________________________________________________________
PIN
Pad
1
2
3
4
5
6
7
8
gradually with a current source. When V
NAME
COMP
PGND
CTRL
GND
OUT
CS
EP
LX
IN
Overvoltage Sense. When V
drops below 25V, then the IC reenters soft-start. Connect a 0.1µF capacitor from OUT to PGND.
Input Voltage Supply. Input voltage range is 2.6V to 5.5V. Connect a 2.2µF capacitor from IN to PGND.
Brightness Control Input. LED brightness is controlled by the voltage applied to CTRL. Varying the voltage
from 0.24V to 1.62V adjusts the brightness from dim to bright, respectively. Any voltage above 1.62V does
not increase brightness. If CTRL is held below 100mV for more than 8.2ms (16.4ms for the MAX1599), the
IC shuts down.
Current-Sense Feedback Input. Connect a resistor from CS to GND to set the LED bias current. The
voltage at CS regulates to V
Compensation Input. Connect a 0.1µF capacitor (C
converter and controls soft-start. C
Ground. Connect to PGND and the exposed pad directly under the IC.
Power Ground. Connect to GND and the exposed pad directly under the IC.
Inductor Connection. This pin is high impedance during shutdown.
Ground. Connect directly to GND and PGND under the IC.
Detailed Description
COMP
Soft-Start
rises above
CTRL
OUT
COMP
is greater than 27V, the internal N-channel MOSFET turns off until V
/ 10 or 0.162V, whichever is lower.
COMP
discharges to GND when in shutdown.
The MAX1561/MAX1599 enter shutdown when V
less than 100mV for more than 8.2ms (16.4ms for the
MAX1599). In shutdown, supply current is reduced to
0.3µA by powering down the entire IC except for the
CTRL voltage-detection circuitry. C
during shutdown, allowing the device to reinitiate soft-
start when it is enabled. Although the internal N-chan-
nel MOSFET does not switch in shutdown, there is still
a DC current path between the input and the LEDs
through the inductor and Schottky diode. The minimum
forward voltage of the LED array must exceed the max-
imum input voltage to ensure that the LEDs remain off
in shutdown. However, with two or more LEDs, the for-
ward voltage is large enough to keep leakage current
low, less than 1µA (typ). Typical shutdown timing char-
acteristics are shown in the Typical Operating
Characteristics.
Overvoltage lockout (OVLO) occurs when V
above 27V. The protection circuitry stops the internal
MOSFET from switching and causes V
to 0V. The device comes out of OVLO and into soft-
start when V
FUNCTION
COMP
) from COMP to GND. C
OUT
falls below 25V.
Overvoltage Protection
Pin Description
COMP
COMP
stabilizes the
COMP
is discharged
Shutdown
to decay
OUT
CTRL
OUT
is
is