LP3972 datasheet(41/59 Pages) TI1

41 / 59 page

PWR_ON

nTEST_JIG

SPARE

Internal Thermal Early Warning

10 ms

EXT_WAKEUP

PWR_ON

nTEST_JIG

SPARE

LP3972

www.ti.com

SNVS468J – SEPTEMBER 2006 – REVISED AUGUST 2011

Figure 28.

WAKEUP register bits

Reason for WAKEUP

WUP0

SPARE

WUP1

TEST_JIG

WUP2

PWR_ON short pulse

WUP3

PWR_ON long pulse

TSD_EW

TSD Early Warning

INTERNAL THERMAL SHUTDOWN PROCEDURE

Thermal shutdown is build to generate early warning (typ. 125°C) which triggers the EXT_WAKEUP for the

processor acknowledge. When a thermal shutdown triggers (typ. 160°C) the PMU will reset the system until the

device cools down.

BATTERY SWITCH AND BACK UP BATTERY CHARGER

When Back-Up battery is connected but the main battery has been removed or its supply voltage too low,

LP3972 uses Back-Up Battery for generating LDO_RTC voltage. When Main Battery is available the battery FET

switches over to the main battery for LDO_RTC voltage. When Main battery voltage is too low or removed

nBATT_FLT is asserted. If no back up battery exists, the battery switch to back up can be switched off by

nBU_BAT_EN bit. User can set the battery fault determination voltage and battery charger current via I2C

compatible interface. Enabling of back up battery charger can be done via serial interface (nBAT_CHG_EN) or

external charger enable pin (nCHG_EN). Pin 29 is set as external charger enable input by default.

GENERAL PURPOSE I/O FUNCTIONALITY (GPIO1 AND GPIO2)

LP3972 has 2 general purpose I/Os for system control. I2C compatible interface will be used for setting any of the

pins to input, output or hi-Z mode. Inputs value can be read via serial interface (GPIO1,2 bits). The pin 29

functionality needs to be set to GPIO by serial interface register bit nEXTCHGEN. (GPIO/CHG)

Controls

Port Function

Reg

batmonchg

GPIO<1>

Nextchgen_sel

bucen

GPIO1

Gpin 1

Function

Input = 0

Enabled

Input = 1

Not Enabled

Enabled

HiZ

Input (dig)->

Input

Output = 0

Submit Documentation Feedback

Product Folder Links: LP3972

LP3972 датащи(PDF) 41 Page - Texas Instruments

LP3972 датащи(HTML) 41 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59

датащи скачать

ссылки URL