MCP73871-2AAI/SS Microchip Technology, MCP73871-2AAI/SS Datasheet - Page 14

• Manufacturer Part Number: MCP73871-2AAI/SS
• Description: USB/AC Battery Charger With Power Path Management 20 SSOP .209in TUBE
• Manufacturer: Microchip Technology

Specifications of MCP73871-2AAI/SS

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

MCP73871
The voltage divider equation is shown below:
The calculated R
selected for R
to build the voltage divider for VPCC.
FIGURE 3-1:
3.4
The input source type selection (SEL) pin is used to
select input power source for input current limit control
feature. With the SEL input High, the MCP73871
device is designed to provide a typical 1.65A to system
power and charge Li-Ion battery from a regular 5V wall
adapter. The MCP73871 device limits the input current
up to 1.8A. When SEL active Low, the input source is
designed to provide system power and Li-Ion battery
charging from a USB Port input while adhering to the
current limits governed by the USB specification.
3.5
Connect to negative terminal of battery, system load
and input supply.
3.6
Connect to positive terminal of Li-Ion / Li-Polymer
batteries. Bypass to V
ensure loop stability when the battery is disconnected.
3.7
Connect to positive terminal of battery. A precision
internal voltage sense regulates the final voltage on
this pin to V
DS22090A-page 14
Input Source Type Selection (SEL)
Battery Management 0V Reference
(V
Battery Charge Control Output
(V
Battery Voltage Sense
(V
V
VPCC
SS
BAT
BAT_SENSE
REG
1.23V
2
330 kΩ
110 kΩ
)
. The 330 kΩ resistor is selected for R
.
)
1
=
R
equals to 337.2 kΩ when 110 kΩ is
=
1
⎛
⎝
------------------ -
R
=
V
⎛
⎝
SS
Voltage Divider Example.
1
----------------------------- -
110k
IN
R
+
337.2kΩ
)
2
with a minimum of 4.7 µF to
110k
R
2
Ω
⎞
⎠
×
+
Ω
V
R
IN
VPCC
1
⎞
⎠
=
×
5V
1.23V
1
3.8
The maximum constant charge current is set by placing
a resistor from PROG1 to V
mum constant charge current for both ac-dc adapter
and USB port. However, the actual charge current is
based on input source type and system load require-
ment.
3.9
The MCP73871 device USB-Port current regulation set
input (PROG2) is a digital input selection. A logic Low
selects a 1 unit load input current from USB port
(100 mA); a logic High selects a 5 unit loads input cur-
rent from USB port (500 mA).
3.10
STAT1 is an open-drain logic output for connection to
an LED for charge status indication. Alternatively, a
pull-up resistor can be applied for interfacing to a host
microcontroller. Refer to
status output during a charge cycle.
3.11
STAT2 is an open-drain logic output for connection to
an LED for charge status indication. Alternatively, a
pull-up resistor can be applied for interfacing to a host
microcontroller. Refer to
status output during a charge cycle.
3.12
The power-good (PG) is an open-drain logic output for
input power supply indication. The PG output is low
whenever the input to the MCP73871 device is above
the UVLO threshold and greater than the battery volt-
age. The PG output can be used as an indication to the
user via an illuminated LED or to the system via a pull-
up resistor for interfacing to a host microcontroller that
an input source other than the battery is supplying
power. Refer to
output during a charge cycle.
3.13
STAT1 also serves as low battery output (LBO) if the
selected MCP73871 is equipped with this feature. It
reminds the system or end user when the Li-Ion battery
voltage level is low. The LBO feature enables when the
system is running from the Li-Ion batteries. The LBO
indicator can be used as an indication to the user via lit
up LED or to the system via a pull-up resistor for inter-
facing to a host microcontroller that an input source
other than the battery is supplying power. Refer to
Table 5-1
charge cycle.
Charge Current Regulation Set
(PROG1)
USB-Port Current Regulation Set
(PROG2)
Charge Status Output 1 (STAT1)
Charge Status Output 2 (STAT2)
Power-Good (PG)
Low Battery Output (LBO)
for a summary of the status output during a
Table 5-1
© 2008 Microchip Technology Inc.
Table 5-1
Table 5-1
for a summary of the status
SS
. PROG1 sets the maxi-
for a summary of the
for a summary of the