Atmel ATA6264 18. Voltage/Current Sources (IASGx Sources)

58

4929B–AUTO–01/07

ATA6264 [Preliminary]

18. Voltage/Current Sources (IASGx Sources)

For a variable resistance measurement and especially for buckle-switch detection, five constant

voltage sources, switchable between two different voltages (V1 and V2) are implemented. The

current delivered by these voltage sources is mirrored by a factor of 1 / 10 or 1/ 15 to the pin

ISENS and causes a voltage drop at the external resistor connected to this pin. This voltage

drop can be measured at pin UZP by choosing the corresponding AMUX command. The exter-

nal resistor at pin IASGx can be calculated using the following formulas:

or

The current through pin IASGx is internally limited to a value between IIASGx = –150mA and

–50 mA. If the voltage at pin ISENS becomes higher than VVPERI, the voltage at pin IASG and,

consequently, the current at pin IASGx is reduced until VISENS =V

VPERI. This function can be

used to reduce the current limitation of pin IASGx to values lower than the internal limit by choos-

ing an adequate external resistor at pin ISENS. In this case, the maximum current through pin

IASGx can be calculated as:

or

For high accuracy, the IASGx current needs to be between 0.5 mA and 40 mA, and the maxi-

mum ISENS voltage must be < VPERI– 40%. Under a clamping condition, the voltage at pin

ISENS is clamped to VPERI + 5%. Calculation of the resistor at pin ISENS:

In applications with one or more unused IASG channels, the IASG pins can be used as mea-

surement inputs. The five IASG pins are connected to the analog multiplexer block via different

dividers. Voltages applied to these IASG pins can be measured at the UZP pin, selected via SPI

commands.

RIASGx

RISENS

10

------------------ VV1 VV2

–

VISENS1 VISENS2

–

-----------------------------------------------

×=

RIASGx

RISENS

15

------------------ VV1 VV2

–

VISENS1 VISENS2

–

-----------------------------------------------

×=

IIASGxlim 10 VVPERI

RISENS

------------------

×=

IIASGxlim 15 VVPERI

RISENS

------------------

×=

RSENS 0.96 VPERI

×CR1

IASGmax

--------------------

×=

Contents

Main Features 1. Description Airbag Power Supply IC ATA6264 Preliminary ATA6264 [Preliminary] Figure 1-1. Block Diagram V VSAT V 1.1 Block Description ATA6264 [Preliminary] 2. Pin Configuration Figure 2-1. Pinning QFP44 Table 2-1. Pin Description ATA6264 [Preliminary] 3. Absolute Maximum Ratings 3. Absolute Maximum Ratings (Continued) 4. Functional Range 4.1 Protection Against Substrate Currents 5. Supply Currents 5.1 Discharger Circuit 5.2 Initial Programming of the ATA6264 Page Page 4929BAUTO01/07 5.3 Start-up and Power-down Procedure V V V V Page Page Page 6. Power Supply Sequencing Figure 6-2. Block Diagram Power Supply Sequencing V V V VCORE - Regulator V 7. Charge Pump VEVZ = 5.5V to 40V or VK30 = 5.5V to 40V, VK15 > 3V, VVINT = 3.7V to 5.47V VVSAT, VVPERI and VVCORE are within functional range limits, Tj = 40C to 150C Table 7-1. Electrical Characteristics Charge Pump 8. GKEY Function Figure 8-2. Application With High Current Switch (GKEY Function Not Used) VK15 = 3V to 40V, VK30 = 3.85V to 40V VEVZ, VSAT, VPERI and VCORE are within functional range limits, Tj = 40C to 150C Table 8-2. Electrical Characteristics GKEY Function 9. EVZ Step-up Regulator Page ATA6264 [Preliminary] VK15 = 3V to 40V, VK30 = 5V to 40V, CGEVZ = 200 pF to 2 nF, VINT = 3.7V to 5.47V VSAT, VPERI and VCORE are within functional range limits, Tj = 40C to 150C Table 9-1. Electrical Characteristics EVZ Step-up Regulator Table 9-1. Electrical Characteristics (Continued) EVZ Step-up Regulator Table 9-1. Electrical Characteristics (Continued)EVZ Step-up Regulator 10. VSAT Power Supply VEVZ = 5.5V to 40V, VCP > VEVZ + 7V, VINT = 3.7V to 5.45V VK30, VPERI and VCORE are within functional range limits, Tj = 40C to +150C Table 10-1. Electrical Characteristics VSAT Power Supply Table 10-1. Electrical Characteristics (Continued) VSAT Power Supply 11. VPERI Power Supply VSAT > 7.5V, VINT = 3.7V to 5.47V, VCORE < VPERI + 0.3V VK30, VEVZ and VCORE are within functional range limits, Tj = 40C to 150C Table 11-1. Electrical Characteristics VPERI Power Supply 12. VCORE Power Supply VEVZ = 5.5V to 40V or VK30 = 5.5V to 40V, VCP > VEVZ + 7V or VCP > VK30 + 7V, VPERI >V VSAT is within functional range limits, Tj = 40C to 150C Table 12-1. Electrical Characteristics VCORE Power Supply Page Table 12-1. Electrical Characteristics (Continued) VCORE Power Supply 13. USP Comparator for General Purpose 14. Reference Voltage and Reference Current Generation 15. Reset Function (Pin RESQ and Pin RESQ2) Figure 15-2. Functional Principle of RESQ, RESQ2 Page Figure 15-4. Application Example VEVZ = 5.5V to 40V, VPERI = 1V to 5.5V, VINT = 3.7V to 5.47V VK30, VSAT, and VCORE are within functional range limits, Tj = 40C to 150C Table 15-1. Reset Truth Table Table 15-2. Electrical Characteristics Reset Function (Pin RESQ and Pin RESQ2) Table 15-2. Electrical Characteristics (Continued) Reset Function (Pin RESQ and Pin RESQ2) 16. Watchdog Function Page Page Figure 16-4. Watchdog Trigger Functional Principle (Unsuccessful Watchdog Trigger) Page VPERI > Reset threshold, VCORE > Reset threshold VK30, VEVZ and VVSAT are within functional range limits, Tj = 40C to 150C Table 16-2. Electrical Characteristics Watchdog Function Figure 16-5. Watchdog Trigger 17. LIN/ISO 9141 Interfaces Table 17-1. Electrical Characteristics LIN/ISO 9141 Interfaces Table 17-1. Electrical Characteristics (Continued)LIN/ISO 9141 Interfaces Figure 17-2. Timing LIN/ISO 9141 Interface Table 17-1. Electrical Characteristics (Continued)LIN/ISO 9141 Interfaces 18. Voltage/Current Sources (IASGx Sources) Figure 18-1. Functional Principle of the IASG Interface - VK30 and VVSAT are within functional range limits, Tj = 40C to 150C As defined in Section 4. Functional Range on page 8, CIASGx 10 nF and 825RISENS 5k + Table 18-1. Electrical Characteristics Voltage/Current Sources (IASGx Sources) Table 18-1. Electrical Characteristics (Continued)Voltage/Current Sources (IASGx Sources) ATA6264 [Preliminary] 19. AMUX (Analog Multiplexer for Voltage Measurements) Table 19-1. Electrical Characteristics AMUX (Analog Multiplexer for Voltage Measurements) ATA6264 [Preliminary] 20. UZP Buffer Table 20-1. Electrical Characteristics UZP Buffer 21. Chip Temperature Measurement 22. Serial Interface Commands 22.1 Overview Table 22-1. Electrical Characteristics (Continued) SerialInterface Commands Figure 22-1. Timing Serial Interface 22.2 Set Commands #16#1 Table 22-2. Set of Serial Interface Commands Table 22-3. Key Latch Commands Table 22-4. Watchdog Commands Table 22-5. Switch Commands Table 22-6. Initial Programming (IP Command) Table 22-7. Diagnosis Commands Page 22.3 Serial Interface Status Register Table 22-11. Information Provided by the Itemized Bits of the Status Register Page 23. Test Mode 24. Application Circuits Figure 24-1. Overview of a Typical Airbag System 4929BAUTO01/07 Figure 24-2. Typical Application Circuit ATA6264 26. Package Information 25. Ordering Information Page 28. Table of Contents Page Atmel Corporation Atmel Operations Regional Headquarters Europe Asia Japan