Datasheet

MAX8570–MAX8575
High-Efficiency LCD Boost
with True Shutdown
_______________________________________________________________________________________ 5
PIN
MAX8570
(µDFN)
MAX8570/
MAX8571/
MAX8574
(SOT23)
MAX8572/
MAX8573/
MAX8575
(SOT23)
NAME FUNCTION
31—FB
Feedback for Setting the Output Voltage. Connect FB to the center of a resistor
voltage-divider from the output to GND to set positive output voltages.
— — 1 OUT
Output. The output voltage is preset to 15V. Connect a 1µF ceramic capacitor
from OUT to GND. In shutdown, OUT is pulled to GND by an internal 7.5MΩ
resistor.
2 2 2 GND Ground
133SHDN
Shutdown Input. A logic-low at SHDN places the part in low-power shutdown
mode. Pull SHDN high or connect to V
CC
for normal operation.
6 4 4 LX Inductor Switching Connection
555SW
Isolation Switch Output. Internally connected to the drain of a p-channel
MOSFET used to isolate the output from the input during shutdown. Connect a
4.7µF ceramic capacitor from SW to GND. If True Shutdown is not required, SW
can be left open with the input supply connected directly to the inductor.
466V
CC
Input Voltage Supply. Connect a 2.7V to 5.5V input supply to V
CC
. Connect a
1µF ceramic capacitor from V
CC
to GND.
Pin Description
LOAD TRANSIENT
MAX8570/71/73/74/75 toc15
100µs/div
V
OUT
I
OUT
100mV/div
(AC-COUPLED)
5mA/div
0
STARTUP AND SHUTDOWN WAVEFORMS
MAX8570/71/73/74/75 toc16
400µs/div
V
OUT
I
LX
5V/div
10V/div
200mA/div
1.8Ω LOAD
0
0
V
SHDN
BOOST SOFT-START
SW TURN-ON
Typical Operating Characteristics (continued)
(MAX8571, V
CC
= 3.6V, V
OUT
= 18V, Circuit of Figure 2, T
A
= +25°C, unless otherwise noted.)