U2270B Datasheet, PDF (4/13 Pages) TEMIC Semiconductors – Read / Write Base Station IC

U2270B
The following section explains the 3 different
operation modes to power the U2270B.
1. One-rail operation
All internal circuits are operated from one 5-V power rail.
(see figure 5). In this case, V_S ,V_EXT and DV_S serve as
inputs. V_Batt is not used but should also be connected to
that supply rail.
+5 V (stabilized)
D_VS V_EXT V_S V_Batt Standby
12579
Figure 5.
2. Two-rail operation
In that application, the driver voltage, DV_S, and the
pre-driver supply, V_EXT, are operated at a higher voltage
than the rest of the circuitry to obtain a higher
driver-output swing and thus a higher magnetic field,
refer to figure 6. V_S is connected to a 5-V supply, whereas
the driver voltages can be as high as 8 V. This operation
mode is intended to be used in situations where an
extended communication distance is required.
7 to 8 V (stabilized)
5 V (stabilized)
3. Battery-voltage operation
Using this operation mode, V_S and V_EXT are generated by
the internal power supply. (refer to figure 7). For this
mode, an external voltage regulator is not needed. The IC
can be switched off via the pin Standby. V_EXT supplies the
base of an external NPN transistor and external circuits,
i.e., a microcontroller (even in Standby mode).
Pin V_EXT and V_Batt are overvoltage protected via internal
Zener diodes (refer figure 4).The maximum current into
that pins is determined by the maximum power dissipa-
tion and the maximum junction temperature of the IC. For
a short-time current pulse, a higher power dissipation can
be assumed (refer to application note ANT019).
7 to 16 V
D_VS V_EXT V_S V_Batt Standby
Figure 7.
12600
D_VS V_EXT V_S V_Batt Standby
12580
Figure 6.
Table 1. The following table summarizes the characteristics of the various operation modes.
Operation Mode
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _{1. One-rail operation}
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _{2. Two-rail operation}
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ^{3. Battery voltage}
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ^operation
External Components Re-
quired
1 Voltage regulator
1 Capacitor
2 Voltage regulators
2 Capacitors
1 Transistor
2 Capacitors
Optional for load-dump
protection:
1 Resistor
1 Capacitor
Supply Voltage Range
5 V ± 10%
5 V ± 10%
7 V to 8 V
6 V to 16 V
Driver Output
[ Voltage Swing
4V
6 V to 7 V
[4V
Standby Mode
Available
No
No
Yes
4 (13)
TELEFUNKEN Semiconductors
Rev. A3, 13-Dec-96