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参数资料
| 型号： | KIT34674EPEVBE |
| 厂商： | Freescale Semiconductor |
| 文件页数： | 15/26页 |
| 文件大小： | 0K |
| 描述： | KIT EVAL BOARD 10CH LED BACKLGHT |
| 标准包装： | 1 |
| 系列： | * |
FUNCTIONAL DESCRIPTION
FUNCTIONAL DEVICE OPERATION
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
The MC34674 moves through various charge states after
being powered, as shown in Figure 23 . The following
describes each state in detail.
POWER-ON RESET (POR)
When the input voltage rises above the rising power-on-
reset (POR) threshold, the charger resets the internal timer,
preparing for the start of a charging cycle. The falling edge of
the POR threshold is less than 2.6 V, making the MC34674
ideal for working with a current-limited AC/DC converter.
POWER-PRESENCE VERIFICATION
After the POR, the MC34674 indicates the power
presence to the users via a dual-color LED driven by the GRN
and RED pins. The indication is a sequence of four colors
using the dual-color LED in the sequence of red, green,
yellow (by turning on both colors) and OFF (by turning off
both colors). Each color is on for 0.5 seconds.
ENABLE/DISABLE VERIFICATION
The charger then tries to validate the logic level of the EN
input. The EN input is an active-low input with a weak internal
pull-down circuit. Leaving the EN pin floating is equivalent to
mode, an internal timer is reset to start counting the total
trickle-charge time. In the meantime, the charger begins to
measure the battery voltage. If the battery voltage rises
above the trickle-charge threshold before the timer finishes,
the charge cycle will enter the fast-charge mode that is
described next. If the timer expires before the voltage
reaching the trickle-charge threshold, the battery is
determined to be a faulty battery and a TIMEOUT fault
indication is issued. Then the charger turns off and the LED
indicates a yellow color.
FAST CHARGE MODE
The fast charge contains two modes, the constant-current
(CC)-mode and the constant-voltage (CV)-mode. As shown
in Figure 17 , the charge current is regulated at a constant
value in the CC-mode and the charger output voltage is
regulated at a constant 4.2 V in the CV-mode. The charge
current can be reduced by the die temperature regulation
loop when the die temperature reached 110°C. The CC-
mode current is set internally by Freescale. Available values
are given in Table 6 . Consult Freescale for values that are not
Table 6. Customer Selectable CC-Mode Current Values.
a low input. If the EN stays at the low state for more than
100ms, the charger is enabled. This 100ms filter applies to
both the rising and the falling edges of the EN input to prevent
mis-triggering of the EN signal by any transient event such as
an ESD event. The EN input has to stay in a new state
continuously for more than 100ms for the new state to be
recognized.
The VIN-BAT comparator output is also a condition for
enabling the charger. When the input voltage V IN is lower
than the BAT pin voltage V BAT by the V OS , the charger is
disabled and stays in the Enable Verification state.
BATTERY CONNECTION VERIFICATION
No.
1
2
3
4
5
6
7
8
I CHG (mA)
50
100
150
200
250
300
350
400
No.
9
10
11
12
13
14
15
16
I CHG (mA)
450
500
550
650
750
850
950
1050
Once enabled, the charger starts to verify if a battery is
connected. The battery connection verification takes 0.5
seconds, during which the dual-color LED and the charger
are off. If a battery is found, the charger starts to enter the
trickle-charge mode; otherwise, it turns on the yellow color
LED for 1 second, then turns off the LED for 0.5 seconds, and
then tries to verify the connection again. The verification flow
creates an equivalent 0.5 Hz yellow blinking LED indication if
there is no battery connected. Once a battery is inserted, the
charger will detect it and enter the trickle-charge mode.
TRICKLE-CHARGE MODE
The charger always starts charging with the trickle-charge
mode. The trickle-charge mode current is set to 10% of the
constant-current (CC) charge mode current that is described
next. In trickle-charge mode the charger is on and the LED
When entering the fast charge mode, the internal timer is
reset again to limit the total fast charge time. The time limit for
the fast charge mode is 8 times of that of the trickle-charge
mode. When the charge completion conditions are detected
or when the total charge time limit is reached, the charger
enters the charge completion state.
The LED indicates the red color in the fast charge mode.
CHARGE COMPLETION
The criterion for the charge completion is for the charge
current to drop below the end-of-charge (EOC) threshold in
the CV-mode. The EOC threshold is set to 10% of the CC-
mode current. To ensure that no transient current will mis-
trigger the EOC indication, two additional criteria are required
to be met. The first one is, the battery voltage needs to be
above the recharge threshold. The second is, the charge
indicates the red color. When entering the trickle-charge
34674
Analog Integrated Circuit Device Data
Freescale Semiconductor
15
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| KIT34675EPEVBE | 功能描述:电源管理IC开发工具 28V-INPUT-VOLT SNGL RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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