SNVS468L September   2006  – November 2015 LP3972

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Tables
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics
    6. 7.6  Electrical Characteristics: LDO RTC
    7. 7.7  Electrical Characteristics: LDOs 1 to 5
    8. 7.8  Electrical Characteristics: Buck Converters SW1, SW2, SW3
    9. 7.9  Electrical Characteristics: Backup Charger
    10. 7.10 Electrical Characteristics: I2C Compatible Serial Interface (SDA and SCL)
    11. 7.11 Logic Inputs and Outputs DC Operating Conditions
    12. 7.12 I2C Compatible Serial Interface Timing Requirements (SDA and SCL)
    13. 7.13 Power-On Timing Delays
    14. 7.14 Typical Characteristics
      1. 7.14.1 LDO Dropout Voltage vs Load Current Collect Data for all LDOs
      2. 7.14.2 Buck1 Output Efficiency vs. Load Current Varied From 1 mA to 1.5 A
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Buck Converter Operation
        1. 8.3.1.1 Circuit Operation
        2. 8.3.1.2 PWM Operation
          1. 8.3.1.2.1 Internal Synchronous Rectification
          2. 8.3.1.2.2 Current Limiting
        3. 8.3.1.3 PFM Operation
        4. 8.3.1.4 Soft Start
        5. 8.3.1.5 Low Dropout (LDO) Operation
        6. 8.3.1.6 Spread-Spectrum Feature
      2. 8.3.2 LP3972 Battery Switch Operation
    4. 8.4 Device Functional Modes
      1. 8.4.1 Start-Up Mode
      2. 8.4.2 Shutdown Mode
      3. 8.4.3 Standby Mode
      4. 8.4.4 Active Mode
    5. 8.5 Programming
      1. 8.5.1 LP3972 Reset Sequence
        1. 8.5.1.1 LP3972 Controls
          1. 8.5.1.1.1  Digital Interface Control Signals
          2. 8.5.1.1.2  Power Domain Enables
          3. 8.5.1.1.3  Power Domains Sequencing (Delay)
          4. 8.5.1.1.4  Power Supply Enable
          5. 8.5.1.1.5  Wake-up Functionality (PWR_ON, NTEST_JIG, SPARE and EXT_WAKEUP)
          6. 8.5.1.1.6  Internal Thermal Shutdown Procedure
          7. 8.5.1.1.7  Battery Switch and Backup Battery Charger
          8. 8.5.1.1.8  General Purpose I/O Functionality (GPIO1 And GPIO2)
          9. 8.5.1.1.9  Regulated Voltages OK
          10. 8.5.1.1.10 Thermal Management
          11. 8.5.1.1.11 Thermal Warning
          12. 8.5.1.1.12 LP3972 Thermal Flags Functional Diagram, Data from Initial Silicon
        2. 8.5.1.2 Initial Cold Start Power-On Sequence
        3. 8.5.1.3 Hardware Reset Sequence
        4. 8.5.1.4 Reset Sequence
      2. 8.5.2 I2C Compatible Interface
        1. 8.5.2.1 I2C Data Validity
        2. 8.5.2.2 I2C Start And Stop Conditions
        3. 8.5.2.3 Transferring Data
        4. 8.5.2.4 I2C Chip Address - 7h'34
          1. 8.5.2.4.1 Write Cycle
          2. 8.5.2.4.2 Read Cycle
        5. 8.5.2.5 Multi-Byte I2C Command Sequence
        6. 8.5.2.6 Incremental Register I2C Command Sequence
    6. 8.6 Register Maps
      1. 8.6.1 Serial Interface Register Selection Codes
        1. 8.6.1.1  System Control Status Register
          1. 8.6.1.1.1 System Control Register (SCR) 8h’07
          2. 8.6.1.1.2 System Control Register (SCR) 8h’07 Definitions
        2. 8.6.1.2  Output Voltage Enable Register 1
          1. 8.6.1.2.1 Output Voltage Enable Register 1 (OVER1) 8h’10
          2. 8.6.1.2.2 Output Voltage Enable Register 1 (OVER1) 8h’10 Definitions
        3. 8.6.1.3  Output Voltage Status Register
          1. 8.6.1.3.1 Output Voltage Status Register 1 (OVSR1) 8h’11
          2. 8.6.1.3.2 Output Voltage Status Register 1 (OVSR1) 8h’11 Definitions
        4. 8.6.1.4  Output Voltage Enable Register 2
          1. 8.6.1.4.1 Output Voltage Enable Register 2 (OVER2) 8h’12
          2. 8.6.1.4.2 Output Voltage Enable Register 2 (OVER2) 8h’12 Definitions
        5. 8.6.1.5  Output Voltage Status Register 2
          1. 8.6.1.5.1 Output Voltage Status Register 2 (OVSR2) 8h’13
          2. 8.6.1.5.2 Output Voltage Status Register 2 (OVSR2) 8h’13 Definitions
        6. 8.6.1.6  DVM Voltage Change Control Register 1
          1. 8.6.1.6.1 DVM Voltage Change Control Register 1 (VCC1) 8h’20
          2. 8.6.1.6.2 DVM Voltage Change Control Register 1 (VCC1) 8h’20 Definitions
        7. 8.6.1.7  Buck1 (VCC_APPS) Voltage 1
          1. 8.6.1.7.1 Buck1 (VCC_APPS) Target Voltage 1 Register (ADTV1) 8h’23
          2. 8.6.1.7.2 Buck1 (VCC_apps) Target Voltage 1 Register (ADTV1) 8h’23 Definitions
        8. 8.6.1.8  Buck1 (VCC_APPS) Target Voltage 2 Register
          1. 8.6.1.8.1 Buck1 (VCC_APPS) Target Voltage 2 Register (ADTV2) 8h’24
          2. 8.6.1.8.2 Buck1 (VCC_APPS) Target Voltage 2 Register (ADTV2) 8h’24 Definitions
        9. 8.6.1.9  Buck1 (VCC_APPS) Voltage Ramp Control Register
          1. 8.6.1.9.1 Buck1 (VCC_APPS) Voltage Ramp Control Register (AVRC) 8h’25
          2. 8.6.1.9.2 Buck1 (VCC_APPS) Voltage Ramp Control Register (AVRC) 8h’25 Definitions
        10. 8.6.1.10 VCC_comm Target Voltage 1 Dummy Register (CDTV1)
          1. 8.6.1.10.1 VCC_comm Target Voltage 1 Dummy Register (CDTV1) 8h’26 Write Only
        11. 8.6.1.11 VCC_COMM Target Voltage 2 Dummy Register (CDTV2)
          1. 8.6.1.11.1 VCC_COMM Target Voltage 2 Dummy Register (CDTV2) 8h’27 Write Only
        12. 8.6.1.12 LDO5 (VCC_SRAM) Target Voltage 1 Register
          1. 8.6.1.12.1 LDO5 (VCC_SRAM) Target Voltage 1 Register (SDTV1) 8h'29
          2. 8.6.1.12.2 LDO5 (VCC_SRAM) Target Voltage 1 Register (SDTV1) 8h’29 Definitions
        13. 8.6.1.13 LDO5 (VCC_SRAM) Target Voltage 2 Register
          1. 8.6.1.13.1 LDO5 (VCC_SRAM) Target Voltage 2 Register (SDTV2) 8h’2A
          2. 8.6.1.13.2 LDO5 (VCC_SRAM) Target Voltage 2 Register (SDTV2) 8h’2A Definitions
        14. 8.6.1.14 LDO1 (VCC_MVT) Target Voltage 1 Register (MDTV1)
          1. 8.6.1.14.1 LDO1 (VCC_MVT) Target Voltage 1 Register (MDTV1) 8h’32
          2. 8.6.1.14.2 LDO1 (VCC_MVT) Target Voltage 1 Register (MDTV1) 8h’32 Definitions
        15. 8.6.1.15 LDO1 (VCC_MVT) Target Voltage 2 Register
          1. 8.6.1.15.1 LDO1 (VCC_MVT) Target Voltage 2 Register (MDTV2) 8h’33
          2. 8.6.1.15.2 LDO1 (VCC_MVT) Target Voltage 2 Register (MDTV2) 8h’33 Definitions
        16. 8.6.1.16 LDO2 Voltage Control Register (L12VCR)
          1. 8.6.1.16.1 LDO2 Voltage Control Register (L12VCR) 8h’39
          2. 8.6.1.16.2 LDO2 Voltage Control Register (L12VCR) 8h’39 Definitions
        17. 8.6.1.17 LDO4 - LDO3 Voltage Control Register (L34VCR)
          1. 8.6.1.17.1 LDO4 - LDO3 Voltage Control Register (L34VCR) 8h’3A
          2. 8.6.1.17.2 LDO4 - LDO3 Voltage Control Register (L34VCR) 8h’3A Definitions
      2. 8.6.2 TI-Defined Control and Status Registers
        1. 8.6.2.1  System Control Register 1 (SCR1)
          1. 8.6.2.1.1 System Control Register 1 (SCR1) 8h’80
          2. 8.6.2.1.2 System Control Register 1 (SCR1) 8h’80 Definitions
        2. 8.6.2.2  System Control Register 2 (SCR2)
          1. 8.6.2.2.1 System Control Register 2 (SCR2) 8h’81
          2. 8.6.2.2.2 System Control Register 2 (SCR2) 8h’81 Definitions
        3. 8.6.2.3  Output Enable 3 Register (OEN3) 8h’82
        4. 8.6.2.4  Output Enable 3 Register (OEN3) 8h’82 Definitions
        5. 8.6.2.5  Status Register 3 (OSR3) 8h’83
        6. 8.6.2.6  Status Register 3 (OSR3) Definitions 8h’83
        7. 8.6.2.7  Logic Output Enable Register (LOER) 8h’84
        8. 8.6.2.8  Logic Output Enable Register (LOER) Definitions 8h’84
        9. 8.6.2.9  VCC_BUCK2 Target Voltage Register (B2TV) 8h’85
        10. 8.6.2.10 VCC_BUCK2 Target Voltage Register (B2TV) 8h’85 Definitions
        11. 8.6.2.11 BUCK3 Target Voltage Register (B3TV) 8h’86
        12. 8.6.2.12 BUCK3 Target Voltage Register (B3TV) 8h’86 Definitions
        13. 8.6.2.13 VCC_BUCK3:2 Voltage Ramp Control Register (B32RC)
          1. 8.6.2.13.1 VCC_BUCK3:2 Voltage Ramp Control Register (B32RC) 8h’87
          2. 8.6.2.13.2 Buck3:2 Voltage Ramp Control Register (B3RC) 8h’87 Definitions
        14. 8.6.2.14 Interrupt Status Register ISRA
          1. 8.6.2.14.1 Interrupt Status Register ISRA 8h’88
          2. 8.6.2.14.2 Interrupt Status Register ISRA 8h’88 Definitions
        15. 8.6.2.15 Backup Battery Charger Control Register (BCCR)
          1. 8.6.2.15.1 Backup Battery Charger Control Register (BCCR) 8h’89
          2. 8.6.2.15.2 Backup Battery Charger Control Register (BCCR) 8h’89 Definitions
        16. 8.6.2.16 Marvell PXA Internal 1 Revision Register (II1RR) 8h’8E
        17. 8.6.2.17 Marvell PXA Internal 1 Revision Register (II1RR) (Ii1rr) 8h’8E Definitions
        18. 8.6.2.18 Marvell PXA Internal 2 Revision Register (II1RR) 8h’8F
        19. 8.6.2.19 Marvell PXA Internal 2 Revision Register (II1RR) 8h’8F Definitions
        20. 8.6.2.20 Register Programming Examples
          1. 8.6.2.20.1 Example 1: Start-of-Day (SOD) Sequence
          2. 8.6.2.20.2 Example 2: Voltage Change Sequence
          3. 8.6.2.20.3 I2C Data Exchange Between Master and Slave Device
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 LDO Considerations
          1. 9.2.2.1.1 External Capacitors
          2. 9.2.2.1.2 Input Capacitor
          3. 9.2.2.1.3 Output Capacitor
          4. 9.2.2.1.4 No-Load Stability
          5. 9.2.2.1.5 Capacitor Characteristics
        2. 9.2.2.2 Buck Considerations
          1. 9.2.2.2.1 Inductor Selection
            1. 9.2.2.2.1.1 Method 1
            2. 9.2.2.2.1.2 Method 2
          2. 9.2.2.2.2 Input Capacitor Selection
          3. 9.2.2.2.3 Output Capacitor Selection
          4. 9.2.2.2.4 Buck Output Ripple Management
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Related Documentation
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7 Specifications

7.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)(2)
MIN MAX UNIT
All inputs −0.3 6.5 V
GND-to-GND SLUG −0.3 0.3 V
Junction temperature, TJ-MAX 150 °C
Power dissipation (TA = 70°C)(3) 3.2 W
Maximum lead temperature (soldering) 260 °C
Storage temperature, Tstg –65 150 °C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) If Military/Aerospace specified devices are required, contact the TI Sales Office/Distributors for availability and specifications.
(3) In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = 125°C), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package in the application (RθJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (RθJA × PD-MAX).

7.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V
Machine model ±200
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

7.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)
MIN NOM MAX UNIT
VIN 2.7 5.5 V
VINLDO4, 5 1.74 VIN V
Junction temperature, TJ −40 125 °C
Operating temperature, TA −40 85 °C
Maximum power dissipation (TA = 70°C)(3)(2)(1) 2.2 W
(1) In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = 125°C), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package in the application (RθJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (RθJA × PD-MAX).
(2) Junction-to-ambient thermal resistance (RθJA) is taken from a thermal modeling result, performed under the conditions and guidelines set forth in the JEDEC standard JESD51–7. The test board is a 4-layer FR-4 board measuring 102 mm × 76 mm × 1.6 mm with a 2 × 1 array of thermal vias. The ground plane on the board is 50 mm × 50 mm. Thickness of copper layers are 36 µm/1.8 µm/18 µm/36 µm (1.5 oz/1 oz/1 oz/1.5 oz). Ambient temperature in simulation is 22°C, still air. Power dissipation is 1W. Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power dissipation exists, special care must be paid to thermal dissipation issues in board design. The value of RθJA of this product can vary significantly, depending on PCB material, layout, and environmental conditions. In applications where high maximum power dissipation exists (high VIN, high IOUT), special care must be paid to thermal dissipation issues. For more information on these topics, see Texas Instruments Application Note Leadless Leadframe Package (LLP)(SNOA401).

7.4 Thermal Information

THERMAL METRIC(1) LP3972 UNIT
RSB (WQFN)
40 PINS
RθJA Junction-to-ambient thermal resistance 25 °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report (SPRA953).

7.5 Electrical Characteristics

Typical values and limits apply for TJ = 25°C; minimum and maximum limits apply over the entire junction temperature range for operation, −40°C to +125°C, unless otherwise specified. All voltages are with respect to the potential at the GND pin.(1)(2)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VIN, VDDA, VIN bucks 1, 2 and 3 Battery voltage 2.7 3.6 5.5 V
VINLDO4, VINLDO5 Power supply for LDOs 4 and 5 1.74 3.6 VIN V
TSD Thermal shutdown(3) Temperature 160 °C
Hysteresis 20
(1) All limits specified at room temperature and at temperature extremes. All room temperature limits are production tested, ensured through statistical analysis or ensured by design. All limits at temperature extremes are ensured via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
(2) Input supply must not be higher then VDDA.
(3) This electrical specification is ensured by design.

7.6 Electrical Characteristics: LDO RTC

VIN = 3.6 V, CIN = 1 µF, COUT = 0.47 µF, COUT (VRTC) = 1 µF ceramic (unless otherwise noted).
Typical values and limits apply for TJ = 25°C; minimum and maximum limits apply over the entire junction temperature range for operation, −40°C to +125°C, unless otherwise specified. All voltages are with respect to the potential at the GND pin.(1)(2)(3)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VOUT accuracy Output voltage accuracy VIN connected, load current = 1 mA 2.632 2.8 2.968 V
ΔVOUT Line regulation VIN = (VOUT(NOM) + 1 V) to 5.5 V(4)
Load current = 1 mA		 0.15 %/V
Load regulation From main battery
Load current = 1 mA to 30 mA		 0.05 %/mA
From backup battery, VIN = 3 V
Load current = 1 mA to 10 mA		 0.5
ISC Short-circuit current limit From main battery
VIN = VOUT + 0.3 V to 5.5 V		 100 mA
From backup battery 30
VIN – VOUT Dropout voltage Load current = 10 mA 375 mV
IQ_MAX Maximum quiescent current IOUT = 0 mA 30 µA
TP1 RTC LDO input switched from main battery to backup battery VIN falling 2.9 V
TP2 RTC LDO input switched from backup battery to main battery VIN rising 3 V
COUT Output capacitor Capacitance for stability 0.7 1 µF
ESR 5 500 mΩ
(1) All limits specified at room temperature and at temperature extremes. All room temperature limits are production tested, ensured through statistical analysis or ensured by design. All limits at temperature extremes are ensured via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
(2) Dropout voltage is the input-to-output voltage difference at which the output voltage is 100 mV below its nominal value.
(3) LDO_RTC voltage can track LDO3 voltage. LP3972 has a tracking function (nIO_TRACK). When enabled, LDO_RTC voltage tracks LDO3 voltage within 200 mV down to 2.8 V when LDO3 is enabled.
(4) VIN minimum for line regulation values is 2.7 V for LDOs 1–3 and 1.8 V for LDOs 4 and 5. Condition does not apply to input voltages below the minimum input operating voltage.

7.7 Electrical Characteristics: LDOs 1 to 5

VIN = 3.6 V, CIN = 1 µF, COUT = 0.47 µF, COUT (VRTC) = 1.0 µF ceramic (unless otherwise noted). Typical values and limits apply for TJ = 25°C; minimum and maximum limits apply over the entire junction temperature range for operation, −40°C to +125°C, unless otherwise specified. All voltages are with respect to the potential at the GND pin.(1)(2)(3)(4)(5)(6)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VOUT accuracy Output voltage accuracy (default VOUT) Load current = 1 mA –3% 3%
ΔVOUT Line regulation VIN = 3.1 V to 5 V(4),
Load Current = 1 mA		 0.15 %/V
Load regulation VIN = 3.6 V,
Load current = 1 mA to IMAX		 0.011 %/mA
ISC Short-circuit current limit LDO1–4, VOUT = 0 V 400 mA
LDO5, VOUT = 0 V 500
VIN – VOUT Dropout voltage Load current = 50 mA(2) 150 mV
PSRR Power Supply Ripple Rejection ƒ = 10 kHz, load current = IMAX 45 dB
IQ Quiescent current On IOUT = 0 mA 40 µA
Quiescent current On IOUT = IMAX 60
Quiescent current Off EN is de-asserted 0.03
TON Turnon time Start-up from shutdown 300 µs
COUT Output capacitor Capacitance for stability
0°C ≤ TJ ≤ 125°C		 0.33 0.47 µF
−40°C ≤ TJ ≤ 125°C 0.68 1.0
ESR 5 500 mΩ
(1) All limits specified at room temperature and are production tested, ensured through statistical analysis or ensured by design. All limits at temperature extremes are ensured via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
(2) Dropout voltage is the input-to-output voltage difference at which the output voltage is 100 mV below its nominal value.
(3) LDO_RTC voltage can track LDO3 voltage. LP3972 has a tracking function (nIO_TRACK). When enabled, LDO_RTC voltage tracks LDO3 voltage within 200 mV down to 2.8 V when LDO3 is enabled.
(4) VIN minimum for line regulation values is 2.7 V for LDOs 1–3 and 1.8 V for LDOs 4 and 5. Condition does not apply to input voltages below the minimum input operating voltage.
(5) An increase in the load current results in a slight decrease in the output voltage and vice versa.
(6) Dropout voltage is the input-to-output voltage difference at which the output voltage is 100 mV below its nominal value. This specification does not apply for input voltages below 2.7 V for LDOs 1 to 3 and 1.8 V for LDOs 4 and 5.

7.8 Electrical Characteristics: Buck Converters SW1, SW2, SW3

VIN = 3.6 V, CIN = 10 µF, COUT = 10 µF, LOUT = 2.2-µH ceramic (unless otherwise noted). Values and limits apply for TJ = 25°C. All voltages are with respect to the potential at the GND pin.(1)(2)(3)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VOUT Output voltage accuracy Default VOUT −3% 3%
Eff Efficiency Load current = 500 mA 95%
ISHDN Shutdown supply current EN is de-asserted 0.1 µA
Sync mode clock frequency Synchronized from 13-MHz system clock 10.4 13 15.6 MHz
ƒOSC Internal oscillator frequency 2 MHz
IPEAK Peak switching current limit 2.1 2.4 A
IQ Quiescent current On No-load PFM mode 21 µA
No-load PWM mode 20
RDSON (P) Pin-pin resistance PFET 240 mΩ
RDSON (N) Pin-pin resistance NFET 200 mΩ
TON Turnon time Start-up from shutdown 500 µs
CIN Input capacitor Capacitance for stability 8 µF
COUT Output capacitor Capacitance for stability 8 µF
(1) All limits specified at room temperature and at temperature extremes. All room temperature limits are production tested, ensured through statistical analysis or ensured by design. All limits at temperature extremes are ensured via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
(2) The input voltage range recommended for ideal applications performance for the specified output voltages is VIN = 2.7 V to 5.5 V for 0.8 V < VOUT < 1.7 VVIN = (VOUT + 1 V) to 5.5 V for 1.8 V ≤ VOUT ≤ 3.3 V.
(3) Test condition for VOUT < 2.7 V, VIN = 3.6 V; for VOUT ≥ to 2.7 V, VIN = VOUT + 1 V.

7.9 Electrical Characteristics: Backup Charger

VIN = VBATT = 3.6 V (unless otherwise noted). Typical values and limits apply for TJ = 25°C; minimum and maximum limits apply over the entire junction temperature range for operation, −40°C to +125°C. All voltages are with respect to the potential at the GND pin.(1)(2)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VIN Operational voltage range Voltage at VIN 3.3 5.5 V
IOUT Backup battery charging current VIN = 3.6 V, Backup_Bat = 2.5 V
backup battery charger enabled		 190 µA
VOUT Charger termination voltage VIN = 5 V, backup battery charger enabled; programmable 2.91 3.1 V
Backup battery charger short circuit current Backup_Bat = 0 V, backup battery charger enabled 9 mA
PSRR Power supply ripple rejection ratio IOUT ≤ 50 µA, VOUT = 3.15 V
VOUT + 0.4 ≤ VBATT = VIN ≤ 5 V
ƒ < 10 kHz		 15 dB
IQ Quiescent current IOUT < 50 µA 25 µA
COUT Output capacitance 0 µA ≤ IOUT ≤ 100 µA 0.1 µF
Output capacitor ESR 5 500 mΩ
(1) All limits specified at room temperature and at temperature extremes. All room temperature limits are production tested, ensured through statistical analysis or ensured by design. All limits at temperature extremes are ensured via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
(2) Backup battery charge current is programmable via the I2C-compatible interface.

7.10 Electrical Characteristics: I2C Compatible Serial Interface (SDA and SCL)

VIN = 3.6 V (unless otherwise noted). Typical values and limits appearing in normal type apply for TJ = 25°C; minimum and maximum limits apply over the entire junction temperature range for operation, −40°C to +125°C. All voltages are with respect to the potential at the GND pin.(1)(2)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VIL Low level input voltage See(3) −0.5 0.3 VRTC V
VIH High level input voltage See(3) 0.7 VRTC VRTC
VOL Low level output voltage See(3) 0 0.2 VTRC
IOL Low level output current VOL = 0.4 V(3) 3 mA
FCLK Clock frequency See(3) 400 kHz
(1) All limits specified at room temperature and are production tested, ensured through statistical analysis or ensured by design.
(2) The I2C signals behave like open-drain outputs and require an external pullup resistor on the system module in the 2-kΩ to 20-kΩ range.
(3) This electrical specification is ensured by design.

7.11 Logic Inputs and Outputs DC Operating Conditions

VIN = VBATT = 3.6 V (unless otherwise noted). Typical values and limits apply for TJ = 25°C; minimum and maximum limits apply over the entire junction temperature range for operation, −40°C to +125°C. All voltages are with respect to the potential at the GND pin.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
LOGIC INPUTS (SYS_EN, PWR_EN, SYNC, nRSTI, PWR_ON, nTEST_JIG, SPARE and GPIs)
VIL Low-level input voltage 0.5 V
VIH High-level input voltage VRTC − 0.5 V V
ILEAK Input leakage current −1 1 µA
LOGIC OUTPUTS (nRSTO, EXT_WAKEUP and GPOs)
VOL Output low level Load = 0.2 mA = IOL maximum 0.5 V
VOH Output high level Load = −0.1 mA = IOL maximum VRTC − 0.5 V V
ILEAK Output leakage current VON = VIN 5 µA
LOGIC OUTPUT (nBATT_FLT)
nBATT_FLT threshold voltage Programmable via serial interface
Default = 2.8 V		 2.4 2.8 3.4 V
VOL Output low level Load = 0.4 mA = IOL maximum 0.5 V
VOH Output high level Load = −0.2 mA = IOH maximum VRTC − 0.5 V V
ILEAK Input leakage current 5 µA

7.12 I2C Compatible Serial Interface Timing Requirements (SDA and SCL)

All voltages are with respect to the potential at the GND pin. See(1)(2)(3)
MIN NOM MAX UNIT
tBF Bus-free time between start and stop 1.3 µs
tHOLD Hold Time repeated start condition 0.6 µs
tCLKLP CLK low period 1.3 µs
tCLKHP CLK high period 0.6 µs
tSU Setup time repeated start condition 0.6 µs
tDATAHLD Data hold time 0 µs
tCLKSU Data set up time 100 ns
TSU Setup time for start condition 0.6 µs
TTRANS Maximum pulse width of spikes that must be suppressed by the input filter of both DATA and CLK signals 50 ns
(1) All limits specified at room temperature and are production tested, ensured through statistical analysis or ensured by design.
(2) The I2C signals behave like open-drain outputs and require an external pullup resistor on the system module in the 2-kΩ to 20-kΩ range.
(3) This electrical specification is ensured by design.

7.13 Power-On Timing Delays

See Initial Cold Start Power-On Sequence.
DESCRIPTION MIN TYP MAX UNIT
t1 Delay from VCC_RTC assertion to nRSTO de-assertion 50 ms
t2 Delay from nBATT_FLT de-assertion to nRSTI assertion 100 µs
t3 Delay from nRST de-assertion to SYS_EN assertion 10 ms
t4 Delay from SYS_EN assertion to PWR_EN assertion 125 ms
t5 Delay from PWR_EN assertion to nRSTO de-assertion 125 ms

7.14 Typical Characteristics

7.14.1 LDO Dropout Voltage vs Load Current Collect Data for all LDOs

LP3972 20207629.gif
Figure 1. Dropout Voltage vs Load Current
LP3972 20207631.gif
VIN = 3 V to 4 V VOUT = 1.8 V Load = 100 mA
Figure 3. LDO1 Line Regulation
LP3972 20207633.gif
SYS_ENABLE from 0 Load (V) = 100 mA LDO1 Channel 2 LDO4 Channel 1
Figure 5. Enable Start-Up Time (LDO1)
LP3972 20207630.gif
Figure 2. Change In Output Voltage vs Load Current
LP3972 20207632.gif
VIN = 4.1 V VOUT = 1.8 V No-Load = 100 mA
Figure 4. LDO1 Load Transient

7.14.2 Buck1 Output Efficiency vs. Load Current Varied From 1 mA to 1.5 A

LP3972 20207634.gif
VIN = 3 V, 3.5 V VOUT = 1.4 V
Figure 6. Buck1 Efficiency
LP3972 20207636.gif
VIN = 3 V, 3.5 V VOUT = 1.4 V
Figure 8. Buck1 Efficiency
LP3972 20207638.gif
VIN = 4.1 V VOUT = 1.4 V 980 mA [Channel 2]
Figure 10. Start-up into PWM Mode
LP3972 20207635.gif
VIN = 4 V to 4.5 V VOUT = 1.4 V
Figure 7. Buck1 Efficiency
LP3972 20207639.gif
VIN = 4.1 V VOUT = 1.4 V (PFM to PWM)
Figure 9. Mode Change Load Transients 20 mA To 560 mA