Texas Instruments TRF7970A Manual page 20
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TRF7970A
SLOS743L – AUGUST 2011 – REVISED MARCH 2017
6.3.3 Power Modes
The chip has several power states, which are controlled by two input pins (EN and EN2) and several bits
in the chip status control register (0x00) (see
MODE
EN2
Power down
0
Sleep mode
1
Standby mode at +3.3 VDC
X
Mode 1 at +3.3 VDC
X
Mode 2 at +3.3 VDC
X
Mode 3 (half power) at
X
+3.3 VDC
Mode 4 (full power) at
X
+3.3 VDC
(1) X = Don't care
MODE
EN2
Power down
0
Sleep mode
1
Standby mode at +5 VDC
X
Mode 1 at +5 VDC
X
Mode 2 at +5 VDC
X
Mode 3 (half power) at
X
+5 VDC
Mode 4 (full power) at
X
+5 VDC
(1) X = Don't care
Table 6-3
and
Table 6-4
system supply, respectively. The main reader enable signal is pin EN. When EN is set high, all of the
reader regulators are enabled, the 13.56-MHz oscillator is running and the SYS_CLK (output clock for
external microcontroller) is also available.
The input pin EN2 has two functions:
•
A direct connection from EN2 to V
auxiliary clock signal (60 kHz, SYS_CLK) for an external MCU. This mode (EN = 0, EN2 = 1) is
intended for systems in which the MCU is also being supplied by the reader supply regulator (V
and the MCU clock is supplied by the SYS_CLK output of the reader. This allows the MCU supply and
clock to be available during sleep mode.
•
EN2 enables the start-up of the reader system from complete power down (EN = 0, EN2 = 0). In this
case the EN input is being controlled by the MCU (or other system device) that is without supply
voltage during complete power down (thus unable to control the EN input). A rising edge applied to the
EN2 input (which has an approximately 1-V threshold level) starts the reader supply system and 13.56-
MHz oscillator (identical to condition EN = 1).
When user MCU is controlling EN and EN2, a delay of 1 ms between EN and EN2 must be used. If the
MCU controls only EN, TI recommends connecting EN2 to either V
application MCU requirements for V
20
Detailed Description
Table 6-3
Table 6-3. 3.3-V Operation Power Modes
CHIP
REGULATOR
STATUS
CONTROL
EN
CONTROL
TRANSMITTER
REGISTER
REGISTER
(0x0B)
(0x00)
0
XX
XX
0
XX
XX
1
80
00
1
00
00
1
02
00
1
30
07
1
20
07
Table 6-4. 5-V Operation Power Modes
CHIP
REGULATOR
STATUS
CONTROL
EN
CONTROL
TRANSMITTER
REGISTER
REGISTER
(0x0B)
(0x00)
0
XX
XX
0
XX
XX
1
81
07
1
01
07
1
03
07
1
31
07
1
21
07
show the configuration for the different power modes when using a 3.3-V or 5-V
to ensure the availability of the regulated supply V
IN
and SYS_CLK.
DD_X
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and
Table
6-4).
(1)
SYS_CLK
RECEIVER
(13.56 MHz)
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF
OFF
ON
OFF
ON
ON
ON
ON
ON
ON
ON
ON
(1)
SYS_CLK
RECEIVER
(13.56 MHz)
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF
OFF
ON
OFF
ON
ON
ON
ON
ON
ON
ON
ON
Copyright © 2011–2017, Texas Instruments Incorporated
TRF7970A
www.ti.com
TYPICAL
SYS_CLK
V
CURRENT
DD_X
(60 kHz)
(mA)
OUT (dBm)
OFF
OFF
<0.001
ON
ON
0.120
X
ON
2
X
ON
3
X
ON
9
X
ON
53
X
ON
67
TYPICAL
SYS_CLK
V
CURRENT
DD_X
(60 kHz)
(mA)
OUT (dBm)
OFF
OFF
<0.001
ON
ON
0.120
X
ON
3
X
ON
5
X
ON
10.5
X
ON
70
X
ON
130
DD_X
or GND, depending on the
IN
TYPICAL
POWER
-
-
-
-
-
14.5
17
TYPICAL
POWER
-
-
-
-
-
20
23
and an
)
DD_X
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