LTC3576EUFE#PBF Linear Technology, LTC3576EUFE#PBF Datasheet - Page 20

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

Specifications of LTC3576EUFE#PBF

• 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: -

LTC3576/LTC3576-1
The input current limit is programmed by the I
I
has fi ve possible settings ranging from the USB suspend
limit of 500μA up to 1A for wall adapter applications. Two
of these settings are specifi cally intended for use in the
100mA and 500mA USB applications. Refer to Table 1 for
current limit settings using the I
Table 6 for current limit settings using the I
Table 1. USB Current Limit Settings Using I
When the switching regulator is activated, the average
input current will be limited by the CLPROG programming
resistor according to the following expression:
where I
LTC3576-1, V
current limit, R
resistor and h
rent at V
Refer to the Electrical Characteristics table for values of
h
tolerances, the USB specifi cation for the average input
current in 100mA or 500mA mode will not be violated,
provided that R
While not in current limit, the switching regulator’s
Bat-Track feature will set V
above the voltage at BAT. However, if the voltage at BAT
is below 3.3V, and the load requirement does not cause
the switching regulator to exceed its current limit, V
will regulate at a fi xed 3.6V as shown in Figure 2. This
instant-on operation will allow a portable product to run
immediately when power is applied without waiting for the
battery to charge. If the load does exceed the current limit
at V
slightly below the battery voltage, indicated by the shaded
region of Figure 2.
OPERATION
20
LIM1
CLPROG
I
I
LIM1
VBUS
BUS
0
0
1
1
pins or by the I
, V
VBUSQ
BUS
, V
=I
OUT
VBUSQ
CLPROG
to the sample current delivered to CLPROG.
I
LIM0
CLPROG
0
1
0
1
will range between the no-load voltage and
CLPROG
is the quiescent current of the LTC3576/
CLPROG
CLPROG
+
and I
2
R
USB SETTING
1× Mode (USB 100mA Limit)
10× Mode (Wall 1A Limit)
Low Power Suspend (USB 500μA Limit)
5× Mode (USB 500mA Limit)
V
C serial port. The input current limit
CLPROG
CLPROG
is the CLPROG servo voltage in
is the ratio of the measured cur-
is 3.01k or greater.
is the value of the programming
VBUSQ
OUT
• h
. Given worst-case circuit
(
to approximately 300mV
LIM0
CLPROG
LIM0
and I
+ 1
and I
LIM1
2
)
C port.
LIM1
LIM0
pins and
and
OUT
For very low-battery voltages, the battery charger acts like
a load and, due to limited input power, its current will tend
to pull V
V
automatically detects that V
battery charge current as needed. This reduction ensures
that load current and voltage are always prioritized while
allowing as much battery charge current as possible. See
Battery Charger Over Programming in the Applications
Information section.
The voltage regulation loop is compensated by the ca-
pacitance on V
for loop stability. Additional capacitance beyond this value
will improve transient response.
An internal undervoltage lockout circuit monitors V
keeps the switching regulator off until V
4.30V and is about 200mV above the battery voltage.
Hysteresis on the UVLO turns off the regulator if V
falls below 4V or to within 50mV of the battery voltage.
When this happens, system power at V
from the battery via the ideal diode(s).
Bidirectional PowerPath Switching Regulator—
Step-Up Mode
For USB on-the-go applications, the bidirectional
PowerPath switching regulator acts as a step-up converter
to deliver power from V
can come from the battery or the output of the external
OUT
from falling below this level, an undervoltage circuit
OUT
4.5
4.2
3.9
3.6
3.3
3.0
2.7
2.4
below the 3.6V instant-on voltage. To prevent
2.4
OUT
2.7
NO LOAD
. A 10μF MLCC capacitor is required
Figure 2. V
3.0
OUT
BAT (V)
to V
3.3
OUT
OUT
BUS
is falling and reduces the
3.6
vs BAT
300mV
. The power from V
3.9
OUT
3576 F02
BUS
4.2
will be drawn
rises above
BUS
3576fb
and
OUT
BUS