TC25C25 Datasheet, PDF (7/7 Pages) TelCom Semiconductor, Inc – BICMOS PWM CONTROLLERS

BICMOS PWM CONTROLLERS
BENCH TEST OPERATIONAL SIMULATION
WAVEFORMS
3V
CT
PIN 5 _0.5V
PIN 2
VOLTAGE
OSC OUT
PIN 4
DEAD TIME
OUTPUT A
PIN 11
OUTPUT B
PIN 14
1
TC25C25
TC35C25
MET
1000pF
GND
0 to 1k
1 IN–
2 IN+
3 SYNC
4 OSC OUT
5 CT
6 RT
7 DISCH
8 SOFT
VREF 16
VIN 15
OUTB 14
VDD 13
GND 12
OUTA 11
SHDN 10
CMPTR 9
2
MET
+
.1µf
–
V011
16V
3
GND
The 5k potentiometer sets a reference voltage at pin 2.
When ramp voltage of pin 5 reaches this reference voltage,
output drive pulse is active ON. Varying the discharge
resistor will vary the dead time. Increasing the discharge
resistor will effect an increase in the dead time.
4 REPLACING BIPOLAR VERSIONS WITH CMOS
Although the pin-out and functions are the same for both
the Bipolar and CMOS versions, there are several differ-
ences that need to be taken into account. The reference
voltage on the TC35C25 is 4V instead of 5V and the
oscillator ramp is 3V, not 4V. The R_T and C_T values are
different for any particular frequency and dead-time require-
ment.
The most important difference is that the absolute
maximum rating of the V_DD and V_IN voltages for the TC35C25
5
is 18V, whereas the UC3525 is 40V.
TYPICAL CHARACTERISTICS
Oscillator Frequency
vs. Ct and Rt
900
800
VDD = VIN = 16V, TA +25°C
700
Rt = 1k
600
Rt = 2k
Rt = 5k
500
Rt = 10k
400
Rt = 20k
300
200
100
Supply Current
vs. Frequency
40
35 ^{VDD = 16V, TA +25°C}
30 ^{CL = 2200pF}
25 ^{CL = 1000pF}
20 ^{CL = 470pF}
CL = 10pF
15
10
5
Dead Time
vs. Ct and Discharge Resistor
3000
6
2500
2000
VDD = 16V, TA +25°C, Rt = 10k
Ct = 1000pF
Ct = 500pF
1500 ^{Ct = 330pF}
Ct = 100pF
1000
7
500
0
0
200
400
600
800 1000
0 0.2 0.4 0.6 0.8 1
Ct (pF)
FREQUENCY (MHz)
0
0
200 400 600 800 1000
DISCHARGE RESISTOR (Ω)
8
TELCOM SEMICONDUCTOR, INC.
4-117