CS5451A
1. PIN DESCRIPTION
Serial Clock Output
SCLK 1
Serial Data Output
SDO 2
Frame Sync
FSO 3
Serial Port Enable
SE 4
Current Input Gain
GAIN 5
Analog Ground AGND 6
Reference Input VREFIN 7
Reference Output VREFOUT 8
Positive Analog Supply
VA+ 9
Negative Analog Supply
VA - 10
Differential Voltage Input 3 VIN3+ 11
Differential Voltage Input 3
VIN3- 12
Differential Current Input 3
IIN3+ 13
Differential Current Input 3
IIN3- 14
28 VD+ Digital Supply
27 DGND Digital Ground
26 CPD Charge Pump Drive
25 XIN Master Clock
24 RESET Reset
23 OWRS Output Word Rate Select
22 VIN1+ Differential Voltage Input 1
21 VIN1- Differential Voltage Input 1
20 IIN1+ Differential Current Input 1
19 IIN1- Differential Current Input 1
18 VIN2+ Differential Voltage Input 2
17 VIN2- Differential Voltage Input 2
16 IIN2+ Differential Current Input 2
15 IIN2- Differential Current Input 2
Clock Generator
Master Clock Input
25 XIN - External clock signal or oscillator input.
Control Pins and Serial Data I/O
Serial Clock Output
1
SCLK - Serial port clock signal that determines the output data rate for SDO pin. Rate of SCLK is
dependent on the XIN frequency and state of OWRS pin.
Serial Data Output
2 SDO -Serial port data output pin. Data will be output at a rate defined by SCLK.
Frame Sync
3 FSO - Framing signal indicates when data samples are about to be transmitted on the SDO pin.
Serial Port Enable
4 SE - When SE is low, the output pins of the serial port are tri-stated.
Current Input Gain
5
GAIN - A logic high sets current channel gain to 1, a logic low sets the gain to 20. If no connection
is made to this pin, it will default to logic low level (through internal 200 k resistor to DGND).
Output Word Rate Select
OWRS - A logic low sets the output word rate (OWR) to XIN/2048 (Hz). A logic high sets the
23 OWR to XIN/1024 (Hz). If no connection is made to this pin, then OWRS will default to logic low
level (through internal 200 k resistor to DGND).
Reset
24 RESET - Low activates Reset, all internal registers are set to their default states.
Analog Inputs/Outputs
Voltage Reference Input
7 VREFIN - The input to this pin establishes the voltage reference for the on-chip modulator.
Voltage Reference Output
8
VREFOUT - The on-chip voltage reference output. The voltage reference has a nominal magni-
tude of 1.2 V and is referenced to the AGND pin on the converter.
Differential Voltage Inputs
11,12 VIN3+, VIN3- - Differential analog input pins for the voltage channel 3.
18,17 VIN2+, VIN2- - Differential analog input pins for the voltage channel 2.
22,21 VIN1+, VIN1- - Differential analog input pins for the voltage channel 1.
Differential Current Inputs
13,14 IIN3+, IIN3- - Differential analog input pins for the current channel 3.
16,15 IIN2+, IIN2- - Differential analog input pins for the current channel 2.
20,19 IIN1+, IIN1- - Differential analog input pins for the current channel 1.
Power Supply Connections
Analog Ground
6 AGND - Analog ground.
Positive Analog Supply
9 VA+ - The positive analog supply. Typical +3 V ±10% relative to AGND.
Negative Analog Supply
10 VA- - The negative analog supply. Typical -2 V ±10% relative to AGND.
Charge Pump Drive
26
CPD - Designed to drive external charge pump circuitry that will produce a negative analog sup-
ply (VA-)voltage.
Digital Ground
27 DGND - Digital Ground.
Positive Digital Supply
28 VD+ - The positive digital supply. Typical +3 V ±10% relative to AGND.
DS635F4
3