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参数资料
| 型号： | MAX1909ETI |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 电源管理 |
| 英文描述： | Multichemistry Battery Charger with Automatic System Power Selector |
| 中文描述： | 2-CHANNEL POWER SUPPLY SUPPORT CKT, QCC28 |
| 封装： | 5 X 5 MM, 0.80 MM HEIGHT, MO-220-WHHD-1, TQFN-28 |
| 文件页数： | 18/29页 |
| 文件大小： | 551K |
| 代理商： | MAX1909ETI |
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M
Multichemistry Battery Charger with Automatic
System Power Selector
18
______________________________________________________________________________________
A third method for inhibiting charging is to force ICTL
below 0.8V (typ). Approximately 3mA of supply current
is drawn from the AC adapter and 3μA is drawn from
the battery when the MAX1909 is in this state.
AC Adapter Detection and
Power-Source Selection
The MAX1909 includes a hysteretic comparator that
detects the presence of an AC power adapter and
automatically delivers power to the system load from
the appropriate available power source. When the
adapter is present, the open-drain ACOK output
becomes a high impedance. The switch threshold at
ACIN is 2.048V. Use a resistive voltage-divider from the
adapter
’
s output to the ACIN pin to set the appropriate
detection threshold. When charging, the battery is iso-
lated from the system load with the P-channel PDL
switch, which is biased off. When the adapter is absent,
the drives to the switches change state in a fast break-
before-make sequence. PDL begins to turn on 7.5μs
after PDS begins to turn off.
The threshold for selecting between the PDL and PDS
switches is set based on the voltage difference
between the DCIN and the BATT pins. If this voltage
difference drops below 100mV, the PDS is switched off
and PDL is switched on. Under these conditions, the
MAX1909 is completely powered down. The PDL switch
is kept on with a 100k
pulldown resistor when the
charger is powered down through ICTL,
PKPRES
, or
the AC adapter is removed.
The drivers for PDL and PDS are fully integrated. The
positive bias inputs for the drivers connect to the SRC
pin and the negative bias inputs connect to a negative
regulator referenced to SRC. With this arrangement, the
drivers can swing from SRC to approximately 10V
below SRC.
Conditioning Mode
The MAX1909 can be programmed to perform a condi-
tioning cycle to calibrate the battery
’
s fuel gauge. This
cycle consists of isolating the battery from the charger
and discharging it through the system load. When the
battery reaches 100% depth of discharge, it is then
recharged. Driving the MODE pin low places the
MAX1909 in conditioning mode, which stops the charg-
er from switching, turns the PDS switch off, and turns
the PDL switch on.
To utilize the conditioning mode function, the configura-
tion of the PDS switch must be changed to two source-
connected FETs to prevent the AC adapter from sup-
plying current to the system through the MOSFET
’
s
body diode. See Figure 2. The SRC pin must be con-
nected to the common source node of the back-to-back
FETs to properly drive the MOSFETs.
It is essential to alert the user that the system
is performing a conditioning cycle. If the user termi-
nates the cycle prematurely, the battery can be dis-
charged even though the system was running off AC
adapter for a substantial period of time. If the AC
adapter is in fact removed during conditioning, the
MAX1909 keeps the PDL switch on and the charger
remains off as it would in normal operation.
If the battery is removed during conditioning mode, the
PKPRES
control overrides conditioning mode. When
MODE is grounded and
PKPRES
goes high, the PDS
switch starts turning on within 7.5μs and the system is
powered from the AC adapter.
DC-to-DC Converter
The MAX1909 employs a buck regulator with a PMOS
high-side switch and a low-side NMOS synchronous
rectifier. The MAX1909 features a pseudo-fixed-fre-
quency, cycle-by-cycle current-mode control scheme.
The off-time is dependent upon V
DCIN
, V
BATT
, and a
time constant, with a minimum t
OFF
of 300ns. The
MAX1909 can also operate in discontinuous conduction
for improved light-load efficiency. The operation of the
DC-to-DC controller is determined by the following four
comparators as shown in Figure 4:
CCMP:
Compares the control point (lowest voltage
clamp (LVC)) against the charge current (CSI). The
high-side MOSFET on-time is terminated if the CCMP
output is high.
IMIN:
Compares the control point (LVC) against
0.15V (typ). If IMIN output is low, then a new cycle
cannot begin. This comparator determines whether
the regulator operates in discontinuous mode.
IMAX:
Compares the charge current (CSI) to the
internally fixed cycle-by-cycle current limit. The
current-sense voltage limit is 97mV. With RS2 =
0.015
,this corresponds to 6A. The high-side
MOSFET on-time is terminated if the IMAX output is
high and a new cycle cannot begin until IMAX goes
low. IMAX protects against sudden overcurrent
faults.
ZCMP:
Compares the charge current (CSI) to 333mA
(RS2 = 0.015
). The current-sense voltage threshold
is 5mV. If ZCMP output is high, then both MOSFETs
are turned off. The ZCMP comparator terminates the
switch on-time in discontinuous mode.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1909ETI+ | 功能描述:电池管理 Multichemistry Battery Chargers 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 |
| MAX1909ETI+T | 功能描述:电池管理 Multichemistry Battery Chargers 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 |
| MAX1909ETI-T | 功能描述:电池管理 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 |
| MAX1909EVKIT | 功能描述:电池管理 Evaluation Kit for the MAX1909 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 |
| MAX190ACNG | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
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