MAX8834Z データシートの表示（PDF） - Maxim Integrated
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MAX8834Z Datasheet PDF : 44 Pages
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MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
IINDLED = FULL SCALE
IINDLED = 1/2 SCALE
0mA
Figure 5. Ramp-Up Behavior
128ms
256ms
IINDLED = FULL SCALE
IINDLED = 1/2 SCALE
0mA
Figure 6. Ramp-Down Behavior
128ms
256ms
tIND_OFF
tIND_ON
512ms
512ms
tIND_OFF
1024ms
1024ms
tIND_ON
tIND_OFF
IIND_LED = IND_LED[4:0]
IIND_LED = CODE 0111
IIND_LED = CODE 0011
IIND_LED = OFF
t = tIND_RU
32
t = tIND_RD
32
Figure 7. Combining RAMP Function and Blink Timer
programmed current not being reached during the ON
time, or the INDLED current not returning to 0mA during
the OFF time. See Figure 7.
tIND _ ON
≥
tIND _RU
32
(IND _ LED + 1)
tIND _ OFF
≥
tIND _RD
32
(IND _ LED + 1)
where IND_LED is the code from 0 to 31 specified in
the IND_LED[4:0].
LED Enable Input (LED_EN)
The LED_EN logic input can enable/disable the FLED1,
FLED2, and INDLED current regulators. It can be
programmed to control movie mode, flash mode, and
indicator mode by using the IND_EN, MOVIE_EN,
and FLASH_EN bits, respectively. See Table 8 for
more information.
If FLED1/FLED2 is enabled for both movie and flash
modes at the same time, flash mode has priority. Once
the safety timer expires, the current regulator then
returns to the movie mode.
Watchdog Timer
The MAX8834Y/MAX8834Z include a watchdog timer
function that can be programmed using the I2C inter-
face from 4 seconds to 16 seconds with a 4-second
step. If the watchdog timer expires, the MAX8834Y/
MAX8834Z interpret it as an indication that the system
is no longer responding and enters safe mode. In safe
mode, the MAX8834Y/MAX8834Z disable all current
regulators and the step-up DC-DC converter to prevent
potential damage to the system. The I2C setting for the
respective registers does not change, therefore, reset-
ting the watchdog timer reverts the MAX8834Y/
MAX8834Z back to the state present before entering
safe mode.
14
Maxim Integrated
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