LTC4090EDJC#PBF Linear Technology, LTC4090EDJC#PBF Datasheet - Page 15

• Manufacturer Part Number: LTC4090EDJC#PBF
• Description: IC USB POWER MANAGER 22-DFN
• Manufacturer: Linear Technology

Specifications of LTC4090EDJC#PBF

• Function: Power Management
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 4.35 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 22-WFDFN Exposed Pad
• Supply Voltage Range: 4.35V To 5.5V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: DFN
• No. Of Pins: 22
• Msl: MSL 1 - Unlimited
• Termination Type: SMD
• Supply Voltage Min: 4.35V
• Rohs Compliant: Yes
• Filter Terminals: SMD
• Frequency: 2.7MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

OPERATION
Suspend Mode
When SUSP is pulled above V
enter suspend mode to comply with the USB specifi cation.
In this mode, the power path between IN and OUT is put
in a high impedance state to reduce the IN input current to
50μA. If no other power source is available to drive HVIN,
the system load connected to OUT is supplied through the
ideal diodes connected to BAT.
Battery Charger
The battery charger circuits of the LTC4090/LTC4090-5
are designed for charging single-cell lithium-ion batter-
ies. Featuring an internal P-channel power MOSFET, the
charger uses a constant-current / constant-voltage charge
algorithm with programmable charge current and a pro-
grammable timer for charge termination. Charge current
can be programmed up to 1.5A. The fi nal fl oat voltage ac-
curacy is ±0.8% typical. No blocking diode or sense resistor
is required when powering either the IN or the HVIN pins.
The CHRG open-drain status output provides information
regarding the charging status of the LTC4090/LTC4090-5
at all times. An NTC input provides the option of charge
qualifi cation using battery temperature.
The charge cycle begins when the voltage at the OUT
pin rises above the battery voltage and the battery volt-
age is below the recharge threshold. No charge current
actually fl ows until the OUT voltage is 100mV above
the BAT voltage. At the beginning of the charge cycle, if
the battery voltage is below 2.9V, the charger goes into
I
I
MAX
FWD
Figure 3. LTC4090/LTC4090-5 vs Schottky Diode
Forward Voltage Drop
0
LTC4090/LTC4090-5
V
FWD
SLOPE: 1/R
FORWARD VOLTAGE (V)
SLOPE: 1/R
FWD
DIO(ON)
IH
SCHOTTKY
DIODE
the LTC4090/LTC4090-5
CONSTANT
I
CONSTANT
R
CONSTANT
V
0N
0N
0N
4090 F03
trickle charge mode to bring the cell voltage up to a safe
level for charging. The charger goes into the fast charge
constant-current mode once the voltage on the BAT pin
rises above 2.9V. In constant-current mode, the charge
current is set by R
fi nal fl oat voltage, the charge current begins to decrease
as the LTC4090/LTC4090-5 switch to constant-voltage
mode. When the charge current drops below 10% of the
programmed value while in constant-voltage mode the
CHRG pin assumes a high impedance state.
An external capacitor on the TIMER pin sets the total
minimum charge time. When this time elapses, the
charge cycle terminates and the CHRG pin assumes a
high impedance state, if it has not already done so. While
charging in constant-current mode, if the charge current
is decreased by thermal regulation or in order to maintain
the programmed input current limit, the charge time is
automatically increased. In other words, the charge time is
extended inversely proportional to the actual charge current
delivered to the battery. For Li-Ion and similar batteries that
require accurate fi nal fl oat potential, the internal bandgap
reference, voltage amplifi er and the resistor divider provide
regulation with ±0.8% accuracy.
Trickle Charge and Defective Battery Detection
At the beginning of a charge cycle, if the battery voltage
is below 2.9V, the charger goes into trickle charge reduc-
ing the charge current to 10% of the full-scale current.
If the low battery voltage persists for one quarter of the
programmed total charge time, the battery is assumed
to be defective, the charge cycle is terminated and the
CHRG pin output assumes a high impedance state. If
for any reason the battery voltage rises above ~2.9V the
charge cycle will be restarted. To restart the charge cycle
(i.e., when the dead battery is replaced with a discharged
battery), simply remove the input voltage and reapply it
or cycle the TIMER pin to 0V.
Programming Charge Current
The formula for the battery charge current is:
I
CHG
=I
PROG
• 50,000 =
LTC4090/LTC4090-5
PROG
. When the battery approaches the
R
V
PROG
PROG
• 50,000
15
4090fc