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参数资料
| 型号： | MAX8819AETI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 20/29页 |
| 文件大小： | 0K |
| 描述： | IC PMIC W/INT CHARGER 28TQFN-EP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 手持/移动设备 |
| 电源电压： | 4.1 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（4x4） |
| 包装： | 带卷 (TR) |
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PMIC with Integrated Chargers and Smart
Power Selector in a 4mm x 4mm TQFN
Charge Current (CISET)
As shown in Table 2 and Figure 4, a resistor from CISET
to ground (R CISET ) sets the maximum fast-charge cur-
rent (I CHGMAX ), the charge current in prequalification
mode (I PREQUAL ), and the top-off threshold (I TOPOFF ).
The MAX8819_ supports values of I CHGMAX from 200mA
to 1000mA. Select the R CISET as follows:
The IC uses external resistor-dividers to set the step-
down output voltages between 1V and V SYS . Use at
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 FBL ). The recom-
mended value is 100k Ω . Next, calculate the value of the
resistor connected from FB_ to the output (R FBH ):
R FBH = R FBL × ? OUT ? 1 ?
R CISET = 2000 ×
1 . 5 V
I CHGMAX
? V ?
? 1 . 0 V ?
Determine I CHGMAX by considering the characteristics
I CHGMAX = 2000 x
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 CISET , calculate I CHGMAX ,
I PREQUAL , and I TOPOFF as follows:
1 . 5 V
R CISET
I PREQUAL = I TOPOFF = 10 % x I CHGMAX
Step-Down Converters
(REG1, REG2, REG3)
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 SYS from 2.6V to 5.5V. Undervoltage lockout ensures
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.
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.
Step-Down Control Scheme
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.
Step-Down Dropout and Minimum Duty Cycle
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 DO ) is calculated as follows:
V DO = I LOAD ( R P + R LSR )
where:
R P = p-channel power switch R DS(ON)
R LSR = external inductor ESR
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.
Step-Down Input Capacitor
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.
20
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相关代理商/技术参数 |
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| MAX8819AEVKIT+ | 功能描述:PMIC 解决方案 Evaluation Kit for the MAX8819A MAX8819B MAX8819C and MAX8819D RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8819BETI+ | 功能描述:PMIC 解决方案 PMIC w/Charger & Smart Power Selector RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8819BETI+T | 功能描述:PMIC 解决方案 PMIC w/Charger & Smart Power Selector RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8819CETI+ | 功能描述:PMIC 解决方案 PMIC w/Charger & Smart Power Selector RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8819CETI+T | 功能描述:PMIC 解决方案 PMIC w/Charger & Smart Power Selector RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
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