参数资料
型号: EM4095HMSO16A
元件分类: 线性稳压
英文描述: Single 12V Input Supply Dual Regulator - Synchronous Rectified Buck PWM and Linear Power Controller; Temperature Range: 0&degC to 70°C; Package: 14-SOIC
中文描述: 电信提供商/数据通信
文件页数: 8/10页
文件大小: 204K
代理商: EM4095HMSO16A
EM4095
Copyright
2002, EM Microelectronic-Marin SA
7
www.emmicroelectronic.com
Signal RDY/CLK
This signal provides the external microprocessor with
clock signal which is synchronous with the signal on ANT1
and with information about EM4095 internal state. Clock
signal synchronous with ANT1 indicates that PLL is in lock
and that Reception chain operation point is set. When
SHD is high RDY/CLK pin is forced low. After high to low
transition on SHD the PLL starts-up, and the reception
chain is switched on. After time TSET the PLL is locked and
reception chain operation point has been established. At
this moment the same signal which is being transmitted to
ANT1 is also put to RDY/CLK pin indicating to
microprocessor that it can start observing signal on
DEMOD_OUT and giving at the same time reference
clock signal. Clock on RDY/CLK pin is continuous, it is
also present during time the ANT drivers are OFF due to
high level on MOD pin. During the time TSET from high to
low transition on SHD pin RDY/CLK pin is pulled down by
100 k
pull down resistor. The reason for this is in
additional functionality of RDY/CLK pin in case of AM
modulation with index which is lower then 100%. In that
case it is used as auxiliary driver which maintains lower
amplitude on coil during modulation. (see also Typical
Operating Configuration)
Remark: Please refer to AN4095 for external components
calculation and limits.
Typical Operating Configuration
Read Only Mode
P
+5V
L
A
C
DV1
C
DV2
C
RES
P4095
2
3
4
5
6
7
8
1
15
14
13
12
11
10
9
16
+5V
RDY/CLK
C
DEC
C
AGND
MOD
DEMOD_OUT
SHD
C
DC2
C
FCAP
Fig. 6
Read/Write mode (Low Q factor antenna)
P
+5V
L
A
C
DV1
C
DV2
C
RES
C
DEC
C
AGND
P4095
2
3
4
5
6
7
8
1
15
14
13
12
11
10
9
16
+5V
MOD
DEMOD_OUT
SHD
C
DC2
C
FCAP
RDY/CLK
Fig. 7
Read/Write mode (High Q factor antenna)
P
+5V
L
A
C
DV1
C
DV2
C
RES
P4095
2
3
4
5
6
7
8
1
15
14
13
12
11
10
9
16
+5V
RDY/CLK
R
SER
C
DEC
C
AGND
MOD
DEMOD_OUT
SHD
C
DC2
C
FCAP
Fig. 8
Read/Write mode (AM modulation)
P
+5V
L
A
C
DV1
C
DV2
C
RES
P4095
2
3
4
5
6
7
8
1
15
14
13
12
11
10
9
16
+5V
RDY/CLK
R
AM
C
DEC
C
AGND
MOD
DEMOD_OUT
SHD
C
DC2
C
FCAP
Fig. 9
Figure 6 presents EM4095 used in Read Only mode. Pin
MOD is not used. It is recommended to connect it to VSS.
Figure 7 presents typical R/W configuration for OOK
communication protocol reader to transponder (eg.
EM4150). It is recommended to be used with low Q factor
antennas (up to 15).
When the antenna quality is high using configuration of
figure 6 or 7 the voltage on antenna can arrive in the
range of few hundred volts and antenna peak current may
exceed its maximum value. In such a case the capacitive
divider ratio has to be high thus limiting the sensitivity. For
such case it is better to reduce antenna circuit quality by
adding serial resistor. In this way the antenna current is
lower and thus power dissipation of IC is reduced with
practically the same performance (Fig. 8).
In the case AM modulation communication protocol
reader to transponder (eg. EM4069) is needed a single
ended configuration has to be used (figure 9). When pin
MOD is pulled high driver on ANT1 is put in three state,
driver RDY/CLK continues driving thus maintaining lower
antenna current. Modulation index is adjusted by resitor
RAM. As mentioned above RDY/CLK signal becomes
active only after the demodulation chain operating point is
set.
Before it is pulled down by high impedance pull down
resistor (100 k
) in order not to load ANT1 output. In the
case of AM modulation configuration the total antenna
current change at the moment RDY/CLK pin becomes
active, so external microprocessor has to wait another
TSET before it can start observing DEMOD_OUT.
EM4095
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