Rainbow Electronics MAX8575 - Manual (Page 5)

MAX8570–MAX8575
High-Efficiency LCD Boost
with True Shutdown
_______________________________________________________________________________________ 5
PIN NAME FUNCTION
FB
(MAX8570/
MAX8571/
MAX8574)
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
(MAX8572/
MAX8573/
MAX8575)
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 7.5M
Ω resistor.
2 GND Ground
3 SHDN
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.
4 LX Inductor Switching Connection
5 SW
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.
6 V 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
100 µs/div
V OUT
I OUT
100mV/div
(AC-COUPLED)
5mA/div
0
STARTUP AND SHUTDOWN WAVEFORMS
MAX8570/71/73/74/75 toc16
400 µs/div
V
OUT
I LX
5V/div
10V/div
200mA/div
1.8 Ω 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.)