LTC3576EUFE#TRPBF Linear Technology, LTC3576EUFE#TRPBF Datasheet - Page 23

• Manufacturer Part Number: LTC3576EUFE#TRPBF
• Description: IC POWER MANAGER W/USB OTG 38QFN
• Manufacturer: Linear Technology

Specifications of LTC3576EUFE#TRPBF

• Applications: Handheld/Mobile Devices
• Voltage - Supply: 4.35 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 38-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -

then all of the application power will be provided by the
battery via the ideal diodes. The ideal diode(s) will be fast
enough to keep V
age capacitance required for the switching regulator. The
internal ideal diode consists of a precision amplifi er that
activates a large on-chip P-channel MOSFET whenever
the voltage at V
the voltage at BAT. Within the amplifi er’s linear range, the
small-signal resistance of the ideal diode will be quite low,
keeping the forward drop near 15mV. At higher current
levels, the MOSFET will be in full conduction.
To supplement the internal ideal diode, an external
P-channel MOSFET may be added from BAT to V
IDGATE pin of the LTC3576/LTC3576-1 drives the gate of
the external P-channel MOSFET for automatic ideal diode
control. The source of the external P-channel MOSFET
should be connected to V
nected to BAT. Capable of driving a 1nF load, the IDGATE
pin can control an external P-channel MOSFET transistor
having an on-resistance of 30mΩ or lower.
Suspend LDO
If the LTC3576/LTC3576-1 are confi gured for USB suspend
mode, the bidirectional switching regulator is disabled and
the suspend LDO provides power to the V
ing there is power available to V
the battery from running down when the portable product
has access to a suspended USB port. Regulating at 4.6V,
this LDO only becomes active when the switching converter
is disabled (suspended). The suspend LDO sends a scaled
OPERATION
1000
2200
2000
1800
1600
1400
1200
800
600
400
200
Figure 4. Ideal Diode V-I Characteristics
0
0
OUT
FORWARD VOLTAGE (mV) (BAT – V
60
OUT
IDEAL DIODE
is approximately 15mV (V
120
VISHAY Si2333
OPTIONAL EXTERNAL
IDEAL DIODE
LTC3576-1
SEMICONDUCTOR
LTC3576/
from drooping with only the stor-
180
MBRM120LT3
OUT
240 300
and the drain should be con-
ON
BUS
). This LDO will prevent
360
OUT
420
3576 F04
OUT
)
480
pin (presum-
FWD
OUT
) below
. The
copy of the V
servo to approximately 100mV in this mode. To remain
compliant with the USB specifi cation, the input to the LDO
is current limited so that it will not exceed the low power
or high power suspend specifi cation. If the load on V
exceeds the suspend current limit, the additional current
will come from the battery via the ideal diode(s).
3.3V Always-On LDO Supply
The LTC3576/LTC3576-1 include a low quiescent current
low dropout regulator that is always powered. This LDO
can be used to provide power to a system pushbutton
controller, standby microcontroller or real time clock. De-
signed to deliver up to 20mA, the always-on LDO requires
at least a 1μF low impedance ceramic bypass capacitor
for compensation. The LDO is powered from V
therefore will enter dropout at loads less than 20mA as
V
should be disabled by connecting it to V
Battery Charger
The LTC3576/LTC3576-1 include a constant-current/con-
stant-voltage battery charger with automatic recharge,
automatic termination by safety timer, low voltage trickle
charging, bad cell detection and thermistor sensor input
for out-of-temperature charge pausing.
Battery Preconditioning
When a battery charge cycle begins, the battery charger
fi rst determines if the battery is deeply discharged. If the
battery voltage is below V
trickle charge feature sets the battery charge current to
10% of the programmed value. If the low voltage persists
for more than 1/2 hour, the battery charger automatically
terminates and indicates via the CHRG pin that the battery
was unresponsive.
Once the battery voltage is above 2.85V, the charger begins
charging in full power constant-current mode. The cur-
rent delivered to the battery will try to reach 1030/R
Depending on available input power and external load
conditions, the battery charger may or may not be able
to charge at the full programmed rate. The external load
will always be prioritized over the battery charge current.
OUT
falls near 3.3V. If the LDO3V3 output is not used, it
BUS
LTC3576/LTC3576-1
current to the CLPROG pin, which will
TRKL
, typically 2.85V, an automatic
OUT
.
OUT
23
PROG
, and
3576fb
OUT
.