TMS37157 datasheet(13/47 Pages) TI

13 / 47 page

TMS37157

EEPROM

ROM

CRC

GEN.

CONTROL

UNIT

TRP

INTF.

VOLT.

REG.

Q CL

CLEAR

VCL

GND

CHARGE

REG.

RVCL

SW5

VBAT

BAT

CBAT

PUSH

BATBATI

VBATION

VBATI

CBATI

RVBATI

VCCD

BUSY

SPI_CLK

SOMI

SIMO

VBATI

CLKA/M

TMS37157

www.ti.com

SWRS083A – SEPTEMBER 2009 – REVISED NOVEMBER 2009

POWER MANAGEMENT

The Power Management block is responsible for the master control of all power supplies plus several additional

tasks, such as responding when a push button is pressed, generating reset signals and receiving LF transponder

commands.

A block diagram of the power management function is shown in Figure 3. Activation of a push signal is detected

by an ultra low-power detection circuit. While waiting for a high signal at PUSH, the only active component in

theTMS73157 is a flip-flop, whose output is set when PUSH is set high. When this happens, SW5 is closed and

the Control Unit is powered up and initialized. Also VBAT is switched to VBATI to power up a connected

microcontroller. The Microcontroller can, after performing its desired actions, send a Power Down Command to

the TMS37157, bringing the TMS37157 in the ultra low power mode (the Flip Flip is cleared and VBATI is

disconnected waiting for a PUSH High signal to appear.

When the Transponder Interface receives an MSP Access Command the Control Unit is powered up and

initialized and sets the VBATI ON signal, which switches on the uC. The Control Unit waits for

μC to fetch the

data, process it and send the processed data back to the Control Unit. The TMS37157 switches VBATI off and

waits for the RF to switch. If it detects a loss of the RF is transmitts the MSP Access data back .Then the

TMS37157 goes into the ultra low power sleep mode again. Throughout the whole MSP Access process the RF

of the reader has to stay on, because the TMS37157 Control Unit is powered out of the RF - field.

Figure 3. TMS37157 Power Management

Submit Documentation Feedback

Product Folder Link(s): TMS37157

TMS37157 Datasheet(PDF) 13 Page - Texas Instruments

TMS37157 Datasheet(HTML) 13 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

Datasheet Download

Link URL