Rainbow Electronics MAX1558H - Manual (Page 7)

Detailed Description
The MAX1558/MAX1558H are dual current-limited
switches designed for USB applications. They have two
independent switches, each with its own enable control
input and autoreset function. Each switch has an error-
flag output to notify the USB controller when current-
limit, short-circuit, undervoltage-lockout, or thermal-
shutdown conditions occur (Figure 2). The MAX1558/
MAX1558H operate from a 2.7V to 5.5V supply. Each
output can supply up to 1.2A. Current limit for both
channels is set with one external resistor.
The MAX1558/MAX1558H have independent thermal
shutdown for each switch in the event of a prolonged
overload. An autoreset function monitors the output and
automatically turns the switch on when the overload is
removed. Separate current limiting and thermal-shut-
down circuits permit each switch to operate indepen-
dently, improving system robustness.
MAX1558/MAX1558H
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
_______________________________________________________________________________________ 7
PIN NAME FUNCTION
1 INA
Power Input for OUTA. Connect INA and INB together and bypass with a 0.1µF capacitor to ground.
Load conditions may require additional bulk capacitance to prevent the input from being pulled down.
2
ONA
*(ONA)
Control Input for Switch A. Can be driven higher than IN_ without damage. A logic low turns switch A on
for the MAX1558. A logic high turns switch A on for the MAX1558H.
3 ISET
Current-Limit Adjust for Both Channels. Connect a resistor between 26k Ω to 60kΩ from ISET to ground to
program the current limit. See Setting the Current Limit in the Applications Information section.
4
ONB
*(ONB)
Control Input for Switch B. Can be driven higher than IN_ without damage. A logic low turns switch B on
for the MAX1558. A logic high turns switch B on for the MAX1558H.
5 INB
Power Input for OUTB. Connect INB and INA together and bypass with a 0.1µF capacitor to ground.
Load conditions may require additional bulk capacitance to prevent the input from being pulled down.
6 OUTB
Power Output for Switch B. Connect a 1µF capacitor from OUTB to ground. The load condition may
require additional bulk capacitance.
7 FLTB
Fault Indicator Output for Switch B. This open-drain output goes low when switch B is in thermal
shutdown or UVLO or in a sustained (>20ms) current-limit or short-circuit condition.
8 GND Ground
9 FLTA
Fault Indicator Output for Switch A. This open-drain output goes low when switch A is in thermal
shutdown or UVLO or in a sustained (>20ms) current-limit or short-circuit condition.
10 OUTA
Power Output for Switch A. Connect a 1µF capacitor from OUTA to ground. The load condition may
require additional bulk capacitance.
— PAD
Exposed Pad, Internally Connected to GND. Connect exposed pad to a large copper trace for maximum
power dissipation.
Pin Description
*( ) are for the MAX1558H only.
MAX1558
INPUT
2.7V TO 5.5V
INA
INB
ISET
FLTA
FLTB
ONA
ONB
ONA
ONB
OUTA
OUTB
GND
USB
PORT A
USB
PORT B
0.1 µF
100k Ω
100k Ω
1 µF*
1 µF*
*USB APPLICATIONS MAY REQUIRE ADDITIONAL
BULK CAPACITANCE
Figure 1. Typical Application Circuit