SGS Thomson Microelectronics STPM11, STPM14ATR Datasheet

Single phase energy metering IC with pulsed output

Feature summary

■ Ripple free active energy pulsed output

■ Direct stepper counter drivers

■ Shunt, current transformer, Rogowsky coil

sensors

■ Live and neutral monitoring (STPM13/14)

■ Easy and fast digital calibration at only one

load point

■ No-load, negative power and tamper indicators

■ Integrated linear VREGS

■ RC (STPM11/13) or crystal oscillator

(STPM12/14)

■ Support 50÷60 HZ - IEC62052-11, IEC62053-

2X specification

■ Less than 0.1% error

Description

The STPM1x family is designed for effective measurement of active energy in a power line system using a Rogowski Coil, Current Transformer and Shunt sensors. This device is specifically designed to provide all the necessary features to implement a single phase energy meter without any other active component. The STPM1x device family consists, essentially, of two parts: the analog part and the digital part. The former, is composed of a preamplifier and first order ∑ ∆ A/D converter blocks, band gap

STPM11/12/13/14

and digital calibration

TSSOP20

voltage reference, low drop voltage regulator. The digital part is composed of a system control, oscillator, hard wired DSP and interface for calibration and configuration.

The calibration and configuration are done by OTP cells, that can be programmed through a serial interface. The configured bits are used for testing, configuration and calibration purposes. From two ∑ ∆ output signals coming from the analog section, a DSP unit computes the amount of consumed active energy. The active energy is available as a pulse frequency output and directly driven by a stepper counter. In the STPM1X an output signal with pulse frequency proportional to energy is generated. This signal is used in the calibration phase of the energy meter application allowing a very easy approach. When the device is fully configured and calibrated, a dedicated bit of OTP block can be written permanently in order to prevent accidental entry into test mode or changing any configuration bit.

Order code

Part number Package Packaging

STPM11ATR TSSOP20 (Tape & reel) 2500 parts per reel

STPM12ATR TSSOP20 (Tape & reel) 2500 parts per reel

STPM13ATR TSSOP20 (Tape & reel) 2500 parts per reel

STPM14ATR TSSOP20 (Tape & reel) 2500 parts per reel

March 2007 Rev. 3 1/43

www.st.com

STPM11/12/13/14

Contents

1 Schematic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5.1 Measurement error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5.2 ADC Offset error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5.3 Gain error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5.4 Power supply DC and AC rejection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5.5 Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

7 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.1 General operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.2 Analog inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.3

7.4 Period and line voltage measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

7.5 Single wire meter mode (STPM13/14 with Rogowsky coil sensor) . . . . . 16

7.6 Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

7.7 Load monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

7.8 Error detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

7.9 Tamper detection module (STPM13/14 only) . . . . . . . . . . . . . . . . . . . . . . 19

7.10 Phase compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

7.11 Clock generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

∑ ∆ A/D Converters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

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7.12 Resetting the STPM1X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

7.13 Energy to frequency conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

7.14 Driving a stepper motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

7.15 Configuring the STPM1X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

7.16 Mode signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

STPM11/12/13/14

7.17 CFGI: Configuration interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

8 Energy calculation algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

9 STPM1X Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

10 Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

11 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

12 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

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Schematic diagram STPM11/12/13/14

1 Schematic diagram

Figure 1. Block diagram

4/43

STPM11/12/13/14 Pin configuration

2 Pin configuration

Figure 2. Pin connections (top view)

Table 1. Pin description

Pln N° Symbol Type

(1)

Name and function

1 MON P O Output for Stepper’s node

2 MOP P O Output for Stepper’s node

3 SCS D IN Enable or disable configuration interface for device configuration.

10 I

11 I

12 I

13 V

14 V

DDD

OTP

DDA

IP1

IN1

IP2

IN2

A OUT 1.5V Output of internal low drop regulator which supplies the digital core.

GND Ground.

P IN Supply voltage.

P INr Supply voltage for OTP cells.

A OUT 3V Output of internal low drop regulator which supplies the analog part.

A IN Positive input of primary current channel

A IN Negative input of primary current channel

A IN Positive input of secondary current channel (STPM13/14 only)

A IN Negative input of secondary current channel (STPM13/14 only)

A IN Positive input of voltage channel

A IN Negative input of voltage channel

15 SYN-NP D I/O Negative power indicator. (Configuration interface)

16 CLKIN A IN Crystal oscillator input or resistor connection if RC oscillator is selected

17 CLKOUT A OUT Oscillator output (RC or crystal)

18 SCL/NLC D I/O No-load condition indicator. (Configuration interface)

19 SDATD D I/O Tamper detection indicator. (Configuration interface)

20 LED D O Pulsed output proportional to Active Energy

1. A: Analog, D: Digital, P: Power

5/43

Maximum ratings STPM11/12/13/14

3 Maximum ratings

Table 2. Absolute maximum ratings (See note)

Symbol Parameter Value Unit

DC Input voltage -0.3 to 6 V

Current on any pin (sink/source) ± 150 mA

Input voltage at digital pins (SCS, MOP, MON, SYN, SDATD, SCLNLC, LED)

Input voltage at analog pins (I

IP1

, I

IN1

, VIP, VIN) -0.7 to 0.7 V

IP2

IN2

-0.3 to V

+0.3 V

Input voltage at OTP pin -0.3 to 25 V

OTP

ESD Human body model (all pins) ± 3.5 kV

STG

Operating ambient temperature -40 to 85 °C

Junction temperature -40 to 150 °C

Storage temperature range -55 to 150 °C

Note: Absolute Maximum Ratings are those values beyond which damage to the device may

occur. Functional operation under these condition is not implied

Table 3. Thermal Data

Symbol Parameter Value Unit

thJA

1. This value is referred to single-layer PCB, JEDEC standard test board.

Thermal resistance junction-ambient 114.5

(1)

°C/W

6/43

STPM11/12/13/14 Electrical characteristics

4 Electrical characteristics

Table 4. Electrical characteristics

=5V, TA= 25°C, 2.2µF between V

between V

and VSS unless otherwise specified)

Symbol Parameter Test conditions Min. Typ. Max. Unit

Energy measurement accuracy

and VSS, 2.2µF between V

DDA

and VSS, 2.2µF

DDD

Effective bandwidth Limited by digital filtering 5 400 Hz

Over the dynamic range (5% to

Error Measurement error

1000% of the calibration power

0.1 %

value)

SNR Signal to noise ratio Over the entire bandwidth 52 db

Voltage signal: 200

PSRR

Power supply DC rejection

rms

/50Hz f

rms

=3.3V±10%, 5V±10%

CLK

= 4.194 MHz

0.2 %

/50Hz Current signal: 10

Voltage signal: 200

/50Hz Current signal: 10

PSRR

Power supply AC rejection

rms

=3.3V+0.2V

=5.0V+0.2V

/50Hz f

= 4.194 MHz

CLK

1@100Hz

rms

1@100Hz

rms

0.1 %

General section

Operating supply voltage 3.0 5.5 V

Supply current configuration registers cleared or device

locked (TSTD=1)

4 MHz, V

8 MHz, V

= 5V 3.5 4

= 5V 4.7 6

Increase of supply current per configuration bit, during

4 MHz, V

= 5V 120

programming

∆I

Increase of supply current per configuration bit with device

4 MHz, V

= 5V 2

locked

µA/bit

POR Power on reset on V

LINE

CLK

OTP

Analog supply voltage 2.85 3.0 3.15 V

DDA

Digital supply voltage 1.425 1.50 1.575 V

DDD

Oscillator clock frequency

Nominal line frequency 45 65 Hz

OTP programming voltage 14 20 V

OTP

OTP programming current per bit

OTP programming time per bit 100 300 µs

2.5 V

MDIV bit = 0 4.000 4.194 MHz

MDIV bit = 1 8.000 8.192 MHz

2.5 mA

7/43

Electrical characteristics STPM11/12/13/14

Table 4. Electrical characteristics

=5V, TA= 25°C, 2.2µF between V

between V

and VSS unless otherwise specified)

Symbol Parameter Test conditions Min. Typ. Max. Unit

and VSS, 2.2µF between V

DDA

and VSS, 2.2µF

DDD

LATCH

Current injection latch-up immunity

Analog Inputs (I

ADC

LEAK

MAX

SPL

OFF

ERR

ILV

Maximum input signal levels

A/D Converter bandwidth 10 KHz

A/D Sampling frequency F

Amplifier offset ±20 mV

VIP, VIN Impedance

IP1

Impedance

Current channels gain error ±10 %

Voltage channel leakage current -1 1 µA

Current channel leakage current

, V

IP1

IN1

, I

, V

IN1

IP2

300 mA

, I

, VIP, VIN)

IP2

IN2

Voltage channel -0.3 0.3 V

Gain 8X -0.15 0.15

Current channels

Gain 16X -0.075 0.075

Gain 24X -0.05 0.05

Gain 32X -0.035 0.035

/4 Hz

CLK

, V

IN2

Over the total operating voltage range

100 400 KΩ

100 KΩ

Channel disabled (PST=0 to 3; CH2 disabled if C disabled if C

SEL

=0; CH1

SEL

=1) or device off

-1 1 µA

Input enabled -10 10

Digital I/O Characteristics (SDA-TD, CLKIN, CLKOUT, SCS, SYN-NP, LED)

SDA-TD, SCS, SYN-NP, LED 0.75V

Input high voltage

CLKIN 1.5

SDA-TD, SCS, SYN-NP, LED 0.25V

Input low voltage

Output high voltage IO = -2mA VCC-0.4 V

Output low voltage IO = +2mA 0.4 V

Pull up current 15 µA

Transition time C

CLKIN 0.8

= 50pF 10 ns

LOAD

Power I/O Characteristics (MOP, MON)

Output high voltage IO = -14mA VCC-0.5 V

Output low voltage IO = +14mA 0.5 V

Transition time C

= 50pF 5 10 ns

LOAD

8/43

STPM11/12/13/14 Electrical characteristics

Table 4. Electrical characteristics

=5V, TA= 25°C, 2.2µF between V

between V

and VSS unless otherwise specified)

Symbol Parameter Test conditions Min. Typ. Max. Unit

Crystal oscillator (STPM12/14)

Input current on CLKIN ±1 µA

External resistor 1 4 MΩ

External capacitors 22 pF

CLK

Nominal output frequency

RC Oscillator (STPM11/13)

and VSS, 2.2µF between V

DDA

DDD

4 4.194

8 8.192

and VSS, 2.2µF

MHz

CLKIN

SET

JIT

Settling current

Settling resistor 12 kΩ

CLK

= 4 MHz

Frequency jitter 1 ns

40 60 µA

On chip reference voltage

Reference voltage 1.23 V

REF

Reference accuracy ±1 %

Temperature coefficient After calibration 30 50

Configuration interface timing

SCLKw

SYN

Data write speed 100 KHz

Data setup time 20 ns

Data hold time 0 ns

SYN-NP active width 2/f

CLK

Table 5. Typical external components

Function Component Parameter Value Tolerance Unit

Line voltage interface

Line current interface

Resistor divider

R to R ratio V

Current shunt

Current to voltage conversion ratio

Rogowsky coil 3 ±12%

=230V 1650 ±1%

RMS

=110V 830 ±1%

RMS

0.2 ±5%

ppm/°

V/V

mV/ACurrent transformer 30 ±12%

9/43

Terminology STPM11/12/13/14

5 Terminology

5.1 Measurement error

The error associated with the energy measured by STPM1X is defined as:

Percentage Error = [STPM1X (reading) - True Energy] / True Energy

5.2 ADC Offset error

This is the error due to the DC component associated with the analog inputs of the A/D converters. Due to the internal automatic DC offset cancellation, the STPM1X measurement is not affected by DC components in voltage and current channel. The DC offset cancellation is implemented in the DSP.

5.3 Gain error

The gain error is gain due to the signal channel gain amplifiers. This is the difference between the measured ADC code and the ideal output code. The difference is expressed as a percentage of the ideal code.

5.4 Power supply DC and AC rejection

This parameter quantifies the STPM1X measurement error as a percentage of the reading when the power supplies are varied. For the PSRR nominal supply voltages (3.3 and 5 V) is taken. A second reading is obtained with the same input signal levels when an ac (200 mV voltages. Any error introduced by this ac signal is expressed as a percentage of reading.

For the PSRR taken. A second reading is obtained with the same input signal levels when the supplies are varied ±10%. Any error introduced is again expressed as a percentage of the reading.

measurement, a reading at two nominal supply voltages (3.3 and 5V) is

/100 Hz) signal is introduced onto the supply

RMS

5.5 Conventions

The lowest analog and digital power supply voltage is named VSS which represents the system Ground (GND). All voltage specifications for digital input/output pins are referred to GND.

Positive currents flow into a pin. Sinking current means that the current is flowing into the pin and is positive. Sourcing current means that the current is flowing out of the pin and is negative.

The timing specifications of the signal treated by digital control are relative to CLK signal is provided by from the crystal oscillator of 4.194MHz nominal frequency or by the internal RC oscillator. An external source of 4.194MHz or 8.192MHz can be used.

measurement, a reading at two

OUT

. This

10/43

The timing specifications of signals of the CFGI interface are relative to the SCL-NLC, there is no direct relationship between the clock (SCL-NLC) of the CFGI interface and the clock of the DSP block.

A positive logic convention is used in all equations.

STPM11/12/13/14 Typical performance characteristics

6 Typical performance characteristics

Figure 3. Supply current vs supply voltage,

=25°C

Figure 5. RC Oscillator: Frequency jitter vs

temperature

Figure 4. RC Oscillator frequency vs V

R=12kΩ, T

=25°C

Figure 6. Analog voltage regulator: Line -

load regulation

Figure 7. Digital voltage regulator: Line - load

regulation

Figure 8. Voltage channel linearity at

different V

voltages

11/43

Typical performance characteristics STPM11/12/13/14

Figure 9. Power supply AC rejection vs V

Figure 11. Error over dynamic range gain

dependence

Figure 10. Power supply DC rejection vs V

Figure 12. Primary current channel linearity at

different V

Figure 13. Gain response of ∆Σ AD Converters Figure 14. Clock frequency vs external

12/43

f [MHz]

510152

resistor

CRC=0 CRC=1 CRC=2

R [kΩ]

STPM11/12/13/14 Theory of operation

7 Theory of operation

7.1 General operation

The STPM1X is able to perform active energy measurement (wide band or fundamental) in single-phase energy meter systems.

Due to the proprietary energy computation algorithm, STPM1X active energy is not affected by any ripple at twice the line frequency. The calibration is very easy and fast allowing calibration in only one point over the whole current range which allows saving time during the calibration phase of the meter. The calibration parameters are permanently stored in the OTP (one time programmable) cells, preventing calibration tampering.

Several functions are programmable using internal configuration bits accessible through the configuration interface. The most important configuration bits are two configuration bits called PST that allow the selection of the sensor and the gain of the input amplifiers.

The STPM1X is able to directly drive a stepper motor with the MOP and MON pins, and provides information on tamper, no-load and negative power.

Two kinds of active energy can be selected to be brought to the LED pin: the total active energy that includes all harmonic content up to 50 to the 1 energy.

harmonic. This last energy value is obtained by filtering the wide band active

7.2 Analog inputs

Input amplifiers

The STPM1X has one fully differential voltage input channel and one (STPM11/12) or two (STPM13/14) fully differential current input channels.

The voltage channel consists of a differential amplifier with a gain of 4. The maximum differential input voltage for the voltage channel is ±0.3V.

In STPM13/14, the two current channels are multiplexed (see tamper section for details) to provide a single input to a preamplifier with a gain of 4. The output of this preamplifier is connected to the input of a programmable gain amplifier (PGA) with possible gain selections of 2,4,6,8. The total gain of the current channels will be then 8, 16, 24, 32. The gain selections are made by writing to the gain configuration bits PST and it can be different for the two current channels. The maximum differential input voltage is dependent on the selected gain according to the

Table 6. Voltage channel

Tab le 6 .

harmonic and the active energy limited

Voltage channels Current channels

Gain Max Input voltage (V) Gain Max input voltage (V)

8X ±0.15

4 ±0.30

16X ±0.075

24X ±0.05

32X ±0.035

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