MAX19711 Datasheet, PDF (25/36 Pages) Maxim Integrated Products – 10-Bit, 11Msps, Full-Duplex Analog Front-End

10-Bit, 11Msps, Full-Duplex
Analog Front-End
In FAST Rx mode, the Tx path (DAC core and Tx filter) is
powered on. The Tx path outputs are set to midscale. In
this mode, the Tx DAC input bus is disconnected from
the DAC core and DA0–DA9 are internally pulled to
OV_DD. The Rx ADC digital bus is active and the ADC
core is fully operational.
In FAST mode, the switching time from Tx to Rx, or Rx to
Tx is minimized because the converters are on and do
not have to recover from a power-down state. In FAST
mode, the switching time from Rx to Tx is 1µs and Tx to
Rx is 0.1µs. Power consumption is higher in FAST mode
because both Tx and Rx cores are always on.
In SLOW Tx mode, the Rx ADC core is powered off and
the ADC digital outputs AD0–AD9 are tri-stated. The Tx
DAC digital bus is active and the DAC core is fully oper-
ational. In SLOW Rx mode, the Tx DAC core is powered
off. The Tx path outputs are set to 0. In SLOW Rx mode,
the Tx DAC input bus is disconnected from the DAC
core and DA0–DA9 are internally pulled to OV_DD. The
Rx ADC digital bus is active and the ADC core is fully
operational. The switching times for SLOW modes are
5µs for Rx to Tx and 6.8µs for Tx to Rx.
Power consumption in SLOW Tx mode is 34.5mW, and
24.3mW in SLOW Rx mode. Power consumption in FAST
Tx mode is 42.3mW, and 41.4mW in FAST Rx mode.
FD Mode
The MAX19711 features an FD mode, which is ideal for
applications supporting frequency-division duplex. In
FD mode, both Rx ADC and Tx DAC, as well as their
respective digital buses, are active and the device can
receive and transmit simultaneously. Switching from FD
mode to Rx (0.1µs) or Tx (1µs) modes is fast since
the on-board converters are already powered.
Consequently, power consumption in this mode is the
maximum of all operating modes. In FD mode the
MAX19711 consumes 42.75mW.
Wake-Up Function
The MAX19711 uses the SPI interface to control the
operating modes of the device including the shutdown
and wake-up functions. Once the device has been
placed in shutdown through the appropriate SPI com-
mand, the first pulse on CS/WAKE performs a wake-up
function. At the first rising edge of CS/WAKE, the
MAX19711 is forced to a preset operating mode deter-
mined by the WAKEUP-SEL register. This mode is
termed the wake-up state. If the WAKEUP-SEL register
has not been programmed, the wake-up state for the
MAX19711 is FD mode by default (Tables 6, 12). The
WAKEUP-SEL register cannot be programmed with W2
= 0, W1 = 0, and W0 = 0. If this value is inadvertently
written to the device, it is ignored and the register con-
tinues to store its previous value. Upon wake-up, the
MAX19711 enters the power mode determined by the
WAKEUP-SEL register, however, all other settings (Tx
DAC offset, Tx DAC common-mode voltage, aux-DAC
settings, aux-ADC state) are restored to their values
prior to shutdown.
The only SPI line that is monitored by the MAX19711
during shutdown is CS/WAKE. Any information transmit-
ted to the MAX19711 concurrent with the CS/WAKE
wake-up pulse is ignored.
SPI Timing
The serial digital interface is a standard 3-wire connection
CS/WAKE, SCLK, DIN) compatible with SPI/QSPI™/
MICROWIRE/DSP interfaces. Set CS/WAKE low to enable
the serial data loading at DIN or output at DOUT.
Following a CS/WAKE high-to-low transition, data is shift-
ed synchronously, most significant bit first, on the rising
edge of the serial clock (SCLK). After 16 bits are loaded
into the serial input register, data is transferred to the
latch when CS/WAKE transitions high. CS/WAKE must
transition high for a minimum of 80ns before the next write
QSPI is a trademark of Motorola, Inc.
t_CSW
CS/WAKE
SCLK
DIN
t_CSS
t_CP
t_CH
t_CL
t_DS
t_DH
MSB
t_CS
LSB
Figure 7. Serial-Interface Timing Diagram
______________________________________________________________________________________ 25