MAX8819BETI+T Maxim Integrated Products, MAX8819BETI+T Datasheet - Page 20

• Manufacturer Part Number: MAX8819BETI+T
• Description: IC PMIC W/INT CHARGER 28-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8819BETI+T

• Applications: Handheld/Mobile Devices
• Voltage - Supply: 2.6 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PMIC with Integrated Chargers and Smart
Power Selector in a 4mm x 4mm TQFN
As shown in Table 2 and Figure 4, a resistor from CISET
to ground (R
rent (I
mode (I
The MAX8819_ supports values of I
to 1000mA. Select the R
Determine I
of the battery. It is not necessary to limit the charge cur-
rent based on the capabilities of the expected AC-to-
DC adapter or USB/DC input current limit, the system
load, or thermal limitations of the PCB. The IC automati-
cally lowers the charging current as necessary to
accommodate for these factors.
For the selected value of R
I
REG1, REG2, and REG3 are high-efficiency, 2MHz cur-
rent-mode step-down converters with adjustable outputs.
REG1 is designed to deliver 400mA for the MAX8819A/
MAX8819B and 550mA for the MAX8819C. REG2 and
REG3 are designed to deliver 300mA for the MAX8819A/
MAX8819B and 500mA for the MAX8819C.
The PV13 step-down regulator power input must be
connected to SYS. PV2 must also be connected to SYS
for normal operation of REG2, but REG2 can be dis-
abled by connecting PV2, FB2, and PG2 to GND. When
REG2 is disabled, LX2 can be unconencted or con-
nected to GND. The step-down regulators operate with
V
that the step-down regulators do not operate with SYS
below 2.55V (max).
See the Step-Down Converter Enable/Disable (EN123)
and Sequencing section for how to enable and disable
the step-down converters. When enabled, the
MAX8819_ gradually ramps each output up during a
2.6ms soft-start time. When enabled, the MAX8819C
sequentially ramps up each output. Soft-start eliminates
input current surges when regulators are enabled.
See the Step-Down Control Scheme section for informa-
tion about the step-down converters control scheme.
20
PREQUAL
SYS
______________________________________________________________________________________
from 2.6V to 5.5V. Undervoltage lockout ensures
CHGMAX
PREQUAL
I
PREQUAL
, and I
CHGMAX
CISET
R
I
), the charge current in prequalification
CISET
CHGMAX
TOPOFF
), and the top-off threshold (I
) sets the maximum fast-charge cur-
=
by considering the characteristics
=
I
TOPOFF
2000
CISET
as follows:
=
Step-Down Converters
2000
×
CISET
(REG1, REG2, REG3)
as follows:
I
CHGMAX
Charge Current (CISET)
=
1 5 .
10
x
, calculate I
CHGMAX
V
%
R
1 5
CISET
.
x I
V
CHGMAX
from 200mA
CHGMAX
TOPOFF
).
,
The IC uses external resistor-dividers to set the step-
down output voltages between 1V and V
least 10μA of bias current in these dividers to ensure no
change in the stability of the closed-loop system. To set
the output voltage, select a value for the resistor con-
nected between FB_ and GND (R
mended value is 100kΩ. Next, calculate the value of the
resistor connected from FB_ to the output (R
REG1, REG2, and REG3 are optimized for high, medi-
um, and low output voltages, respectively. The highest
overall efficiency occurs with V1 set to the highest out-
put voltage and V3 set to the lowest output voltage.
At light load, the step-down converter switches only as
needed to supply the load. This improves light-load effi-
ciency. At higher load currents (~80mA), the step-down
converter transitions to fixed 2MHz switching.
All of the step-down regulators are capable of operat-
ing in 100% duty-cycle dropout, however, REG1 has
been optimized for this mode of operation. During
100% duty-cycle operation, the high-side p-channel
MOSFET turns on constantly, connecting the input to
the output through the inductor. The dropout voltage
(V
where:
R
R
The minimum duty cycle for all step-down regulators is
12.5% (typ), allowing a regulation voltage as low as 1V
over the full SYS operating range. REG3 is optimized
for low duty-cycle operation.
The input capacitor in a step-down converter reduces
current peaks drawn from the power source and
reduces switching noise in the controller. The imped-
ance of the input capacitor at the switching frequency
must be less than that of the source impedance of the
supply so that high-frequency switching currents do not
pass through the input source.
P
LSR
DO
= p-channel power switch R
) is calculated as follows:
= external inductor ESR
Step-Down Dropout and Minimum Duty Cycle
R
V
FBH
DO
=
=
R
I
LOAD
FBL
Step-Down Control Scheme
Step-Down Input Capacitor
×
(
⎛
⎜
⎝
R
V
P
1 0
DS(ON)
OUT
.
+
V
R
LSR
−
FBL
1
⎞
⎟
⎠
)
). The recom-
SYS
FBH
. Use at
):