MAX4978 Datasheet, PDF (1/10 Pages) Maxim Integrated Products – Overvoltage Protector with Active Current Limit

19-4137; Rev 0; 5/08
Overvoltage Protector with
Active Current Limit
General Description
The MAX4978–MAX4981 overvoltage-protection devices
protect low-voltage systems against voltage faults up to
+28V and feature a low 85mΩ R_ON FET, an active cur-
rent limiter, and lithium-ion battery overcharge protec-
tion (MAX4980/MAX4981). These devices are used to
protect the charger input port on a portable device.
The overvoltage protector feature protects against volt-
ages up to 28V with two different trip thresholds: 5.7V
(MAX4978/MAX4980/MAX4981) and 6.8V (MAX4979).
There is an undervoltage protector with two different trip
thresholds: 4.4V (MAX4978) and 2.63V (MAX4979/
MAX4980/MAX4981).
The overcurrent limiter and battery voltage monitor fea-
tures provide a second layer of protection for a lithium-
ion battery charger. The overcurrent limiter is available
in two different thresholds: 0.9A (MAX4978/MAX4979/
MAX4980) and 1.95A (MAX4981). Once current reach-
es the threshold, it is held for a 20ms blanking time. If
the current is still at the limit after the blanking time, the
FET is turned off, and the device restarts the cycle after
160ms. The battery voltage monitor measures the volt-
age of a lithium-ion battery and disables the FET if the
battery voltage reaches 4.4V (MAX4980/MAX4981).
The MAX4978–MAX4981 are available in a small 8-pin
TDFN (2mm x 3mm) package and are specified over
the extended -40°C to +85°C temperature range.
Applications
Cell Phones
MP3 Players
Digital Still Cameras
PDAs and Palmtop
Devices
Typical Application Circuit appears at end of data sheet.
Features
♦ Input Voltage Protection Up to +28V
♦ Integrated nFET Switch, 85mΩ (typ)
♦ Preset Overvoltage Protection Trip Level
5.7V (typ) (MAX4978/MAX4980/MAX4981)
6.8V (typ) (MAX4979)
♦ Low-Current Undervoltage Lockout Mode
♦ Overcurrent Protection
♦ Internal 160ms (typ) Startup Delay
♦ Thermal-Shutdown Protection
♦ Battery Overcharge Protection
(MAX4980/MAX4981)
♦ Startup Debounce Time Indicator
(MAX4978/MAX4979)
♦ Small, 8-Pin (2mm x 3mm) TDFN Package
Pin Configuration
TOP VIEW
OUT I.C.
87
I.C. GND
65
MAX4978
MAX4979
MAX4980
MAX4981
*EP
1 234
IN SDT(BAT) I.C. EN
TDFN-EP
(BAT) IS FOR MAX4980/MAX4981 ONLY.
*EP = EXPOSED PAD. CONNECT EP TO GND.
Ordering Information/Selector Guide
PART
PIN-PACKAGE
CURRENT
LIMIT (mA)
BATTERY
MONITOR
UVLO
(V)
OVLO
(V)
TOP
MARK
PKG
CODE
MAX4978ETA+
8 TDFN-EP*
900
No
4.4
MAX4979ETA+**
8 TDFN-EP*
900
No
2.63
MAX4980ETA+
8 TDFN-EP*
900
Yes
2.63
MAX4981ETA+
8 TDFN-EP*
1950
Yes
2.63
Note: All devices specified over the -40°C to +85°C operating temperature range.
+Denotes a lead-free package.
*EP = Exposed pad.
**Future product—contact factory for availability.
5.7
AAK
T823-1
6.8
AAL
T823-1
5.7
AAM
T823-1
5.7
AAN
T823-1
________________________________________________________________ Maxim Integrated Products 1
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or visit Maxim’s website at www.maxim-ic.com.