MAX8845ZETC+ Maxim Integrated Products, MAX8845ZETC+ Datasheet - Page 9

• Manufacturer Part Number: MAX8845ZETC+
• Description: IC BATT CHRGR LI+ 28V 12TQFN-EP
• Manufacturer: Maxim Integrated Products

Specifications of MAX8845ZETC+

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 0 V ~ 28 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 12-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

MAX8845W are used in conjunction with a microproces-
sor, a pullup resistor to the logic I/O voltage allows CHG
to indicate charge status to the microprocessor instead
of driving an LED.
The thermal-regulation loop limits the MAX8845Z/
MAX8845Y/MAX8845X/MAX8845W die temperature to
+115°C by reducing the charge current as necessary.
This feature not only protects the IC from overheating,
but also allows a higher charge current without risking
damage to the system.
The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W
contain active-low logic input (EN) used to enable the
chargers. Drive EN low, leave unconnected, or connect
to GND to enable the charge-control circuitry. Drive EN
high to disable the charger-control circuitry. EN has an
internal 200kΩ pulldown resistor.
The soft-start algorithm activates when entering fast-
charge mode. When the prequalification state is com-
plete (V
ramps up in 250µs to the full charging current. This
reduces the inrush current demand on the input supply.
Table 1. Autobooting Output States
Note: Present indicates that V
Table 2. CHG States
X = Don’t care.
* I
FAST-CHARGE
High
Low
Low
Low
Low
EN
28V Linear Li+ Battery Chargers with Battery
High
High
Low
Low
Low
ABI
Detection and Overvoltage Protected Output
BATT
4.25V (4.4V for MAX8845W only) ≤ V
4.25V (4.4V for MAX8845W only) ≤ V
4.25V (4.4V for MAX8845W only) ≤ V
is reduced as necessary to prevent the die temperature from exceeding +115°C.
exceeds +2.5V), the charging current
_______________________________________________________________________________________
Not present
Present
Present
Present
Present
BATT
BATT
> 7.5V
Charger Enable Input
V
X
X
IN
Thermal Regulation
≥ 2V and Not Present indicates that the battery is not connected.
High-Z
High-Z
POK
Low
Low
Low
IN
IN
IN
Soft-Start
≤ 7.5V
≤ 7.5V
≤ 7.5V
CHARGER STATE
Fast-charge/top-off
Fast-charge/top-off
MAX8845W only)
4.2V (4.35V for
CC/CV mode
> V
Shutdown
Shutdown
V
< 2.4V
IN
≥ 2.5V
BATT
The maximum charging current is programmed by an
external resistor connected from SETI to GND (R
Use the following equation to determine the fast-charge
current (I
where I
R
tinuous charging current limit of 1A
The top-off current threshold is programmed by an
external resistor connected from MIN to GND (R
Use the following equation to determine the top-off cur-
rent (I
where I
2.2kΩ.
X
X
- 30mV
SETI
MIN
must always be 1.4kΩ or higher due to the con-
FAST_CHARGE
MIN
I
MIN
I
FAST_CHARGE
):
MIN
Top-Off Current Threshold Setting
is in mA and R
(falling) = 148V/R
100% of I
10% of I
(rising) = 295V/R
Applications Information
I
FAST CHARGE
(MAX8845Z)
Fast Charge-Current Setting
ABO
High
High
High
High
< I
Low
I
FAST-CHARGE
BATT
FAST-CHARGE
_
is in amps and R
0
0
):
MIN
MIN
MIN
MIN
=
*
*
1400
is in kΩ. Use R
MAX8845X/MAX8845W)
R
(kΩ) + 22mA
(kΩ) - 24mA
RMS
SETI
High-Z
High-Z
High-Z
CHG
Low
Low
V
(MAX8845Y/
.
SETI
High-Z
High-Z
High-Z
ABO
Low
Low
is in ohms.
Fast-charge
Precharge
Shutdown
Disabled
STATE
Top-off
MIN
SETI
MIN
9
).
).
≤