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CS5451A

Six-channel, Delta-sigma Analog-to-digital Converter

Features

• Synchronous Sampling

• On-chip 1.2 V Reference (25 ppm/°C typ.)

• Power Supply Configurations:

- VA+ = +3 V; VA- = -2 V; VD+ = +3 V

- Supply Tolerances: ±10%

• Power Consumption

- 23 mW Typical at VD+ = +3 V

• Simple Four-wire Serial Interface

• Charge pump driver output generates

negative power supply.

• Ground-referenced Bipolar Inputs

Description

The CS5451A is a highly integrated delta-sigma ( an-

alog-to-digital converter (ADC) developed for the power

measurement industry. The CS5451A combines six 

ADCs, decimation filters, and a serial interface on a sin-

gle chip. The CS5451A interfaces directly to a current

transformer or shunt to measure current, and to a resis-

tive divider or transformer to measure voltage. The

product features a serial interface for communication

with a microcontroller or DSP. The product is initialized

and fully functional upon reset, and includes a voltage

reference.

ORDERING INFORMATION:

See page 13.

VREFIN

VREFOUT

IIN1+

IIN1-

VIN1+

VIN1-

VIN2+

VIN2-

VIN3+

VIN3-

IIN2+

IIN2-

IIN3+

IIN3-

VA+

VD+

AGND

FSO

SDO

SCLK

Voltage

Reference

Serial

Interface

RESET

Decimation Filter

x1, 20

4th Order  Modulator

x1, 20

4th Order  Modulator

GAIN

CPD

OWRS

XIN

DGND

VA-

Clock

Pulse Output

Regulator

APR ‘11

DS635F4

Summary of content (14 pages)

PAGE 1
CS5451A Six-channel, Delta-sigma Analog-to-digital Converter Features Description • Synchronous Sampling • On-chip 1.2 V Reference (25 ppm/°C typ.) • Power Supply Configurations: The CS5451A is a highly integrated delta-sigma ( analog-to-digital converter (ADC) developed for the power measurement industry. The CS5451A combines six  ADCs, decimation filters, and a serial interface on a single chip.
PAGE 2
CS5451A TABLE OF CONTENTS 1. PIN DESCRIPTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. CHARACTERISTICS AND SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. THEORY OF OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4. FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PAGE 3
CS5451A PIN DESCRIPTION Serial Clock Output SCLK 1 28 VD+ Digital Supply Serial Data Output SDO 2 27 DGND Digital Ground Frame Sync FSO 3 26 CPD Charge Pump Drive Serial Port Enable SE 4 25 XIN Master Clock Current Input Gain GAIN 5 24 RESET Reset Analog Ground AGND 6 23 OWRS Output Word Rate Select Reference Input VREFIN 7 22 VIN1+ Differential Voltage Input 1 Reference Output VREFOUT 8 21 VIN1- Differential Voltage Input 1 20 IIN1+ Differential Current Input
PAGE 4
CS5451A 2. CHARACTERISTICS AND SPECIFICATIONS RECOMMENDED OPERATING CONDITIONS Parameter DC Power Supplies Positive Digital Positive Analog Negative Analog Voltage Reference Input Symbol Min Typ Max Unit VD+ VA+ VA- 2.7 2.7 -2.2 3.0 3.0 -2.0 3.3 3.3 -1.8 V V V VREF+ - 1.2 - V ANALOG CHARACTERISTICS • • • • Min/Max characteristics and specifications are guaranteed over all Operating Conditions.
PAGE 5
CS5451A ANALOG CHARACTERISTICS (continued) Parameter Symbol Min Typ Max Unit PSCA PSCD PSCD - 4.0 5.0 1.0 5.3 6.3 1.5 mA mA mA PC PC - 27 23 35 31 mW mW PSRR PSRR PSRR 50 50 60 65 90 - dB dB dB Power Supplies Power Supply Currents IA+ ID+ with CPD Typical VA+ = VD+ = +3 V; VA- = -2 V ID+ without CPD Power Consumption (Note 2) With CPD Without CPD Power Supply Rejection 50, 60 Hz (Note 3) 50, 60 Hz (Note 3) (DC) Voltage Channel Current Channel Notes: 1.
PAGE 6
CS5451A SWITCHING CHARACTERISTICS • • • • Min/Max characteristics and specifications are guaranteed over all Operating Conditions. Typical characteristics and specifications are measured at nominal supply voltages and TA = 25 °C. VA+ = VD+ = 3 V ±10%; VA- = -2 V ±10%; AGND = DGND = 0 V. All voltages with respect to 0 V. Logic Levels: Logic 0 = 0 V, Logic 1 = VD+ Symbol Min Typ Max Unit Rise Times (Note 6) Parameter Any Digital Input (except XIN) XIN only Any Digital Output trise - 50 1.
PAGE 7
CS5451A ABSOLUTE MAXIMUM RATINGS WARNING: Operation at or beyond these limits may result in permanent damage to the device. Normal operation is not guaranteed at these extremes. Parameter Symbol Min Typ Max Unit DC Power Supplies Positive Digital Positive Analog Negative Analog VD+ VA+ VA- -0.3 -0.3 -2.5 - +3.5 +3.5 -0.
PAGE 8
CS5451A 3. THEORY OF OPERATION The CS5451A is a six-channel analog-to-digital converter (ADC) followed by a serial interface that allows communication with a target device. The analog inputs are structured for 3-phase power meter applications, with three dedicated voltage and current channels. Figure 2 illustrates the CS5451A typical inputs and power supply connections.
PAGE 9
CS5451A 4. 4.1 FUNCTIONAL DESCRIPTION Analog Inputs The CS5451A is equipped with six fully differential input channels. The inputs VIN(1-3) and IIN(1-3) are designated as the voltage and current channel inputs, respectively. The full-scale differential input voltage for the current and voltage channel is 800 mVP (gain = 1x). 4.1.1 Voltage Channel 800mV P -----------------  565.69mVRMS 2 which is approximately 70.7% of maximum peak voltage.
PAGE 10
CS5451A 96 SCLKs SCLK FSO 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 15 14 SDO [ Low ] Channel 1 ( V ) Channel 1 ( I ) ... ... ... ... ... ... 3 2 1 0 Ch. 2 ( V )... Ch. 2 ( I ) ... Ch. 3 ( V ) ... Ch. 3 ( I ) ... [ Low ] Figure 3. One Data Frame When data is not being transferred SCLK is held low. (see Figure 3.) RESET is activated, all internal registers are set to a default state. The framing signal (FSO) output is normally low.
PAGE 11
CS5451A shifting of the analog inputs. The CPD pin and capacitor C1 provide the necessary analog supply current as shown in Figure 5. The Schottky diodes D1 and D2 are chosen for their low forward voltages and high-speed capabilities. The capacitor C2 provides the required charge storage and bypassing of the negative supply. The CPD output signal provides the charge pump driver signal. The frequency of the charge pump driver signal is synchronous to XIN. The nominal average frequency is 1 MHz.
PAGE 12
CS5451A 5. PACKAGE DIMENSIONS 28L SSOP PACKAGE DRAWING N D E11 A2 E A  e b2 SIDE VIEW A1 END VIEW L SEATING PLANE 1 2 3 TOP VIEW INCHES DIM A A1 A2 b D E E1 e L  MIN -0.002 0.064 0.009 0.390 0.291 0.197 0.022 0.025 0° NOM -0.006 0.069 -0.4015 0.307 0.209 0.026 0.0354 4° MILLIMETERS MAX 0.084 0.010 0.074 0.015 0.413 0.323 0.220 0.030 0.041 8° MIN -0.05 1.62 0.22 9.90 7.40 5.00 0.55 0.63 0° NOM -0.13 1.75 -10.20 7.80 5.30 0.65 0.90 4° NOTE MAX 2.13 0.25 1.88 0.38 10.50 8.20 5.60 0.75 1.
PAGE 13
CS5451A 6. ORDERING INFORMATION Model CS5451A-ISZ (lead free) Temperature Package -40 to +85 °C 28-pin SSOP 7. ENVIRONMENTAL, MANUFACTURING, & HANDLING INFORMATION Model Number CS5451A-ISZ (lead free) Peak Reflow Temp MSL Rating* Max Floor Life 260 °C 3 7 Days * MSL (Moisture Sensitivity Level) as specified by IPC/JEDEC J-STD-020.
PAGE 14
CS5451A 8. REVISION HISTORY Revision Date Changes A1 JUL 2003 Initial Release PP1 OCT 2003 Initial release for Preliminary Product Information F1 FEB 2005 Update electrical specifications w/ most-current characterization data. F2 AUG 2005 Update electrical specifications w/ most-current characterization data. Added MSL data. F3 FEB 2010 Corrected typical input sampling rate from XIN/4 to XIN/8 (Hz). F4 APR 2011 Removed lead-containing (Pb) device ordering information.