LTC4065 LINER [Linear Technology], LTC4065 Datasheet - Page 11

• Manufacturer Part Number: LTC4065
• Description: High Efficiency Battery Charger/USB Power Manager
• Manufacturer: LINER [Linear Technology]

operaTion
from V
the ideal diodes even when the battery charger is enabled.
The current at CLPROG is a precise fraction of the V
current. When a programming resistor and an averaging
capacitor are connected from CLPROG to GND, the voltage
on CLPROG represents the average input current of the
switching regulator. As the input current approaches the
programmed limit, CLPROG reaches 1.188V and power
delivered by the switching regulator is held constant.
Several ratios of current are available which can be set
to correspond to USB low and high power modes with a
single programming resistor.
The input current limit is programmed by various com-
binations of the D0, D1 and D2 pins as shown in Table 1.
The switching input regulator can also be deactivated
(USB Suspend).
The average input current will be limited by the CLPROG
programming resistor according to the following expres-
sion:
where I
V
R
h
the sample current delivered to CLPROG. Refer to the
Electrical Characteristics table for values of h
V
the USB specification for the average input current of 1x
or 5x mode will not be violated, provided that R
2.94k or greater.
Table 1 shows the available settings for the D0, D1 and
D2 pins.
Notice that when D0 is high and D1 is low, the switching
regulator is set to a higher current limit for increased
charging and power availability at V
will typically be used when there is line power available
from a wall adapter.
While not in current limit, the switching regulator’s
Bat-Track feature will set V
CLPROG
CLPROG
CLPROG
CLPROG
I
VBUS
BUS
BUSQ
is the ratio of the measured current at V
and I
= I
is the CLPROG servo voltage in current limit,
is the value of the programming resistor and
, load current will be drawn from the battery via
BUSQ
is the quiescent current of the LTC4088,
BUSQ
+
. Given worst-case circuit tolerances,
R
V
CLPROG
CLPROG
OUT
• h
(
to approximately 300mV
CLPROG
OUT
+ 1
. These modes
)
CLPROG
CLPROG
BUS
BUS
to
is
,
Table 1. Controlled Input Current Limit
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 fixed 3.6V as shown in Figure 2. This 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
range between the no-load voltage and slightly below the
battery voltage, indicated by the shaded region of Figure 2.
If there is no battery present when this happens, V
collapse to ground.
The voltage regulation loop compensation is controlled by
the capacitance on V
required for loop stability. Additional capacitance beyond
this value will improve transient response.
D0
0
0
0
0
1
1
1
1
4.5
4.2
3.9
3.6
3.3
3.0
2.7
2.4
D1
2.4
0
0
1
1
0
0
1
1
2.7
NO LOAD
Figure 2. V
OUT
D2
0
1
0
1
0
1
0
1
3.0
. An MLCC capacitor of 10µF is
BAT (V)
3.3
CHARGER
OUT
STATUS
Off
Off
Off
Off
Off
On
On
On
3.6
vs BAT
300mV
3.9
LTC4088
4088 F02
2.5mA (Susp High)
500µA (Susp Low)
4.2
100mA (1x)
100mA (1x)
500mA (5x)
500mA (5x)
BUS
I
1A (10x)
1A (10x)
BUS(LIM)
, V
OUT
11
OUT
may
4088fb
OUT
will