hcs201 Microchip Technology Inc., hcs201 Datasheet - Page 12

• Manufacturer Part Number: hcs201
• Description: Keeloq Code Hopping Encoder
• Manufacturer: Microchip Technology Inc.

HCS201
5.6
The integrated Step Up regulator can be used to
ensure the power supply voltage to the encoder and
the RF circuit (V
the battery voltage is (V
pared to V
falls below this voltage the STEP output is pulsed at
f
cuit as illustrated in Figure 5-2, to provide a step up
voltage on the device.
The Step Up regulator is inactive when the device is not
transmitting.
FIGURE 5-3:
TABLE 5-2:
DS41098C-page 12
STEP
Symbol
Note:
V
Note:
Note:
f
STEP
STEP
. This output can be connected to an external cir-
Step Up Regulator
8
7
6
5
4
3
2
1
0
STEP
These are typical values not tested in production.
Power to the Step up regulator is taken
from the V
a 3.5V minimum, V
low as 2.0V for the Step Up circuit to start
operating.
These parameters are characterized but not tested.
Output frequency
Reference voltage
0
, the internal reference voltage. If V
DD
STEP UP CIRCUIT CHARACTERISTICS
), is constant independent of what
Parameters
DDB
TYPICAL LOADING CURVES (FIGURE 5-2 CIRCUIT)
DDB
pin. While V
). Input on V
DDB
5
minimum can be as
DD
DD
is limited to
Load(mA)
pin is com-
Min.
125
5.5
10
DD
Typ.
200
6.5
FIGURE 5-2:
External components sample values:
R = 5.1 K
C = 1.0 uF
15
2.0-6.0V
Three button remote control with Step up regulator
Max.
250
7.5
S0
S1
S2
V
DDB
D = ZHCS400CT (40V 0.4A Zetex)
L = 390 uH
20
STEP
DATA
APPLICATION CIRCUIT
V
V
Units
kHz
DD
SS
V
2001 Microchip Technology Inc.
Tx out
R
V
Vddb=2V
Vddb=2.5V
Vddb=3V
Vddb=3.5V
DDB
Conditions
= 3V
Q = 2N3904
Q
L
D
C
V
DD