TCA9546A Datasheet, PDF (19/31 Pages) Texas Instruments – Low Voltage 4-Channel I2C and SMBus Switch with Reset Function

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TCA9546A
SCPS205A – APRIL 2014 – REVISED FEBRUARY 2015
11 Power Supply Recommendations
The operating power-supply voltage range of the TCA9546A is 1.65 V to 5.5 V applied at the VCC pin. When the
TCA9546A is powered on for the first time or anytime the device needs to be reset by cycling the power supply,
the power-on reset requirements must be followed to ensure the I²C bus logic is initialized properly.
11.1 Power-On Reset Requirements
In the event of a glitch or data corruption, TCA9546A can be reset to its default conditions by using the power-on
reset feature. Power-on reset requires that the device go through a power cycle to be completely reset. This
reset also happens when the device is powered on for the first time in an application.
A power-on reset is shown in Figure 19.
V_CC
Ramp-Down
Ramp-Up
V_CC drops below V_PORF – 50 mV
V_{CC_TRR}
V_{CC_FT}
Time to Re-Ramp
V_{CC_RT}
Time
Figure 19. V_CC is Lowered Below the POR Threshold, Then Ramped Back Up to V_CC
Table 2 specifies the performance of the power-on reset feature for TCA9546A for both types of power-on reset.
Table 2. Recommended Supply Sequencing And Ramp Rates⁽¹⁾
V_{CC_FT}
V_{CC_RT}
V_{CC_TRR}
V_{CC_GH}
V_{CC_GW}
V_PORF
V_PORR
PARAMETER
Fall time
Rise time
Time to re-ramp (when V_CC drops below V_PORF(min) – 50 mV or
when V_CC drops to GND)
Level that V_CC can glitch down to, but not cause a functional
disruption when V_{CC_GW} = 1 μs
Glitch width that will not cause a functional disruption when
V_{CC_GH} = 0.5 × V_CC
Voltage trip point of POR on falling V_CC
Voltage trip point of POR on rising V_CC
See Figure 19
See Figure 19
See Figure 19
See Figure 20
See Figure 20
See Figure 21
See Figure 21
MIN TYP
1
0.1
40
0.8
1.05
(1) All supply sequencing and ramp rate values are measured at T_A = 25°C
MAX
100
100
1.2
10
1.25
1.5
UNIT
ms
ms
μs
V
μs
V
V
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