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MAX8844ZETD+T

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17
MAX8844Z/MAX8844Y
28V Dual Input Linear Li+ Battery Chargers with
Battery Detection and Overvoltage-Protected Output
_______________________________________________________________________________________ 7
Pin Description
PIN
MAX8844Z MAX8844Y
NAME FUNCTION
11IN
Input Supply Voltage. IN is the power supply for the SAFEOUT linear regulator and the
battery charger. See the DC and USB Power Supplies section. Bypass IN to GND with a
1µF or larger ceramic capacitor to improve line noise and input transient rejection.
22POK
Active-Low, Input Voltage Status Indicator. POK is an open-drain output that asserts low
when 2.35V < (V
IN
or V
USB
) < 7V and [(V
IN
or V
USB
) - V
BATT
] > 40mV. If (V
IN
or V
USB
) >
+7.5V or V
BATT
> (V
IN
or V
USB
), the IC is shut down and POK becomes high impedance.
Connect a pullup resistor to the microprocessor’s I/O voltage when interfacing with a
microprocessor logic input.
3 3 USB
USB Input Supply Voltage. USB is the power supply for the SAFEUSB linear regulator
and the battery charger. See the DC and USB Power Supplies section. Bypass USB to
GND with a 1µF or larger ceramic capacitor to improve line noise and input transient
rejection.
4 4 ABI
Autobooting External Input. See the Autobooting Assistant section and Table 1 for
autobooting conditions. ABI is pulled to GND through an internal 200kΩ resistor.
5 — ABO
Active-High, Autobooting Logic Output. See the Autobooting Assistant section and Table
1 for autobooting conditions.
—5ABO
Active-Low, Autobooting Logic Output. See the Autobooting Assistant section and Table
1 for autobooting conditions.
6 6 MIN
Top-Off Current Threshold Programmable Input. I
MIN
(mA) falling = 126V/R
MIN
(kΩ) + 27
(mA).
7 7 SETI
Charge-Current Program and Fast-Charge Current Monitor. Output current from SETI is
1120µA per ampere of battery charging current. Set the charging current by connecting
a resistor (R
SETI
in Figure 3) from SETI to GND. I
FAST-CHARGE
= 1250V/R
SETI
. To
configure the MAX8844Z/MAX8844Y as a USB charger, see Figure 5.
8 8 DETBAT
Battery Pack ID Resistor Detection Input. If DETBAT is pulled low through a pulldown
resistor less than 51kΩ, the charger is enabled. If DETBAT is left unconnected, the
charger is disabled.
99CHG
Active-Low, Charging Indicator. CHG is an open-drain output that is pulled low once
charging begins. CHG is high impedance when the battery current drops below MIN, or
when the IC is disabled. Connect a pullup resistor to the microprocessor’s I/O voltage
when interfacing with a microprocessor logic input.
10 10 EN
Active-Low, Logic-Level Enable Input. Drive EN high to disable charger. Drive EN low or
leave unconnected for normal operation. EN has an internal 200kΩ pulldown resistor.
11 11 GND
Ground. Connect GND and the exposed pad to a large copper ground plane for
maximum power dissipation. Connect GND to the exposed pad directly under the IC.
12 12 BATT Li+ Battery Connection. Bypass BATT to GND with a 2.2µF ceramic capacitor.
13 13 SAFEUSB
4.7V Regulated LDO Output with Input Overvoltage Protection. Bypass SAFEUSB to
GND with a 1µF or larger ceramic capacitor. SAFEUSB can be used to supply low-
voltage-rated USB systems.
MAX8844Z/MAX8844Y
28V Dual Input Linear Li+ Battery Chargers with
Battery Detection and Overvoltage-Protected Output
8 _______________________________________________________________________________________
OUTPUT DRIVER,
CURRENT SENSE,
AND LOGIC
TEMPERATURE
SENSOR
V
L
REGULATOR
REF
REFOK
V
IN
/V
USB
*
OVLO
V
L
UVLO
V
REF
V
REF
LOGIC
BATT
DETBAT
ABI
EN
POK
IN/USB*
BATT
IN
BATT
POK
200kΩ
GND
EP
+115°C
4.2V
Li+
V
I/O
200kΩ
CHG
MAX8844Z
MAX8844Y
V
L
V
REF
I
MINREF
DETBAT
LINEAR
REGULATOR
WITH OVP
SETI
MIN
SAFEOUT
LINEAR
REGULATOR
WITH OVP
SAFEUSB
USB
*SEE THE
DC AND USB
POWER SUPPLIES
SECTION.
ABO (MAX8844Z ONLY)
ABO (MAX8844Y ONLY)
Figure 1. Functional Diagram
Pin Description (continued)
PIN
MAX8844Z MAX8844Y
NAME FUNCTION
14 14 SAFEOUT
4.7V Regulated LDO Output with Input Overvoltage Protection. Bypass SAFEOUT to
GND with a 1µF or larger ceramic capacitor. SAFEOUT can be used to supply low-
voltage-rated charging systems.
——EP
Exposed Pad. Connect the exposed pad to a large ground plane for maximum power
dissipation. Connect GND to the exposed pad directly under the IC.
Detailed Description
The MAX8844Z/MAX8844Y chargers use voltage, cur-
rent, and thermal-control loops to charge a single Li+
cell and protect the battery (Figure 1). When a Li+ bat-
tery with a cell voltage below 2.5V is inserted, the
MAX8844Z/MAX8844Y chargers enter a prequalifica-
tion stage where they precharge that cell with 10% of
the user-programmed fast-charge current (Figure 2).
The CHG indicator is driven low to indicate entry into
the prequalification state. When the battery voltage
exceeds 2.5V, the charger soft-starts as it enters the
fast-charge stage. The fast-charge current level is pro-
grammed through a resistor from SETI to GND. As the
battery voltage approaches 4.2V, the battery current is
reduced. If the battery current drops to less than the
top-off current threshold set by R
MIN
, the charger
enters top-off mode and the CHG indicator goes high
impedance, signaling that the battery is fully charged.
Overvoltage-Protected Output (SAFEOUT)
SAFEOUT is a linear regulator that provides an output
voltage of 4.7V and can be used to supply low-voltage-
rated charging systems. The SAFEOUT linear regulator
turns on when V
IN
≥ 4.25V regardless of EN and is dis-
abled when V
IN
is greater than the overvoltage thresh-
old (7.5V typ).
Overvoltage Protected Output (SAFEUSB)
SAFEUSB is a linear regulator that provides an output
voltage of 4.7V and can be used to supply low voltage
rated USB systems. The SAFEUSB linear regulator
turns on when V
USB
≥ 4.25V regardless of EN and is
disabled when V
USB
is greater than the overvoltage
threshold (7.5V typ).
Battery Pack Detection Input (DETBAT)
DETBAT is a battery pack ID resistor detector that
enables the battery charger if pulled low through a
resistor that is less than 51kΩ. If DETBAT is left uncon-
nected or the pulldown resistor is 51kΩ or greater, the
battery charger is disabled.
POK
Output
The open-drain POK output asserts low when 2.35V ≤
(V
IN
or V
USB
) ≤ 7V, [(V
IN
or V
USB
) - V
BATT
] ≥ 40mV
(typ V
IN
or V
USB
rising), and DETBET is pulled low
through a resistor that is less than 51kΩ. POK is high
MAX8844Z/MAX8844Y
28V Dual Input Linear Li+ Battery Chargers with
Battery Detection and Overvoltage-Protected Output
_______________________________________________________________________________________ 9
V
BATT
< 2.5V
PRECHARGE
10% OF I
FAST-CHARGE
CHG = LOW
FAST-CHARGE
CONSTANT-CURRENT CHARGE
100% OF I
FAST-CHARGE
CHG = LOW
TOP-OFF
4.2 VOLTAGE REGULATION
CHG = HIGH-Z
(V
IN
*
- V
BATT
) < 30mV
V
BATT
< 2.4V
V
BATT
≥ 2.5V
V
IN
*
< 7.5V, AND
(V
IN
*
- V
BATT
) ≥ 40mV, AND
IC ENABLED
SHUTDOWN
CHARGER = DISABLED
CHG = HIGH-Z
V
IN
*
> 7V, OR
(V
IN
*
- V
BATT
) < 30mV, OR
IC DISABLED
ASYNCHRONOUS
FROM ANYWHERE
V
IN
*
> 7.5V, OR
(V
IN
*
- V
BATT
) < 30mV, OR
THERMAL SHUTDOWN, OR
IC DISABLED
I
BATT
> 248V/R
MIN
(kΩ) - 16mA
I
BATT
≤ I
MIN
FOR 6.2ms (typ) OR LONGER
CHARGING CURRENT REDUCTION
CHARGING CURRENT IS REDUCED
AS NECESSARY
DIE TEMPERATURE > +115°C
ANY CHARGING STATE
RETURN TO
CHARGING STATE
DIE TEMPERATURE ≤ +115°C
*SEE THE
DC AND USB
POWER SUPPLIES
SECTION.
Figure 2. Charge-State Diagram
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17

MAX8844ZETD+T

Mfr. #:
Buy MAX8844ZETD+T
Manufacturer:
Maxim Integrated
Description:
Battery Management 28V Linear Li+ Battery Charger
Lifecycle:
New from this manufacturer.
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