Consumer Appliances such as Blenders, Range Hoods, Fans, etc.
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Lamp Dimmer for control of high-voltage lamps and electronic-transformer
coupled low-voltage lamps such as Halogen Lamps.
DESCRIPTION:
The LS7317 is a MOS circuit for controlling the speed of an AC motor.
Five inputs, PL1/ through PL5/ are provided to select five speed/power
levels between 40% and 96% of full power. A BOOST/ input is provided to
override any selected power level with a jump to 99% of full power.
A PULSE/ input provides for periodic two seconds on, two seconds off
auto-pulse cycle for one minute. All these inputs require momentary ac-
tivation which can very conveniently be produced by push-button dome or
leaf switches. When a logic low is applied through such a push-button
switch to any of the speed inputs or the Pulse input, the input becomes
active and switches state to become an output for driving an external LED
and display the selected speed level. A TRIG/ output is also turned on to
drive the trigger input of a triac in series with the motor and control its
speed by controlling the firing angle of the triac. Phase synchronization of
the external AC and the triac trigger is made with an internal PLL, with the
AC signal being applied to the SYNC input of the LS7317. An OFF/ input
is provided for turning the motor off with a momentary push-button switch.
The LS7317 can also be used as a Lamp Dimmer providing 5 selectable
intensity levels as indicated in the application schematic shown in Figure
5. The
LOAD
can be either a high voltage lamp or the input to an
electronic-transformer coupling to a low-voltage lamp. In the Lamp Dim-
mer application, the Pulse/ and Boost/ inputs are not used
INPUTS/OUTPUTS
PL1/ - PL5/
(Pin 1 - Pin 5)
Five inputs/outputs for selecting five speed/power levels. When no power
level is selected, such as upon a system power-up, PL1/ - PL5/ all act as
inputs. When a power level is selected by applying a logic low at one of
these inputs for the duration of TH (see Transient Characteristics section),
the output TRIG/ is turned on at the selected phase angle and the PL/ in-
put switches state to become a current-sinking output in order to drive a
display, such as an LED. It switches back to the input state when another
PL/ input or the OFF/ input is activated.
Power levels and triac conduction angles referenced to the SYNC input
(Pin 10) for each PL/ and Boost/ are shown in Table 1.
TABLE 1
PL2/
PL3/
PL4/
55%
69%
82%
95
掳
108
掳
122
掳
CONNECTION DIAGRAM - TOP VIEW
PL1/
PL2/
PL3/
PL4/
PL5/
PULSE/
BOOST/
14
13
12
11
10
9
8
NC
V
DD
(+V)
LSI
LS7317
FIGURE 1
1
2
3
4
5
6
7
TRIG/
V
SS
( - V )
SYNC
OFF/
CAP
PULSE/
(Pin 6)
A logic low applied to the PULSE/ input initiates the auto-pulse
cycle and causes the PULSE/ input to switch from an input to
an output state. Subsequently, when a speed level is selected,
the TRIG/ output is turned on for two seconds, then turned off
for two seconds. The two second on, two second off cycle is
repeated for one minute. At the end of one minute the auto-
pulse cycle is terminated with the TRIG/ output off and the
PULSE/ pin reverting back to the input state.
BOOST/
(Pin 7)
A logic low applied to the BOOST/ input causes the TRIG/ out-
put to be turned on at the maximum conduction angle, cor-
responding to 99% of full power. The boost state overrides any
prevalent state and continues as long as the BOOST/ input is
held at logic low. Upon returning BOOST/ to logic high, the cir-
cuit returns to and continues in the pre-Boost state.
OFF/
(Pin 9)
A logic low applied to the OFF/ input turns the TRIG/ output off,
aborts any auto-pulse cycle in progress and causes any active
PL/ pin or the PULSE/ pin to switch from the output to the input
state.
CAP
(Pin 8)
Input for the PLL external filter capacitor connection.
SYNC
(Pin 10)
Input for the PLL 50Hz/60Hz AC reference signal.
All internal timings are synchronized with the SYNC input.
TRIG/
(Pin 12)
The TRIG/ output is designed to drive the gate of a triac con-
nected in series with the load. When on, the TRIG/ output pro-
duces a 1.2ms/1ms wide negative pulse in each half-cycle of
the 50Hz/60Hz AC at a predefined phase angle which cor-
responds to the selected speed level. When off, TRIG/ sits at
logic high.
PL1/
% of Full Power:
40%
Conduction Angle
81
掳
PL5/ BOOST/
96%
99%
147
掳
160
掳
7317-112405-1
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