SWITCHMODE Pulse Width
Modulation Control Circuit
The TL494 is a fixed frequency, pulse width modulation control circuit designed primarily for SWITCHMODE power supply control.
•Complete Pulse Width Modulation Control Circuitry
•On±Chip Oscillator with Master or Slave Operation
•On±Chip Error Amplifiers
•On±Chip 5.0 V Reference
•Adjustable Deadtime Control
•Uncommitted Output Transistors Rated to 500 mA Source or Sink
•Output Control for Push±Pull or Single±Ended Operation
•Undervoltage Lockout
Order this document by TL494/D
TL494
SWITCHMODE
PULSE WIDTH MODULATION
CONTROL CIRCUIT
SEMICONDUCTOR
TECHNICAL DATA
D SUFFIX
PLASTIC PACKAGE
CASE 751B
(SO±16)
N SUFFIX
PLASTIC PACKAGE
CASE 648
MAXIMUM RATINGS (Full operating ambient temperature range applies, unless otherwise noted.)
Rating |
Symbol |
TL494C |
TL494I |
Unit |
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Power Supply Voltage |
VCC |
42 |
V |
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Collector Output Voltage |
VC1, |
42 |
V |
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VC2 |
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Collector Output Current |
IC1, IC2 |
500 |
mA |
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(Each transistor) (Note 1) |
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Amplifier Input Voltage Range |
VIR |
±0.3 to +42 |
V |
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Power Dissipation @ TA ≤ 45°C |
PD |
1000 |
mW |
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Thermal Resistance, |
RθJA |
80 |
°C/W |
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Junction±to±Ambient |
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Operating Junction Temperature |
TJ |
125 |
°C |
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Storage Temperature Range |
Tstg |
±55 to +125 |
°C |
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Operating Ambient Temperature Range |
TA |
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°C |
TL494C |
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0 to +70 |
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TL494I |
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± 25 to +85 |
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Derating Ambient Temperature |
TA |
45 |
°C |
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NOTE: 1. Maximum thermal limits must be observed.
PIN CONNECTIONS
Noninv |
1 |
+ |
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+ |
16 |
Noninv |
Input |
1 |
2 |
Input |
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Inv |
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Error |
Error |
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Inv |
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Amp |
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Amp |
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Input |
2 |
± |
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VCC |
± |
15 |
Input |
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Compen/PWN |
3 |
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5.0 V |
14 |
V |
Comp Input |
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≈ 0.1 V |
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REF |
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ref |
Deadtime |
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Output |
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4 |
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13 |
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Control |
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Control |
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CT |
5 |
Oscillator |
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12 |
VCC |
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RT |
6 |
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Q2 |
11 |
C2 |
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Ground |
7 |
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10 |
E2 |
C1 |
8 |
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Q1 |
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9 |
E1 |
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(Top View)
ORDERING INFORMATION
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Operating |
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Device |
Temperature Range |
Package |
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TL494CD |
TA = 0° to +70°C |
SO±16 |
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TL494CN |
Plastic |
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TL494IN |
TA = ± 25° to +85°C |
Plastic |
Motorola, Inc. 1996 |
Rev 1 |
TL494
RECOMMENDED OPERATING CONDITIONS
Characteristics |
Symbol |
Min |
Typ |
Max |
Unit |
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Power Supply Voltage |
VCC |
7.0 |
15 |
40 |
V |
Collector Output Voltage |
VC1, VC2 |
± |
30 |
40 |
V |
Collector Output Current (Each transistor) |
IC1, IC2 |
± |
± |
200 |
mA |
Amplified Input Voltage |
Vin |
±0.3 |
± |
VCC ± 2.0 |
V |
Current Into Feedback Terminal |
lfb |
± |
± |
0.3 |
mA |
Reference Output Current |
lref |
± |
± |
10 |
mA |
Timing Resistor |
RT |
1.8 |
30 |
500 |
kΩ |
Timing Capacitor |
CT |
0.0047 |
0.001 |
10 |
μF |
Oscillator Frequency |
fosc |
1.0 |
40 |
200 |
kHz |
ELECTRICAL CHARACTERISTICS (VCC = 15 V, CT = 0.01 μF, RT = 12 kΩ, unless otherwise noted.)
For typical values TA = 25°C, for min/max values TA is the operating ambient temperature range that applies, unless otherwise noted.
Characteristics |
Symbol |
Min |
Typ |
Max |
Unit |
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REFERENCE SECTION |
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Reference Voltage (IO = 1.0 mA) |
Vref |
4.75 |
5.0 |
5.25 |
V |
Line Regulation (VCC = 7.0 V to 40 V) |
Regline |
± |
2.0 |
25 |
mV |
Load Regulation (IO = 1.0 mA to 10 mA) |
Regload |
± |
3.0 |
15 |
mV |
Short Circuit Output Current (Vref = 0 V) |
ISC |
15 |
35 |
75 |
mA |
OUTPUT SECTION |
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Collector Off±State Current |
IC(off) |
± |
2.0 |
100 |
μA |
(VCC = 40 V, VCE = 40 V) |
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Emitter Off±State Current |
IE(off) |
± |
± |
±100 |
μA |
VCC = 40 V, VC = 40 V, VE = 0 V) |
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Collector±Emitter Saturation Voltage (Note 2) |
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V |
Common±Emitter (VE = 0 V, IC = 200 mA) |
Vsat(C) |
± |
1.1 |
1.3 |
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Emitter±Follower (VC = 15 V, IE = ±200 mA) |
Vsat(E) |
± |
1.5 |
2.5 |
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Output Control Pin Current |
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Low State (VOC ≤ 0.4 V) |
IOCL |
± |
10 |
± |
μA |
High State (VOC = Vref) |
IOCH |
± |
0.2 |
3.5 |
mA |
Output Voltage Rise Time |
tr |
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ns |
Common±Emitter (See Figure 12) |
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± |
100 |
200 |
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Emitter±Follower (See Figure 13) |
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± |
100 |
200 |
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Output Voltage Fall Time |
tf |
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ns |
Common±Emitter (See Figure 12) |
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± |
25 |
100 |
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Emitter±Follower (See Figure 13) |
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± |
40 |
100 |
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NOTE: 2. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient temperature as possible.
2 |
MOTOROLA ANALOG IC DEVICE DATA |
TL494
ELECTRICAL CHARACTERISTICS (VCC = 15 V, CT = 0.01 μF, RT = 12 kΩ, unless otherwise noted.)
For typical values TA = 25°C, for min/max values TA is the operating ambient temperature range that applies, unless otherwise noted.
Characteristics |
Symbol |
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Min |
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Typ |
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Max |
Unit |
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ERROR AMPLIFIER SECTION |
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Input Offset Voltage (VO (Pin 3) = 2.5 V) |
VIO |
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± |
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2.0 |
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10 |
mV |
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Input Offset Current (VO (Pin 3) = 2.5 V) |
IIO |
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± |
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5.0 |
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250 |
nA |
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Input Bias Current (VO (Pin 3) = 2.5 V) |
IIB |
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± |
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±0.1 |
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±1.0 |
μA |
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Input Common Mode Voltage Range (VCC = 40 V, TA = 25°C) |
VICR |
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±0.3 to VCC±2.0 |
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V |
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Open Loop Voltage Gain ( VO = 3.0 V, VO = 0.5 V to 3.5 V, RL = 2.0 kΩ) |
AVOL |
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70 |
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95 |
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± |
dB |
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Unity±Gain Crossover Frequency (VO = 0.5 V to 3.5 V, RL = 2.0 kΩ) |
fC± |
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± |
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350 |
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± |
kHz |
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Phase Margin at Unity±Gain (VO = 0.5 V to 3.5 V, RL = 2.0 kΩ) |
φm |
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± |
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65 |
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± |
deg. |
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Common Mode Rejection Ratio (VCC = 40 V) |
CMRR |
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65 |
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90 |
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± |
dB |
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Power Supply Rejection Ratio ( VCC = 33 V, VO = 2.5 V, RL = 2.0 kΩ) |
PSRR |
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± |
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100 |
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± |
dB |
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Output Sink Current (VO (Pin 3) = 0.7 V) |
IO± |
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0.3 |
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0.7 |
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± |
mA |
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Output Source Current (VO (Pin 3) = 3.5 V) |
IO+ |
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2.0 |
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±4.0 |
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± |
mA |
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PWM COMPARATOR SECTION (Test Circuit Figure 11) |
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Input Threshold Voltage (Zero Duty Cycle) |
VTH |
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± |
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2.5 |
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4.5 |
V |
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Input Sink Current (V(Pin 3) = 0.7 V) |
II± |
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0.3 |
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0.7 |
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± |
mA |
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DEADTIME CONTROL SECTION (Test Circuit Figure 11) |
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Input Bias Current (Pin 4) (VPin 4 = 0 V to 5.25 V) |
IIB (DT) |
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± |
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±2.0 |
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±10 |
μA |
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Maximum Duty Cycle, Each Output, Push±Pull Mode |
DCmax |
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% |
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(VPin 4 = 0 V, CT = 0.01 μF, RT = 12 kΩ) |
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45 |
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48 |
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50 |
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(VPin 4 = 0 V, CT = 0.001 μF, RT = 30 kΩ) |
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± |
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45 |
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50 |
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Input Threshold Voltage (Pin 4) |
Vth |
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V |
(Zero Duty Cycle) |
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± |
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2.8 |
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3.3 |
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(Maximum Duty Cycle) |
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0 |
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± |
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± |
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OSCILLATOR SECTION |
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Frequency (CT = 0.001 μF, RT = 30 kΩ) |
fosc |
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± |
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40 |
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± |
kHz |
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Standard Deviation of Frequency* (CT = 0.001 μF, RT = 30 kΩ) |
σfosc |
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± |
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3.0 |
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± |
% |
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Frequency Change with Voltage (VCC = 7.0 V to 40 V, TA = 25°C) |
fosc ( |
V) |
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± |
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0.1 |
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± |
% |
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Frequency Change with Temperature ( TA = Tlow to Thigh) |
fosc ( |
T) |
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± |
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± |
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12 |
% |
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(CT = 0.01 μF, RT = 12 kΩ) |
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UNDERVOLTAGE LOCKOUT SECTION |
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Turn±On Threshold (VCC increasing, Iref = 1.0 mA) |
Vth |
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5.5 |
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6.43 |
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7.0 |
V |
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TOTAL DEVICE |
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Standby Supply Current (Pin 6 at Vref, All other inputs and outputs open) |
ICC |
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mA |
(VCC = 15 V) |
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± |
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5.5 |
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10 |
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(VCC = 40 V) |
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± |
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7.0 |
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15 |
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Average Supply Current |
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mA |
(CT = 0.01 μF, RT = 12 kΩ, V(Pin 4) = 2.0 V) |
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± |
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7.0 |
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± |
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(VCC = 15 V) (See Figure 12) |
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N |
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* Standard deviation is a measure of the statistical distribution about the mean as derived from the formula, σ |
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Σ (Xn ± X)2 |
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n = 1 |
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N ± 1 |
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MOTOROLA ANALOG IC DEVICE DATA |
3 |
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TL494
Figure 1. Representative Block Diagram
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Output Control |
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VCC |
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13 |
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6 |
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8 |
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Oscillator |
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D |
Q |
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Q1 |
9 |
RT |
5 |
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Flip± |
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CT |
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Deadtime |
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Flop |
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Comparator |
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Ck |
Q |
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Q2 |
11 |
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0.12V |
± |
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+ |
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4 |
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10 |
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Deadtime |
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0.7V |
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Control |
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± |
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12 |
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± |
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+ |
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VCC |
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+ |
4.9V |
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0.7mA |
PWM |
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UV |
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Comparator |
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Lockout |
± |
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Reference |
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+ |
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+ |
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Regulator |
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+ |
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1 |
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2 |
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± |
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± |
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3.5V |
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1 |
2 |
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3 |
15 |
16 |
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14 |
7 |
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Error Amp |
Feedback PWM |
Error Amp |
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Ref. |
Gnd |
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1 |
Comparator Input |
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2 |
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Output |
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This device contains 46 active transistors.
Figure 2. Timing Diagram
Capacitor CT |
Feedback/PWM Comp. |
Deadtime Control |
Flip±Flop |
Clock Input |
Flip±Flop |
Q |
Flip±Flop |
Q |
Output Q1 |
Emitter |
Output Q2 |
Emitter |
Output |
Control |
4 |
MOTOROLA ANALOG IC DEVICE DATA |
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