LTC4055EUF#TRPBF Linear Technology, LTC4055EUF#TRPBF Datasheet - Page 14

• Manufacturer Part Number: LTC4055EUF#TRPBF
• Description: IC USB PWR MNGR BATT CHRGR 16QFN
• Manufacturer: Linear Technology

Specifications of LTC4055EUF#TRPBF

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 4.35 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-WQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

USB CURRENT LIMIT AND CHARGE CURRENT
CONTROL
The current limit and charger control circuits of the
LTC4055/LTC4055-1 are designed to limit input current
as well as control battery charge current as a function of
I
The programmed battery charge current, I
Input current, I
current and the OUT pin output current.
The current limiting circuitry in the LTC4055/LTC4055-1
can and should be confi gured to limit current to 500mA
for USB applications (selectable using the HPWR pin and
programmed using the CLPROG pin).
When programmed for 500mA current limit and 500mA
or more of charging current, powered from IN1/IN2
and battery charging is active, control circuitry within
LTC4055/LTC4055-1
OPERATION
I
14
OUT
CHG
–100
I
I
600
500
400
200
100
300
CL
IN
. The programmed current limit, I
0
=
= I
0
(2a) High Power Mode/Full Charge
=
⎛
⎜ ⎜
⎝
⎛
⎜ ⎜
⎝
48 500
R
OUT
R
(R
PROG
100
49 000
,
CLPROG
PROG
+ I
,
IN
200
BAT
•
= R
, is equal to the sum of the BAT pin output
V
I
I
LOAD
IN
PROG
•
CLPROG
300
V
(mA)
CLPROG
⎞
⎟ ⎟ =
⎠
400
I
CHARGING
I
= 97.6k)
LOAD
BAT
48 500
R
⎞
⎟ ⎟ =
⎠
500
,
PROG
Figure 2. Input and Battery Currents as a Function of Load Current
(IDEAL DIODE)
4055 F02a
R
49 000
C
I
600
BAT
V
,
L L PROG
CL
CHG
V
is defi ned as:
120
100
–20
80
40
20
60
0
, is defi ned as:
0
(2b) Low Power Mode/Full Charge
(R
20
PROG
40
= R
I
I
IN
LOAD
CLPROG
60
I
CHARGING
(mA)
the LTC4055/LTC4055-1 reduces the battery charging
current such that the sum of the battery charge current
and the load current does not exceed 500mA (100mA
when HPWR is low, see Figure 2) The battery charging
current goes to zero when load current exceeds 500mA
(80mA when HPWR is low). If the load current is greater
than the current limit, the output voltage will drop to just
under the battery voltage where the ideal diode circuit will
take over and the excess load current will be drawn from
the battery (shaded region in Figure 2).
PROGRAMMING CURRENT LIMIT
The formula for programming current limit is:
where V
the total resistance from the CLPROG pin to ground.
For example, if typical 490mA current limit is required,
calculate:
In USB applications, the minimum value for R
be 105k. This will prevent the application current from
BAT
I
LOAD
I
R
80
CL
= 97.6k)
CLPROG
=
100
CLPROG
I
(IDEAL DIODE)
CLPROG
4055 F02b
I
=
120
BAT
490
is the CLPROG pin voltage and R
•
1
V
–100
49 000
mA
600
500
400
200
100
300
0
,
0
•
(R
I
49 000 100
CL
PROG
(2c) High Power Mode with
100
=
I
BAT
= 500mA and I
,
R
V
= I
= 196k, R
CLPROG
CLPROG
CHG
200
CHARGING
=
I
I
I
BAT
IN
LOAD
300
(mA)
CLPROG
•
k
CHG
49 000
400
I
BAT
I
LOAD
,
CLPROG
= 250mA
= I
= 97.6k)
CL
500
(IDEAL DIODE)
CLPROG
– I
4055 F02c
OUT
should
I
600
BAT
4055fb
is