MAX8595Z MAXIM [Maxim Integrated Products], MAX8595Z Datasheet - Page 5

• Manufacturer Part Number: MAX8595Z
• Description: High-Efficiency, 32V Step-Up Converters with TA Derating Option for 2 to 8 White LEDs
• Manufacturer: MAXIM [Maxim Integrated Products]

(Circuit of Figure 1, V
T
A
= +25°C, unless otherwise noted.)
PIN
with T
—
1
2
3
4
5
6
7
8
V
V
CTRL
I
OUT
LED
I
IN
NAME
COMP
PGND
CTRL
GND
OUT
High-Efficiency, 32V Step-Up Converters
_______________________________________________________________________________________
CS
IN
LX
EP
IN
A
= 3.6V, I
CTRL STEP RESPONSE
Derating Option for 2 to 8 White LEDs
Overvoltage Sense. When V
until V
from OUT to ground. In shutdown, V
Input Voltage Supply. The input voltage range is 2.6V to 5.5V. Connect a 2.2µF ceramic capacitor
from IN to GND.
Brightness Control Input. The voltage applied to CTRL controls LED brightness. Varying the voltage
from 0.24V to 1.65V (1.72V for the MAX8596Z) adjusts the brightness from dim to 100% brightness,
respectively. Any voltage above 1.65V (1.72V) does not increase brightness. Hold CTRL below
100mV to shut down the IC after an 8.2ms delay.
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 ceramic capacitor (C
stabilizes the converter, controls soft-start, and lowpass filters direct PWM dimming at CTRL. C
discharges to 0V through an internal 20kΩ resistor in shutdown.
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. Connect LX to the node between the inductor and the Schottky diode. LX is
high impedance in shutdown.
Exposed Pad. Connect to a large ground plane for maximum package heat dissipation. Connect
directly to GND and PGND under the IC.
20ms/div
LED
= 25mA, L = 22µH, C
OUT
drops below 32V (typ), then the IC re-enters soft-start. Connect a 0.1µF ceramic capacitor
MAX8595Z toc07
Typical Operating Characteristics (continued)
0
0
0
0
1V/div
100mA/div
40mA/div
10V/div
IN
CTRL
OUT
= 2.2µF, C
is greater than 34V (typ), the internal n-channel MOSFET turns off
/ 5 or 0.330V (0.343V for the MAX8596Z), whichever is lower.
OUT
OUT
is one diode drop below V
= 0.1µF, C
V
FUNCTION
V
CTRL
I
OUT
V
LED
IN
DIRECT-PWM DIMMING RESPONSE
COMP
COMP
= 0.1µF, R
10µs/div
) from COMP to GND. C
IN
.
SENSE
Pin Description
MAX8595Z toc08
= 13Ω, 4 LEDs,
0
0
0
0
2V/div
32kHz 50%
DUTY CYCLE
10mA/div
20mV/div
AC-COUPLED
500mV/div
AC-COUPLED
COMP
COMP
5