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参数资料
| 型号： | MAX1925 |
| 厂商： | Maxim Integrated Products, Inc. |
| 元件分类： | 数字信号处理 |
| 英文描述： | Fixed-Point Digital Signal Processor 548-FCBGA |
| 中文描述： | 开关模式单节Li+电池充电器 |
| 文件页数： | 13/16页 |
| 文件大小： | 443K |
| 代理商： | MAX1925 |
ing when the battery voltage drops, the MAX1925/MAX1926
ensure that the cell does not remain partially charged after
use when charger power is available.
Charging also restarts if input power is cycled or if the
charger is restarted by the EN or THRM input. If a new
battery is inserted, the charger must be restarted. If the
THRM functionality is used, the charger is automatically
restarted upon battery insertion. When THRM is not
used, toggle EN or connect THRM through a resistor to
be grounded with a battery-door latch switch.
Applications Information
Timer Capacitor and Fault Modes
The on-chip timer checks charge progress and issues
an alarm signal through a blinking
CHG
output when one
of the safety timers times out (see Table 1). All timers are
set by one external capacitor at CT. A 100nF value sets
the full-charge timer (t
FULLCHG
) to 3 hours, the
t
PREQUAL1
timer to (t
FULLCHG
)/1088 (10s), and the
t
PREQUAL2
timer at (t
FULLCHG
)/17 (10.67 minutes).
If the charger enters full-charge state (after the charging
current has fallen below C/8) before the full-charge timer
expires, no fault occurs, but if the timer expires before full
charge is reached, a fault is indicated (see Table 1).
A fault is also indicated if the battery voltage exceeds
4.35V. When the cell voltage exceeds 4.35V a fault alarm
is set, the
CHG
output blinks, and the PFET turns off.
To restart the charger after a fault occurs, the fault state
must be cleared by toggling EN, or by cycling input power
at IN (see Figure 1). Temperature faults do not need to be
cleared by EN. The MAX1925/MAX1926 resume charging
after the temperature returns to within the set window.
Inductor Selection
Because the MAX1925/MAX1926 is hysteretic, the con-
stant-current mode switching frequency is a function of
the inductance, sense resistance, and current-sense
hysteresis (30mV, from the
Electrical Characteristics
).
To minimize charge-current error:
where
I
CHG
is the acceptable charge-current error
and should usually be less than 1/4th the full charge
current. t
IDelay
is the current-sense comparator delay
(300ns typical). Calculate L for V
IN
= V
IN,MAX
, V
BATT
=
V
BATT,MIN
, with positive
I
CHG
and V
IN
= V
IN,MIN
,
V
BATT
= V
BATT,MAX
, with negative
I
CHG
. Use the larg-
er calculated value for L.
The resulting switching frequency in CCM is:
I
L
t
V
V
IN
BATT
Choose an inductor with an RMS and saturation current
rating according to the following equation:
+
(
where V
IPK
is the peak current-sense threshold (158mV typ).
Output Capacitor Selection
The ESR of the output capacitor influences the switch-
ing frequency of the charger during voltage regulation
I
V
R
V
V
L
SAT RMS
/
IPK
SET
IN
BATT IDelay
>
f
t
I
L
t
V
V
V
Switch
HYST
IDelay BATT
IDelay
HYST
IDelay
IN
BATT
BATT
>
× +
+ ×
2
+
× +
×
1
(
)
L
V
V
×
t
I
IN
BATT
Delay
CHG
>
×
2
(
)
×
2
M
Switch-Mode 1-Cell Li+ Chargers
______________________________________________________________________________________________________
13
PART
V
IN
ACON
CHARGING
CHG
LED
V
IN
> V
ACON
threshold (4.5V nom) and < 6.1V, and
V
IN
> V
BATT
LOW
YES
ON
(until charge complete)
V
IN
> V
ACON
threshold and
V
IN
< V
BATT
(Note: This state should never occur)
High Z
NO
OFF
MAX1925
V
IN
< V
ACON
threshold
High Z
NO
OFF
V
IN
> V
ACON
threshold (4.25V nom) and V
IN
> V
BATT
LOW
YES
ON
(until charge complete)
V
IN
> V
ACON
threshold and V
IN
< V
BATT
(Note: This state should never occur)
High Z
NO
OFF
MAX1926
V
IN
< V
ACON
Threshold
High Z
NO
OFF
Table 2.
ACON
Behavior vs. V
IN
相关PDF资料 |
PDF描述 |
|---|---|
| MAX1926 | Switch-Mode 1-Cell Li+ Chargers |
| MAX1926ETC | Switch-Mode 1-Cell Li+ Chargers |
| MAX1925ETC | Switch-Mode 1-Cell Li+ Chargers |
| MAX192AMJP | Low-Power, 8-Channel, Serial 10-Bit ADC |
| MAX192AEAP | Low-Power, 8-Channel, Serial 10-Bit ADC |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1925ETC | 功能描述:电池管理 Switch-Mode 1-Cell Li+ Charger 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 |
| MAX1925ETC+ | 功能描述:电池管理 Switch-Mode 1-Cell Li+ Charger 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 |
| MAX1925ETC+T | 功能描述:电池管理 Switch-Mode 1-Cell Li+ Charger 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 |
| MAX1925ETC-T | 功能描述:电池管理 Switch-Mode 1-Cell Li+ Charger 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 |
| MAX1926ETC | 功能描述:电池管理 Switch-Mode 1-Cell Li+ Charger 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 |
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