LTC4075HVXEDD#TRPBF Linear Technology, LTC4075HVXEDD#TRPBF Datasheet - Page 9

• Manufacturer Part Number: LTC4075HVXEDD#TRPBF
• Description: IC CHARGER LI-ION 10-DFN
• Manufacturer: Linear Technology

Specifications of LTC4075HVXEDD#TRPBF

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 4.3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-WFDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

OPERATION
The LTC4075HVX is designed to effi ciently manage charg-
ing of a single-cell lithium-ion battery from two separate
power sources: a wall adapter and USB power bus. Us-
ing the constant-current/constant-voltage algorithm, the
charger can deliver up to 950mA of charge current from
the wall adapter supply or up to 850mA of charge current
from the USB supply with a fi nal fl oat voltage accuracy of
±0.6%. The LTC4075HVX has two internal P-channel power
MOSFETs and thermal regulation circuitry. No blocking
diodes or external sense resistors are required.
Power Source Selection
The LTC4075HVX can charge a battery from either the wall
adapter input or the USB port input. The LTC4075HVX au-
tomatically senses the presence of voltage at each input. If
both power sources are present, the LTC4075HVX defaults
to the wall adapter source provided a valid voltage is pres-
ent at the DCIN input. “Valid voltage” is defi ned as:
• Supply voltage is greater than the undervoltage lock-
• Supply voltage is greater than the battery voltage by
The open drain power status outputs ( ⎯ P ⎯ W ⎯ R and USBPWR)
indicate which power source has been selected. Table 1
describes the behavior of these status outputs.
Programming and Monitoring Charge Current
The charge current delivered to the battery from the wall
adapter or USB supply is programmed using a single re-
sistor from the IDC or IUSB pin to ground. Both program
resistors and charge currents (I
the following equations:
out threshold and less than the overvoltage lockout
threshold.
40mV.
R
R
IDC
IUSB
=
=
I
CHRG DC
I
1000
CHRG USB
1 1 000
−
V
−
V
,
I
CHRG DC
,
I
CHRG USB
−
−
=
CHRG
1000
R
=
IDC
) are calculated using
1000
R
V
IUSB
V
Charge current out of the BAT pin can be determined at
any time by monitoring the IDC or IUSB pin voltage and
applying the following equations:
Programming Charge Termination
The charge cycle terminates when the charge current
falls below the programmed termination threshold level
during constant-voltage mode. This threshold is set by
connecting an external resistor, R
pin to ground. The charge termination current threshold
(I
The termination condition is detected by using an internal
fi ltered comparator to monitor the ITERM pin. When the
ITERM pin voltage drops below 100mV* for longer than
t
charge current is latched off and the LTC4075HVX enters
standby mode.
When charging, transient loads on the BAT pin can cause
the ITERM pin to fall below 100mV for short periods of
time before the DC charge current has dropped below the
programmed termination current. The 1.6ms fi lter time
(t
transient loads of this nature do not result in premature
charge cycle termination. Once the average charge cur-
rent drops below the programmed termination threshold,
the LTC4075HVX terminates the charge cycle and stops
providing current out of the BAT pin. In this state, any load
on the BAT pin must be supplied by the battery.
*Any external sources that hold the ITERM pin above 100mV will prevent the LTC4075HVX from
terminating a charge cycle.
TERMINATE
TERMINATE
TERMINATE
I
I
R
BAT
BAT
ITERM
=
=
R
R
V
V
=
IDC
IUSB
(typically 1.6ms), charging is terminated. The
IDC
IUSB
) is set by the following equation:
) on the termination comparator ensures that
I
TERMINATE
•
100
•
1000
1000
V
, ( arg
, ( arg
ch
,
ch
I
TERMINATE
ing from wall adapter
LTC4075HVX
ing from USB
ITERM
=
R
, from the ITERM
100
ITERM
V
sup
p
l l y)
) )
4075hvxf
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