MAX8903CETI+ Maxim Integrated Products, MAX8903CETI+ Datasheet - Page 18

• Manufacturer Part Number: MAX8903CETI+
• Description: IC DC/DC CHARGER LI+ 2A 28-TQFN
• Manufacturer: Maxim Integrated Products
• Series: Smart Power Selector™r

Specifications of MAX8903CETI+

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 4.1 V ~ 16 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2A 1-Cell Li+ DC-DC Chargers for USB
and Adapter Power
USB to SYS powers the system and charges the bat-
tery. If the battery is greater than the minimum system
voltage, the SYS voltage is connected to the battery.
The USB input then supplies the SYS load and charges
the battery with any extra available current, while not
exceeding the maximum-allowed USB current. Load
transients can be absorbed by the battery while mini-
mizing the voltage disturbance on SYS. When battery
charging is completed, or the charger is disabled, SYS
is regulated to V
valid, power is only taken from the DC input.
Driving USUS high and DCM low turns off charging as
well as the SYS output and reduces input current to
170μA to accommodate USB suspend mode. See
Table 2 for settings.
When CEN is low, the charger is on. When CEN is high,
the charger turns off. CEN does not affect the SYS out-
Table 2. Input Limiter Control Logic
** Charge current cannot exceed the input current limit. Charge may be less than the maximum charge current if the total SYS load
exceeds the input current limit.
*** There is an internal diode from DCM (anode) to DC (cathode) as shown in Figure 1. If the DCM level needs to be set by a μP, use
a MOSFET for isolation as shown in FIgure 3.
X = Don’t care.
18
AC Adapter at DC Input
USB Power at DC Input
USB Power at USB Input,
DC Unconnected
DC and USB Unconnected
______________________________________________________________________________________
POWER SOURCE
SYSREG
. If both USB and DC inputs are
DOK
Charge Enable ( CEN )
H
H
H
H
L
L
L
L
UOK
X
X
X
X
H
L
L
L
USB Suspend
DCM*** IUSB USUS
H
X
X
X
X
L
L
L
H
H
X
L
X
L
X
X
H
H
X
L
L
L
L
X
put. In many systems, there is no need for the system
controller (typically a microprocessor) to disable the
charger, because the MAX8903_ smart power selector
circuitry independently manages charging and
adapter/battery power hand-off. In these situations, CEN
may be connected to ground.
To prevent input transients that can cause instability in
the USB or AC adapter power source, the rate of change
of the input current and charge current is limited. When
an input source is valid, SYS current is ramped from
zero to the set current-limit value in typically 50μs. This
also means that if DC becomes valid after USB, the
SYS current limit is ramped down to zero before switch-
ing from the USB to DC input. At some point, SYS is no
longer able to support the load and may switch over to
BAT. The switchover to BAT occurs when V
This threshold is a function of the SYS capacitor size
and SYS load. The SYS current limit then ramps from
zero to the set current level and SYS supports the load
DC STEP-DOWN
CURRENT LIMIT
USB suspend
No DC input
6000V/R
OUTPUT
100mA
500mA
IDC
USB input off. DC
CURRENT LIMIT
input has priority.
USB suspend
No USB input
USB INPUT
100mA
500mA
1200V/R
1200V/R
1200V/R
1200V/R
1200V/R
CURRENT**
6000V/R
MAXIMUM
Soft-Start
CHARGE
SYS
Lesser of
Lesser of
Lesser of
Lesser of
Lesser of
100mA
500mA
100mA
500mA
0
0
0
ISET
ISET
ISET
ISET
ISET
< V
IDC
BAT
and
and
and
and
and
.