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Спецификация NTE1721 изготовлена «NTE» и имеет функцию, называемую «Integrated Circuit Pulse Width Modulator (PWM) Regulator». |
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Детали детали
Номер произв | NTE1721 |
Описание | Integrated Circuit Pulse Width Modulator (PWM) Regulator |
Производители | NTE |
логотип |
4 Pages
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NTE1721 & NTE1723
Integrated Circuit
Pulse Width Modulator (PWM) Regulator
Description:
The NTE1721 and NTE1723 are pulse width modulator control–circuits designed to offer improved
performance and lowered external parts count when implemented for controlling all types of switching
power supplies. The no–chip +5.1V reference is trimmed to ±1% and the input common–mode range
of the errror amplifier includes the reference voltage, thus eliminating the need for external divider
resistors. A sync input to the oscillator enables multiple units to be slaved or a single unit to be syn-
chronized to an external system clock. A wide range of dead time can be programmed by a single
resistor connected between the CT and the Discharge pins. These devices also feature a built–in
soft–start circuitry, requiring only an external timing capacitor. A shutdown pin controls both the soft–
start circuitry and the output stages, provided instantaneous turn–off through the PWM latch with
pulsed shutdown, as well as soft–start recycle with longer shutdown commands. The under voltage
lockout inhibits the outputs and the changing of the soft–start capacitor when VCC is below nominal.
The output stages are totem–pole design capable of sinking and sourcing in excess of 200mA. The
output stages of the NTE1721 features NOR logic resulting in a low output for an off state while the
NTE1723 utilizes OR logic which gives a high output when off.
Features:
D 8V to 35V Operation
D +5.1V ±1% Trimmed Reference
D 100Hz to 400kHz Oscillator Range
D Separate Oscillator Sync Pin
D Adjustable Dead Time Control
D Input Undervoltage Lockout
D Latching PWM to Prevent Multiple Pulses
D Pulse–by–Pulse Shutdown
D Dual Source/Sink Outputs: ±400mA Peak
Absolute Maximum Ratings: (Note 1)
Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +40V
Collector Supply Voltage, VC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +40V
Logic Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to +5.5V
Analog Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to VCC
Output Current, Source or Sink, IO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±500mA
Reference Output Current, Iref . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50mA
Oscillator Charging Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5mA
Power Dissipation (TA = +25°C), PD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000mW
Derate Above 50°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10mW/°C
Power Dissipation (TC = +25°C), PD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2000mW
Derate Above 25°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16mW/°C
Operating Junction Temperature, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +150°C
Storage Temperature Range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –55° to +125°C
Thermal Resistance, Junction–to–Ambient, RthJA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100°C/W
Thermal Resistance, Junction–to–Case, RthJC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60°C/W
Lead Temperature (During Soldering, 10sec), TL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +300°C
Note 1 Values beyond which damage may occur
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Recommended Operating Conditions:
Parameter
Supply Voltage
Collector Supply Voltage
Output Sink/Source Current
Steady State
Peak
Reference Load Current
Oscillator Frequency Range
Oscillator Timing Resistor
Oscillator Timing Capacitor
Deadtime Resistor Range
Operating Ambient Temperature Range
Symbol Min Typ Max Unit
VCC 8.0 – 35.0 V
VC 4.5 – 35.0 V
IO
0 – ±100 mA
0 – ±400 mA
Iref 0 – 20 mA
fosc 0.1 – 400 kHz
RT 2.0 – 150 kΩ
CT 0.001 – 0.2 µF
RD 0.5 – – Ω
TA 0 – 70 °C
Electrical Characteristics: (VCC = +20V, TA = 0° to +70°C unless otherwise specified)
Parameter
Symbol
Test Conditions
Min Typ Max Unit
Reference Section
Reference Output Voltage
Line Regulation
Load Regulation
Temperature Stability
Total Output Variation (Includes Line
and Load Regulation over
Temperature
Vref
Regline
Regload
∆Vref/∆T
∆Vref
TJ = +25°C
+8V ≤ VCC ≤ +35V
0mA ≤ IL ≤ 20mA
5.0 5.1 5.2
– 10 20
– 20 50
– 20 –
4.95 – 5.25
V
mV
mV
mV
V
Short Circuit Current
ISC Vref = 0V, TJ = +25°C
– 80 100 mA
Output Noise Voltage
Vn 10Hz ≤ f ≤ 10kHz, TJ = +25°C
– 40 200 µVrms
Long Term Stability
S TJ = +25°C, Note 2
– 20 50 mV/kHr
Oscillator Section (Tested at fosc = 40kHz, RT = 3.6kΩ, CT = 0.001µF, RD = 0Ω unless otherwise specified)
Initial Accuracy
TJ = +25°C
– ±2 ±6 %
Frequency Stability with Voltage
fosc/VCC +8V ≤ VCC ≤ +35V
– ±1 ±2 %
Frequency Stability with Temperature fosc/T
– ±3 –
%
Minimum Frequency
fmin RT = 150kΩ, CT = 0.2µF
– 50 –
Hz
Maximum Frequency
fmax RT = 2kΩ, CT = 1.0nF
400 – – kHz
Current Mirror
IRT = 2mA
1.7 2.0 2.2 mA
Clock Amplitude
3.0 3.5 –
V
Clock Width
TJ = +25°C
0.3 0.5 1.0 µs
Sync Threshold
1.2 2.0 2.8
V
Sync Input Current
Sync Voltage = +3.5V
– 1.0 2.5 mA
Error Amplifier Section (VCM = +5.1V)
Input Offset Voltage
Input Bias Current
VIO
IIB
– 2.0 10.0 mV
– 1.0 10.0 µA
Note 2. Since long term stability cannot be measured on each device before shipment, this specifica-
tion is an engineering estimate of average stability from lot to lot.
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Electrical Characteristics (Cont’d): (VCC = +20V, TA = 0° to +70°C unless otherwise specified)
Parameter
Symbol
Test Conditions
Min Typ Max Unit
Error Amplifier Section (Cont’d) (VCM = +5.1V)
DC Open Loop Gain
AVOL
Low Level Output Voltage
VOL
High Level Output Voltage
VOH
Common Mode Rejection Ratio
CMRR
Power Supply Rejection Ratio
PSRR
PWM Comparator Section
RL ≤ 10MΩ
+1.5V≤ VCM ≤ +5.2V
+8V ≤ VCC ≤ +35V
60 75 –
– 0.2 0.5
3.8 5.6 –
60 75 –
50 60 –
dB
V
V
dB
dB
Minimum Duty Cycle
Maximum Duty Cycle
Input Threshold, Zero Duty Cycle
Input Threshold, Maximum Duty Cycle
DCmin
DCmax
VTH
fosc = 40kHz, RT = 3.6kΩ,
CT = 0.01µF, RD = 0Ω
––0
45 49 –
0.6 0.9 –
– 3.3 3.6
%
%
V
V
Input Bias Current
Soft–Start Section
IIB
– 0.05 1.0 µA
Soft–Start Current
Soft–Start Voltage
Shutdown Input Current
Output Drivers (Each Output, VCC = +20V)
Output Low Level
VOL
Output High Level
VOH
Under Voltage Lockout
Collector Leakage
Rise Time
Fall Time
Shutdown Delay
Supply Current
VUL
IC(leak)
tr
tf
tds
ICC
Vshutdown = 0V
Vshutdown = 2.0V
Vshutdown = 2.5V
Isink = 20mA
Isink = 100mA
Isink = 20mA
Isink = 100mA
V8 and V9 = High
VC = +35V, Note 3
CL = 1.0nF, TJ = +25°C
CL = 1.0nF, TJ = +25°C
VDS = +3V, CS = 0, TJ = +25°C
VCC = +35V
25 50 80
– 0.4 0.6
– 0.4 1.0
µA
V
mA
– 0.2 0.4
– 1.0 2.0
18 19 –
17 18 –
6.0 7.0 8.0
– – 200
– 100 600
– 50 300
– 0.2 0.5
– 14 20
V
V
V
V
V
µA
ns
ns
µs
mA
Note 3.Applies to NTE1721 Only, due to polarity of output pulses.
Application Information (Shutdown Options):
Since both the compensation and soft–start terminals (Pin9 and Pin8) have current source pull–ups,
either can readily accept a pull–down signal which only has to sink a maximum of 100µA to turn off
the outputs. This is subject to the added requirement of discharging whatever external capacitance
may be attached to these pins.
An alternate approach is the use of the shutdown circuitry of Pin10 which has been improved to en-
hance the available shutdown options. Activating this circuit by applying a positive signal on Pin10
performs two functions: the PWM latch is immediately set providing the fastest turn–off signal to the
outputs; and a 150µA current sink begins to discharge the external soft–start capacitor. If the shut-
down command is short, the PWM signal is terminated without significant discharge of the soft–start
capacitor, thus, allowing, for example, a convenient implementation of pulse–by–pulse current limit-
ing. Holding Pin10 high for a longer duration, however, will ultimately discharge this external capaci-
tor, recycling slow turn–on upon release.
Pin10 should not be left floating as noise pickup could conceivably interrupt normal operation.
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