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| 型号： | MAX8568AETE+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 13/17页 |
| 文件大小： | 0K |
| 描述： | IC BATT MANAGE LITH 16-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 功能： | 备份管理 |
| 电池化学： | 锂离子（Li-Ion）；镍金属氢化物（NiMH） |
| 电源电压： | 2.8 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-WFQFN 裸露焊盘 |
| 供应商设备封装： | 16-TQFN-EP（3x3） |
| 包装： | 带卷 (TR) |
Complete Backup-Management ICs
for Lithium and NiMH Batteries
Inductor Selection
The control scheme of the MAX8568 permits flexibility in
choosing an inductor. A 10μH inductor performs well in
most applications. Smaller inductance values typically
offer smaller physical size for a given series resistance,
allowing the smallest overall circuit dimensions. Circuits
using larger inductance may provide higher efficiency
and exhibit less ripple, but also may reduce the maxi-
mum output current. This occurs when the inductance is
sufficiently large to prevent the LX current limit (I LIM )
from being reached before the maximum on-time
(t ON(MAX) ) expires.
For maximum output current, choose the inductor value
so that the controller reaches the current limit before
the maximum on-time is reached:
V BK × t ON(MAX )
L <
I LIM
where t ON(MAX) is typically 5μs, and the current limit (I LIM )
is typically 500mA (see the Electrical Characteristics
table).
For larger inductor values, determine the peak inductor
current (I PEAK ) by:
LDO Capacitor Selection
Capacitors are required at the LDO output of the
MAX8568 for stable operation over the full load and tem-
perature range. A 4.7μF or greater X5R or X7R ceramic
capacitor is recommended. To reduce noise and
improve load-transient response, larger output capaci-
tors up to 10μF can be used. Surface-mount ceramic
capacitors have very low ESR and are commonly avail-
able in values up to 10μF. Note that some ceramic
dielectrics, such as Z5U and Y5V, exhibit large capaci-
tance and ESR variation with temperature and require
larger than the recommended values to maintain stability
and good load-transient response over temperature.
External MOSFET Drivers—OD1, OD2
OD1 and OD2 are open-drain outputs and are
designed to be connected to the gates of external p-
channel MOSFETs (see Figure 7). These MOSFETs
connect the main system power supplies (I/O IN and
MEM IN) to the system loads (I/O OUT and MEM OUT)
during normal operation. During backup, they discon-
nect the power supplies from the system loads to pre-
vent the power supplies from drawing backup current
away from the system. For this reason, the MOSFETs
are connected “backwards ” from what might be
expected. The source of the MOSFETs are connected
I PEAK =
V BK × t ON(MAX )
L
to the system load side (I/O OUT and MEM OUT). The
MOSFETs’ purpose is to block current flow from the
backup supply (BKSU) to the main supplies (I/O IN and
Setting the Output Voltage
The output voltage is set to 2.5V or 3.3V, or is
adjustable. Connect BKV to GND for 3.3V, and BKV to
BKSU for 2.5V. The adjustable output voltage is set
from 2.5V to 5V using external resistors R1 and R2
(Figure 7). Since FB leakage is 50nA (max), select
feedback resistor R2 in the 100k ? to 1M ? range.
Calculate R1 as follows:
MEM IN). They do not block current flow from I/O IN to
I/O OUT and from MEM IN to MEM OUT. Even when off,
the MOSFET body diodes allow current to pass in that
direction.
OD1 is intended to drive the MOSFET switch for I/O IN
and I/O OUT, while OD2 is intended to drive the MOSFET
switch for MEM IN and MEM OUT. See the T ypical
Operating Characteristics and Figure 1 for typical opera-
R 1 = R 2 ? BKSU
1 ?
? V
? V BKV
?
?
?
tion of OD1 and OD2.
External MOSFET Selection
The external MOSFET should be chosen based upon
where V BKV = 1.21V.
LDO
The LDO output voltage is preset to 2.5V for the
MAX8568A and 1.8V for the MAX8568B. The LDO can
supply up to 10mA. The LDO output voltage is not
adjustable.
R DS(ON) and gate capacitance. When V INOK > 2.43V
(main battery > 2.8V), the current required for normal
operation of I/O and MEM goes through these external
MOSFETs. Choose an R DS(ON) that minimizes the
MOSFET voltage drop. When V INOK < 2.43V, the
MOSFET turns off, and MEM and I/O are powered by
the MAX8568. The gate capacitance of the external
MOSFET must discharge through the external gate-to-
source resistor. This discharge time determines how
quickly the main supply is disconnected and isolated.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8568BETE | 功能描述:电池管理 Backup-Mgt IC for Li & NiMH Bat RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX8568BETE-T | 功能描述:电池管理 Backup-Mgt IC for Li & NiMH Bat RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX8569AETT+ | 制造商:Maxim Integrated Products 功能描述:CONV DC-DC SGL-OUT STEP UP 6TDFN EP - Rail/Tube |
| MAX8569AETT+T | 功能描述:直流/直流开关转换器 200mA Step-Up DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX8569AEUT | 制造商:Maxim Integrated Products 功能描述:200MA STEP-UP DC-DC CONVERTERS IN 6 - Rail/Tube |
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