19-3979; Rev 0; 2/06
Overvoltage-Protection Controllers with
Status FLAG
General Description
Features
The MAX4838A/MAX4840A/MAX4842A are overvoltage-
protection ICs that protect low-voltage systems against
voltages of up to +28V. If the input voltage exceeds the
overvoltage trip level, the MAX4838A/MAX4840A/
MAX4842A turn off the low-cost external n-channel
FET(s) to prevent damage to the protected components.
An internal charge pump eliminates the need for external
capacitors and drives the FET gate for a simple,
robust solution.
♦ Overvoltage Protection Up to +28V
♦ Preset 7.4V, 5.8V, or 4.7V Overvoltage Trip Level
♦ Drives Low-Cost nMOS FET
♦ Internal 50ms Startup Delay
♦ Internal Charge Pump
♦ Undervoltage Lockout
♦ ±±5kV ESD-Protected Input
♦ Voltage Fault FLAG Indicator
♦ 6-Pin SC70 and µDFN Packages
♦ Lead Free
The MAX4838A has a 7.4V overvoltage threshold, and
the MAX4840A has a 5.8V overvoltage threshold. The
MAX4842A has a 4.7V overvoltage threshold. The
MAX4838A/MAX4840A have an undervoltage-lockout
(UVLO) threshold of 3.25V, while the MAX4842A has a
UVLO of 2.5V. In addition to the single FET configura-
tion, the devices can be configured with back-to-back
external FETs to prevent currents from being back-dri-
ven into the adapter.
Ordering Information
PIN-
TOP
PKG
PART
PACKAGE
MARK
CODE
On power-up, the device waits for 50ms before driving
GATE high. FLAG is held low for an additional 50ms
after GATE goes high before deasserting. The
MAX4838A/MAX4840A/MAX4842A have an open-drain
FLAG output. The FLAG output asserts immediately to
an overvoltage fault.
MAX4838AEXT+T
MAX4838AELT+
MAX4840AEXT+T
MAX4840AELT+
MAX4842AEXT+T
MAX4842AELT+*
6 ꢁC70
6 µSFN
6 ꢁC70
6 µSFN
6 ꢁC70
6 µSFN
ACY
KU
X6ꢁ-±
L6±±-±
X6ꢁ-±
L6±±-±
X6ꢁ-±
L6±±-±
ACZ
KV
ASA
KW
Additional features include a ±±5kV (ꢀHM) EꢁS-pro-
tected input (when bypassed with a ±µF capacitor) and
a shutdown pin (EN) to turn off the device.
Note: All devices specified for the -40°C to +85°C extended
All devices are offered in a small 6-pin ꢁC70 and 6-pin
±.5mm x ±.0mm µSFN packages and are specified
over the -40°C to +85°C extended temperature range.
temperature range.
*Future product—contact factory for availability.
+Denotes lead-free package.
Applications
Cell Phones
Typical Operating Circuit
Sigital ꢁtill Cameras
PSAs and Palmtop Sevices
MP3 Players
INPUT
+1.2V TO +28V
OUTPUT
NMOS
1
4
3
IN
GATE
1µF
V
IO
Selector Guide
MAX4838A
MAX4840A
MAX4842A
OV
UVLO
THRESHOLD
(V)
TRIP
LEVEL
(V)
EN
FLAG
6
2
PART
EN
INPUT OUTPUT
FLAG
NOTE: EN AND PULLUP
RESISTOR
GND
MAX4838A
MAX4840A
MAX4842A
3.25
3.25
2.50
7.4
5.8
4.7
Yes Open-Srain
Yes Open-Srain
Yes Open-Srain
Pin Configuration appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products
±
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.