MAX8804Y Maxim Integrated Products, MAX8804Y Datasheet - Page 12

• Manufacturer Part Number: MAX8804Y
• Description: USB/AC Adapter Chargers
• Manufacturer: Maxim Integrated Products

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The soft-start circuitry activates when entering fast-
charge mode. In the MAX8804Y, soft-start is entered
directly after being enabled, and the charging current
ramps up in 250µs from 0 to 500mA (95mA in USB
mode). This reduces the inrush current on the input
supply. Note that the MAX8804W/MAX8804Z has a pre-
qualification state and the charging current ramps up
when the prequalification state is complete (V
exceeds 2.5V).
The thermal-regulation loop limits the MAX8804W/
MAX8804Y/MAX8804Z die temperature to +105°C by
reducing the charge current as necessary. This feature
not only protects the ICs from overheating, but also
allows a higher charge current at room temperature
without risking damage to the system.
High-Voltage, Dual-Input, USB/AC
Adapter Chargers in 2mm x 3mm TDFN
Figure 4. USB Charging Current Programming
12
______________________________________________________________________________________
MAX8804Y/
MAX8804Z
MAX8804W
USBPWR
THRESHOLD
CURRENT
TOP-OFF
I
I
USB
POK
SET
CHG
CHG
Thermal Regulation Control
DELAY
0mA
0mA
2ms
t
SOFTSTART
380mA
95mA
t
LOW
Soft-Start
1
380mA
475mA
BAT
2
CHG is an open-drain output that indicates charger sta-
tus. CHG goes low during charge cycles where the
MAX8804W/MAX8804Y/MAX8804Z are in prequalifica-
tion or fast-charge mode. CHG goes high impedance
when the charge current reaches the top-off threshold
for more than 4ms, indicating charging is done. The
CHG status is latched after the top-off threshold is
reached. The latch is reset by toggling the SET input,
recycling input power, or increasing the charging cur-
rent to the top-off threshold plus 57mA (typ).
When the MAX8804W/MAX8804Y/MAX8804Z are used
in conjunction with a microprocessor (µP), connect a
pullup resistor between CHG and the logic I/O voltage
to indicate charge status to the µP. Alternatively, CHG
can sink up to 5mA for an LED charge indicator.
475mA
80mA
95mA
3
Charging-Status Output ( CHG )
380mA
95mA
> 2ms
0mA
0mA