Datasheet

20
LTC1850/LTC1851
18501f
APPLICATIO S I FOR ATIO
WUUU
CONVST
CS = RD = LOW
BUSY
DATA DATA (N – 1) DATA N
1851 F06
t
13
t
6
t
6
t
7
t
8
t
CONV
t
5
Figure 6. Mode 1b CONVST Starts a Conversion. Data is Read by RD
CONVST
CS = RD = LOW
BUSY
t
6
t
7
DATA DATA (N – 1) DATA N
1851 F05
t
5
t
CONV
t
8
Figure 5. Mode 1a CONVST Starts a Conversion. Data Outputs Always Enabled
Figures 5 through 9 show several different modes of
operation. In modes 1a and 1b (Figures 5 and 6),
CS and RD are both tied low. The falling edge of
CONVST starts the conversion. The data outputs are
always enabled and data can be latched with the
BUSY rising edge. Mode 1a shows operation with a narrow
logic low CONVST pulse. Mode 1b shows a narrow logic
high CONVST pulse.
In mode 2 (Figure 7), CS is tied low. The falling edge of
CONVST signal again starts the conversion. Data outputs
are in three-state until read by the MPU with the
RD signal. Mode 2 can be used for operation with a shared
MPU databus.
In slow memory and ROM modes (Figures 8 and 9), CS is
tied low and CONVST and RD are tied together. The MPU
starts the conversion and reads the output with the RD
signal. Conversions are started by the MPU or DSP (no
external sample clock).