L5993D STMicroelectronics, L5993D Datasheet - Page 9

• Manufacturer Part Number: L5993D
• Description: IC PWM CONTROLLER 16 SOIC
• Manufacturer: STMicroelectronics

Specifications of L5993D

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 1MHz
• Duty Cycle: 85%
• Voltage - Supply: 11 V ~ 20 V
• Buck: No
• Boost: No
• Flyback: Yes
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: Yes
• Operating Temperature: 0°C ~ 105°C
• Package / Case: 16-SOIC (3.9mm Width)
• Frequency-max: 1MHz
• Lead Free Status / RoHS Status: Contains lead / Request inventory verification
• Other names: 497-2387-5

Figure 21. Oscillator and synchronization internal schematic.
ered at pin 1 and defines the upper extreme of the
duty cycle range, D
and calculation).
In case V
switching frequency of the system will be a half
f
If the IC is to be synchronized to an external oscil-
lator, R
lower than the master frequency in any condition
(typically, 10-20% ), depending on the tolerance
of R
Pin 3. DC (Duty Cycle Control). By biasing this
pin with a voltage between 1 and 3 V it is possible
to set the maximum duty cycle between 0 and the
upper extreme D
If D
voltage V3 to be applied to pin 3 is:
D
tween V3 and the oscillator ramp (see fig. 22),
thus in case the device is synchronized to an ex-
ternal frequency f
amplitude is reduced), (4) changes into:
A voltage below 1V will inhibit the driver output
stage. This could be used for a not-latched device
disable, for example in case of overvoltage pro-
tection (see application ideas).
If no limitation on the maximum duty cycle is re-
osc
max
.
max
T
R
C
T
T
and C
is determined by internal comparison be-
V
T
3
is the desired maximum duty cycle, the
V
RCT
15
and C
REF
5
T
is connecte d to VREF, however, the
.
V
4 exp
4
2
3
T
x
= 5 - 2
ext
(see pin 15).
should be selected for a f
x
50
(and therefore the oscillator
D1
(see pin 15 for D
CLAMP
(2-Dmax)
R
T
D
R3
C
max
T
(4)
f
ext
R1
R2
x
(5)
definition
+
-
osc
Figure 22. Duty cycle control.
quired (i.e. D
ing. An internal pull-up (see fig. 22) holds the volt-
age above 3V. Should the pin pick up noise (e.g.
during ESD tests), it can be connected to VREF
through a 4.7k resistor.
Pin 4. VREF (Reference Voltage). The device is
provided with an accurate voltage reference
(5V 1.5%) able to deliver some mA to an external
circuit.
A small film capacitor (0.1 F typ.), connected
between this pin and SGND, is recommended to
ensure the stability of the generator and to prevent
noise from affectingthe reference.
Before device turn-on, this pin has a sink current
capability of 0.5mA.
R
C
T
T
R1
R2
MAX
V
RCT
= D
REF
DC
X
SYNC
), the pin has to be left float-
600 A
D97IN500B
4
3
2
1
+
-
3 A
D97IN711A
TO PWM LOGIC
D
R
CLK
23K
28K
Q
L5993
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