TCA6507_10 Datasheet, PDF (13/32 Pages) Texas Instruments – LOW-VOLTAGE 7-BIT I2C AND SMBus LED DRIVER WITH INTENSITY CONTROL AND SHUTDOWN

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TCA6507
LOW-VOLTAGE 7-BIT I²C AND SMBus LED DRIVER
WITH INTENSITY CONTROL AND SHUTDOWN
SCPS164B – MAY 2007 – REVISED NOVEMBER 2007
Table 19. BANK0
C2
C1
0
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
C0
STARTING POINT OF INTENSITY CYCLE
0
Beginning at region A1 in Table 15 and Figure 6
1
Beginning at region B1 in Table 15 and Figure 6
0
Beginning at region C1 in Table 15 and Figure 6
1
Beginning at region D in Table 15 and Figure 6
0
Beginning at region A2 in Table 15 and Figure 6
1
Beginning at region B2 in Table 15 and Figure 6
0
Beginning at region C2 in Table 15 and Figure 6
1
Beginning at region E in Table 15 and Figure 6
Power-On Reset
When power (from 0 V) is applied to V_CC, an internal power-on reset holds the TCA6507 in a reset condition until
V_CC has reached V_POR. At that point, the reset condition is released, and the TCA6507 registers and I²C/SMBus
state machine initialize to their default states.
After the initial power-up phase, V_CCI must be lowered to below 0.2 V and then back up to the operating voltage
(V_CCI) for a power-reset cycle.
Enable and Reset
If the enable (EN) input is set to low, the TCA6507 is put in the standby or shutdown mode. In this mode, the
oscillator is turned off, the registers are returned to their default state, and the the I²C/SMBus state machine is
initialized. This mode is useful for low power consumption. An internal filtering circuit prevents negative glitches
from accidentally shutting down the device. EN must be low for a minimum of approximately 60 µs to ensure a
shutdown state.
The system master can reset the TCA6507 in the event of a timeout or other improper operation by setting EN
low for a minimum of approximately 60 µs. This has the same effect as a power-on reset without depowering the
TCA6507.
The oscillator start up time (t_OSC) is measured from the point when EN is set high.
Bus Transactions
Data is exchanged between the master and TCA6507 through read and write commands.
Reads
The bus master first must send the TCA6507 address with the LSB set to a logic 0 (see Figure 5 for device
address). The command byte is sent after the address and determines which register is accessed. After a restart,
the device address is sent again but, this time, the LSB is set to a logic 1. Data from the register defined by the
command byte then is sent by the TCA6507 (see Figure 10). Data is clocked into the register on the rising edge
of the ACK clock pulse.
Copyright © 2007, Texas Instruments Incorporated
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