MAX1838EEE Maxim Integrated, MAX1838EEE Datasheet - Page 8

• Manufacturer Part Number: MAX1838EEE
• Description: Power Switch ICs - USB Dual USB Switch w/Fault Blank
• Manufacturer: Maxim Integrated

Specifications of MAX1838EEE

• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Package / Case: QSOP-16
• Mounting Style: SMD/SMT

The MAX1838 is a dual, current-limited switch with
auxiliary inputs designed for USB applications. It has
two independent channels, each with its own fault-
blanking and autoreset function. Each channel has an
error flag output to notify the USB controller when the
current limit, short circuit, undervoltage lockout, or ther-
mal shutdown threshold is reached. A single input
enables both channels. The MAX1838 supplies the out-
puts from one of two inputs, IN or AUX, selected by
SEL (Table 1).
Dual USB Switch with Fault Blanking
and Autoreset
Figure 1. Simplified Functional Diagram
8
_______________________________________________________________________________________
PIN
15
16
SEL
AUX
IN
ON
SHUTDOWN A
THERMAL
SHUTDOWN B
IC POWER
THERMAL
FAULTA
NAME
ADJA
Detailed Description
BLANKING
BLANKING
CHANNEL B CONTROL
CHANNEL A CONTROL
20ms
20ms
Current-Limit Adjust for Channel A. When operating from auxiliary input, adjust the current limit by
connecting a resistor from ADJA to GND as shown in Programmable Current Limit.
Fault Indicator Output for Channel A. This open-drain output goes low when channel A is in
thermal shutdown or undervoltage lockout or in a sustained (>20ms) current-limit or short-circuit
condition.
FAULT LOGIC
CIRCUITRY
CIRCUITRY
FAULT LOGIC
FAULTA
N
N
FAULTB
OUTA1
OUTA2
OUTB2
OUTB1
ADJA
ADJB
The MAX1838 operates from 4V to 5.5V input voltage
range and guarantees a 500mA (min) output current. A
0.9A built-in current limit limits the current in the event
of a heavy overload condition. When powering the
switches from the auxiliary input, each channel has an
adjustable current limit. The MAX1838 has independent
thermal shutdown for each channel in the event of a
prolonged overload or short-circuit condition. The
autoreset function monitors the overload and automati-
cally turns the switch on when the overload is removed.
Use of internal, low-R
MAX1838 to provide four switches in the small 16-pin
QSOP package. Internal micropower charge pumps
generate the gate drive of these high-side switches.
Separate current limiting and thermal shutdown circuits
permit each switch to operate independently, improv-
ing system robustness.
The MAX1838 operates in one of three modes (Table 1).
The device receives its supply current from the AUX
input. When V
lockout voltage, the MAX1838 shuts down to prevent
erroneous switch operation.
Table 1. MAX1838 Operation Modes
Power from IN
Power from AUX
Full Shutdown
(SEL high)
(SEL low)
(ON high)
FUNCTION
Pin Description (continued)
Input Voltage Requirements and
AUX_
falls below the 3.8V undervoltage
ON
Both A and B outputs receive
current from IN. The IC is powered
from AUX.
Both A and B outputs receive
current from AUX. The IC is
powered from AUX. V
to zero in this mode.
Both A and B outputs are open and
no power is available. Either V
V
AUX_
NMOS switches enables the
Undervoltage Lockout
may drop to zero.
IN_
may drop
IN_
or