Cirrus Logic CS4461 User Manual
CS4461
Multi-Bit A/D for Class-D Real-Time PSR Feedback
Features
z Advanced Multi-bit Delta-Sigma Architecture
z Real-time Feedback of Power Supply
Conditions (AC and DC)
z Filterless Digital Output Resulting in Very Low
Signal Delay
z 135 mW Power Consumption
z Supports Logic Levels Between 3.3 V and
5.0 V
z Differential Analog Architecture
z Modulator Overflow Detection
z Interfaces Directly to the CS44800/CS44600
Class-D PWM Modulator
z Multi-bit Conversion at up to 7.5 MHz
z Delivers Modulated Data Over 2-Wire Interface
General Description
The CS4461 is a complete analog-to-digital converter
for class-D real-time power supply rejection (PSR) feedback. It performs sampling and analog-to-digital
conversion, generating digital data for input to a
class-D modulator with real-time PSR feedback
capabilities.
The CS4461 uses a 5th-order, multi-bit delta-sigma
modulator followed by output data formatting. The ADC
uses a differential architecture which provides excellent
noise rejection.
The CS4461 feeds back the AC and DC voltage components and is ideal for class-D audio systems requiring
high power supply rejection.
The CS4461 is available in a 24-pin TSSOP package in
both Commercial (-10° to +70° C) and Automotive
grade (-40° to +85° C). The CDB44800 Customer Demonstration board is also available for device evaluation
and implementation suggestions. Please see “Ordering
Information” on page 11 for complete details.
FILT+
AIN+
AIN-
Voltage Reference
S/H
http://www.cirrus.com
VQ
REFGND
+
-
PSR_RESET
LP Filter
DAC
5.0 V
(VA)
Copyright © Cirrus Logic, Inc. 2005
(All Rights Reserved)
∆Σ
GND
PSR_EN
3.3 V to 5.0 V
(VDP)
Output Data
Formatting
OVERFLOW
PSR_MCLK
PSR_SYNC
PSR_DATA
SEPTEMBER '05
DS650F1
TABLE OF CONTENTS
1. CHARACTERISTICS AND SPECIFICATIONS ..................................................................................... 3
2. PIN DESCRIPTIONS ............................................................................................................................. 6
3. TYPICAL CONNECTION DIAGRAM .................................................................................................... 7
4. APPLICATIONS .................................................................................................................................... 8
4.1 Digital Connections ......................................................................................................................... 8
4.2 Analog Connections ....................................................................................................................... 8
4.3 Power-Up Sequence ...................................................................................................................... 9
4.4 Overflow Detection ......................................................................................................................... 9
4.5 Grounding and Power Supply Decoupling ......................................................................................9
5. PACKAGE DIMENSIONS ................................................................................................................. 10
6. ORDERING INFORMATION ............................................................................................................... 11
7. REVISION HISTORY ........................................................................................................................... 11
LIST OF FIGURES
Figure 1. Typical Connection Diagram......................................................................................................... 7
Figure 2. CS4461 Recommended Analog Input Buffer................................................................................8
CS4461
2 DS650F1
CS4461
1. CHARACTERISTICS AND SPECIFICATIONS
(All Min/Max characteristics and specifications are guaranteed over the Specified Operating Conditions. Typical
performance characteristics and specifications are derived from measurements taken at typical supply voltages
and T
= 25°C.)
A
SPECIFIED OPERATING CONDITIONS
(GND = 0 V, all voltages with respect to 0 V.)
Parameter Symbol Min Typ Max Unit
DC Power Supplies: Positive Analog
Positive DigitalVAVDP
Ambient Operating Temperature Commercial (-CZZ)
Automotive (-DZZ)
T
AC
T
AA
4.75
3.1
-10
-40
5.0
3.3
5.25
5.25
-
-
+70
+85
V
V
°C
°C
ABSOLUTE MAXIMUM RATINGS
(GND = 0 V, All voltages with respect to ground.) (Note 1)
Parameter Symbol Min Max Units
DC Power Supplies: Analog
DigitalVAVDP
Input Current (Note 2) I
Analog Input Voltage (Note 3) V
Digital Input Voltage (Note 3) V
Ambient Operating Temperature (Power Applied) T
Storage Temperature T
in
IN
IND
A
stg
-0.3
-0.3
- ±10 mA
GND - 0.7 VA + 0.7 V
-0.7 VDP + 0.7 V
-50 +95 °C
-65 +150 °C
+6.0
+6.0
V
V
Notes:
1. Operation beyond these limits may result in permanent damage to the device.
Normal operation is not guaranteed at these extremes.
2. Any pin except supplies. Transient currents of up to ±100 mA on the analog input pins will not cause
SCR latch-up.
3. The maximum over/under voltage is limited by the input current.
DS650F1 3
CS4461
DC ELECTRICAL CHARACTERISTICS
(GND = 0 V, all voltages with respect to ground. PSR_MCLK=12.288 MHz)
Parameter Symbol Min Typ Max Unit
Power Supply Current VA
(Normal Operation) VDP = 5.0 V
VDP = 3.3 V
Power Supply Current VA
(Power-Down Mode) (Note 4) VDP = 5.0 V
Power Consumption
(Normal Operation) VDP = 5.0 V
VDP = 3.3 V
(Power-Down Mode) VDP = 5.0 V
ADC Power Supply Rejection Ratio (1 kHz) (Note 5) PSRR - 65 - dB
VQ Nominal Voltage
Output Impedance
Maximum allowable DC current source/sink
FILT+ Nominal Voltage
Output Impedance
Maximum allowable DC current source/sink
Notes:
I
A
I
D
I
D
I
A
I
D
-
-
-
-
-
-
-
-
-
-
-
-
-
-
17.5
22
14.5
2
2
198
135
20
2.5
25
0.01
5
18
0.01
21
26
17
-
-
235
161
-
-
-
-
-
-
-
mW
mW
mW
mW
mA
mA
mA
mA
mA
V
kΩ
mA
V
kΩ
mA
4. Power Down Mode is defined as PSR_RESET
= Low with all clocks and data lines held static.
5. Valid with the recommended capacitor values on FILT+ and VQ as shown in the Typical Connection
Diagram.
DIGITAL CHARACTERISTICS
Parameter Symbol Min Typ Max Units
High-Level Input Voltage (% of VDP) V
Low-Level Input Voltage (% of VDP) V
High-Level Output Voltage at I
Low-Level Output Voltage at Io = 100 µA (% of VDP) V
OVERFLOW
Input Leakage Current I
Current Sink I
= 100 µA (% of VDP) V
o
OVERFLOW
IH
IL
OH
OL
in
70% - - V
--30%V
70% - - V
--15%V
--4.0mA
--±10 µA
THERMAL CHARACTERISTICS
Parameter Symbol Min Typ Max Unit
Allowable Junction Temperature - - 135
Junction to Ambient Thermal Impedance θ
JA
-70 -
°C
°C/W
4 DS650F1
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