Datasheet

TPS61160
TPS61161
www.ti.com SLVS791C –NOVEMBER 2007–REVISED APRIL 2012
All bits are transmitted MSB first and LSB last. Figure 16 shows the protocol without acknowledge request (Bit
RFA = 0), Figure 16 with acknowledge (Bit RFA = 1) request. Prior to both bytes, device address byte and data
byte, a start condition must be applied. For this, the CTRL pin must be pulled high for at least t
start
(2μs) before
the bit transmission starts with the falling edge. If the CTRL pin is already at high level, no start condition is
needed prior to the device address byte. The transmission of each byte is closed with an End of Stream
condition for at least t
EOS
(2μs).
The bit detection is based on a Logic Detection scheme, where the criterion is the relation between t
LOW
and
t
HIGH
. It can be simplified to:
High Bit: t
HIGH
> t
LOW
, but with t
HIGH
at least 2x t
LOW
, see Figure 16.
Low Bit: t
HIGH
< t
LOW
, but with t
LOW
at least 2x t
HIGH
, see Figure 16.
The bit detection starts with a falling edge on the CTRL pin and ends with the next falling edge. Depending on
the relation between t
HIGH
and t
LOW
, the logic 0 or 1 is detected.
The acknowledge condition is only applied if:
• Acknowledge is requested by a set RFA bit.
• The transmitted device address matches with the device address of the device.
• 16 bits is received correctly.
If the device turns on the internal ACKN-MOSFET and pulls the CTRL pin low for the time t
ACKN
, which is 512μs
maximum then the Acknowledge condition is valid after an internal delay time t
valACK
. This means that the internal
ACKN-MOSFET is turned on after t
valACK
, when the last falling edge of the protocol was detected. The master
controller keeps the line low in this period. The master device can detect the acknowledge condition with its input
by releasing the CTRL pin after t
valACK
and read back a logic 0. The CTRL pin can be used again after the
acknowledge condition ends.
Note that the acknowledge condition may only be requested in case the master device has an open drain output.
For a push-pull output stage, the use a series resistor in the CRTL line to limit the current to 500μA is
recommended to for such cases as:
• an accidentally requested acknowledge, or
• to protect the internal ACKN-MOSFET.
UNDERVOLTAGE LOCKOUT
An undervoltage lockout prevents operation of the device at input voltages below typical 2.2V. When the input
voltage is below the undervoltage threshold, the device is shutdown and the internal switch FET is turned off. If
the input voltage rises by undervoltage lockout hysteresis, the IC restarts.
THERMAL SHUTDOWN
An internal thermal shutdown turns off the device when the typical junction temperature of 160°C is exceeded.
The device is released from shutdown automatically when the junction temperature decreases by 15°C.
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