TEXAS INSTRUMENTS UCC2813-0, UCC2813-1, UCC2813-2, UCC2813-3, UCC2813-4 Technical data

...

application

INFO

available

UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5

Low Power Economy BiCMOS Current Mode PWM

FEATURES

100mA Typical Starting Supply Current

•

500mA Typical Operating Supply Current

•

Operation to 1MHz

•

Internal Soft Start

•

Internal Fault Soft Start

•

Internal Leading-Edge Blanking of the

•

Current Sense Signal 1 Amp Totem-Pole Output

•

70ns Typical Response from

•

Current-Sense to Gate Drive Output

1.5% Tolerance Voltage Reference

•

Same Pinout as UCC3802, UC3842, and

•

UC3842A

DESCRIPTION

The UCC3813-0/-1/-2/-3/-4/-5 family of high-speed, low-power inte grated circuits contain all of the control and drive components required for off-line and DC-to-DC fixed frequency current-mode switching power supplies with minimal parts count.

These devices have the same pin configuration as the UC3842/3/4/5 family, and also offer the added features of internal full-cycle soft start and internal leading-edge blanking of the current-sense input.

The UCC3813-0/-1/-2/-3/-4/-5 family offers a variety of package options, temperature range options, choice of maximum duty cycle, and choice of critical voltage levels. Lower reference parts such as the UCC3813-3 and UCC3813-5 fit best into battery operated systems, while the higher reference and the higher UVLO hysteresis of the UCC3813-2 and UCC3813-4 make these ideal choices for use in off-line power supplies.

The UCC2813-x series is specified for operation from –40°C to +85°C and the UCC3813-x series is specified for operation from 0°C to +70°C.

ORDERING INFORMATION

Part Number Maximum Duty Cycle Reference Voltage Turn-On Threshold Turn-Off Threshold

UCCx813-0 100% 5V 7.2V 6.9V UCCx813-1 50% 5V 9.4V 7.4V UCCx813-2 100% 5V 12.5V 8.3V UCCx813-3 100% 4V 4.1V 3.6V UCCx813-4 50% 5V 12.5V 8.3V UCCx813-5 50% 4V 4.1V 3.6V

BLOCK DIAGRAM

SLUS161A - APRIL 1999 - REVISED JANUARY 2005

UDG-96134

UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5

ABSOLUTE MAXIMUM RATINGS (Note 1)

VCC Voltage (Note 2) ........................... 12.0V

VCC Current................................. 30.0mA

OUT Current .................................. ±1.0A

OUT Energy (Capacitive Load) ................... 20.0mJ

Analog Inputs (FB, CS) ....................–0.3V to 6.3V

Power Dissipation at T Power Dissipation at T

Storage Temperature ...................–65°C to +150°C

Junction Temperature...................–55°C to +150°C

Lead Temperature (Soldering, 10 Seconds)......... +300°C

Note 1: All voltages are with respect to GND. All currents are positive into the specified terminal. Consult Unitrode Integrated Circuits databook for information regarding thermal specifica tions and limitations of packages. Note 2: In normal operation VCC is powered through a current limiting resistor. Absolute maximum of 12V applies when VCC is driven from a low impedance source such that ICC does not exceed 30mA. The resistor should be sized so that the VCC voltage under operating conditions is below 12V but above the turn off threshold.

UCC2813 –40°C TO +85°C N, D, PW UCC3813 0°C TO +70°C N, D, PW

< +25°C (N Package)......... 1.0W

< +25°C (D Package)........ 0.65W

TEMPERATURE RANGE PACKAGES

CONNECTION DIAGRAMS

DIL-8 or SOIC-8 (TOP VIEW) N or D PACKAGE

COMP

TSSOP-8 (TOP VIEW) PW PACKAGE

COMP

REF

VCC

OUT

GND

REF

VCC

OUT

ORDERING INFORMATION

UCC

813

–

GND

PRODUCT OPTION

PACKAGE

TEMPERATURE RANGE

ELECTRICAL CHARACTERISTICSUnless otherwise stated, these specifications apply for –40°C £ T

UCC2813-x; 0°C £ T

0.1mF capacitor from VCC to GND; 0.1mF capacitor from VREF to GND. T

£ +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND;

A=TJ

£ +85°C for

UCC2813-x

PARAMETER TEST CONDITIONS

UCC3813-x

MIN TYP MAX

Reference Section

Output Voltage T

= +25°C, I = 0.2mA, UCCx813-0/-1/-2/-4 4.925 5.00 5.075 V

= +25°C, I = 0.2mA, UCCx813-3/-5 3.94 4.00 4.06 V

Load Regulation 0.2mA <I<5mA 10 30 mV Total Variation UCCx813 -0-1/-2/-4 (Note 7) 4.84 5.00 5.10 V

UCCx813-5 (Note 7) 3.84 4.00 4.08 V Output Noise Voltage 10Hz £ f £ 10kHz, T Long Term Stability T

= +125°C, 1000 Hours (Note 9) 5 mV

= +25°C (Note 9) 70 mV

Output Short Circuit –5 –35 mA

Oscillator Section

Oscillator Frequency UCCx813-0/-1/-2/-4 (Note 4) 40 46 52 kHz

UCCx813-3/-5 (Note 4) 26 31 36 kHz Temperature Stability (Note 9) 2.5 % Amplitude Peak-to-Peak 2.25 2.40 2.55 V Oscillator Peak Voltage 2.45 V

UNITS

UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5

ELECTRICAL CHARACTERISTICS

UCC2813-x; 0°C £ T

0.1mF capacitor from VCC to GND; 0.1mF capacitor from VREF to GND. T

Error Amplifier Section

Input Voltage COMP = 2.5V; UCCx813-0/-1/-2/-4 2.42 2.50 2.56 V

Input Bias Current Open Loop Voltage Gain 60 80 dB COMP Sink Current FB = 2.7V, COMP = 1.1V 0.4 2.5 mA COMP Source Current FB = 1.8V, COMP = REF – 1.2V –0.2 –0.5 –0.8 mA Gain Bandwidth Product (Note 9) 2 MHz

PWM Section

Maximum Duty Cycle UCCx813-0/-2/-3 97 99 100 %

Minimum Duty Cycle COMP = 0V 0 %

Current Sense Section

Gain (Note 5) 1.10 1.65 1.80 V/V Maximum Input Signal COMP = 5V (Note 6) 0.9 1.0 1.1 V Input Bias Current CS Blank Time 50 100 150 ns Over-Current Threshold 1.32 1.55 1.70 V COMP to CS Offset CS = 0V 0.45 0.90 1.35 V

Output Section

OUT Low Level I = 20mA, all parts 0.1 0.4 V

OUT High V (VCC-OUT)

Rise Time C Fall Time C

Undervoltage Lockout Section

Start Threshold (Note 8) UCCx813-0 6.6 7.2 7.8 V

Stop Threshold (Note 8) UCC1813-0 6.3 6.9 7.5 V

Start to Stop Hysteresis UCCx813-0 0.12 0.3 0.48 V

SAT

£ +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND;

PARAMETER TEST CONDITIONS

Unless otherwise stated, these specifications apply for –40°C £ TA£ +85°C for

A=TJ

UCC2813-x UCC3813-x

MIN TYP MAX

COMP = 2.0V; UCCx813-3/-5 1.92 2.0 2.05 V

–22mA

UCCx813-1/-4/-5 48 49 50 %

–200 200 nA

I = 200mA, all parts 0.35 0.90 V I = 50mA, VCC = 5V, UCCx813-3/-5 0.15 0.40 V I = 20mA, VCC = 0V, all parts 0.7 1.2 V I = –20mA, all parts 0.15 0.40 V I = –200mA, all parts 1.0 1.9 V I = –50mA,VCC = 5V, UCCx813-3/-5 0.4 0.9 V

= 1nF 41 70 ns

= 1nF 44 75 ns

UCCx813-1 8.6 9.4 10.2 V UCCx813-2/-4 11.5 12.5 13.5 V UCCx813-3/-5 3.7 4.1 4.5 V

UCC1813-1 6.8 7.4 8.0 V UCCx813-2/-4 7.6 8.3 9.0 V UCCx813-3/-5 3.2 3.6 4.0 V

UCCx813-1 1.6 2 2.4 V UCCx813-2/-4 3.5 4.2 5.1 V UCCx813-3/-5 0.2 0.5 0.8 V

UNITS

UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5

ELECTRICAL CHARACTERISTICS

UCC2813-x; 0°C £ T

0.1mF capacitor from VCC to GND; 0.1mF capacitor from VREF to GND. T

Soft Start Section

COMP Rise Time FB = 1.8V, Rise from 0.5V to REF–1V 4 ms

Overall Section

Start-up Current VCC < Start Threshold 0.1 0.23 mA Operating Supply Current FB = 0V, CS = 0V, RC = 0V 0.5 1.2 mA VCC Internal Zener Voltage ICC = 10mA (Note 8) 12 13.5 15 V VCC Internal Zener Voltage Minus Start

Threshold Voltage

Note 3: Adjust VCC above the start threshold before setting at 10V. Note 4: Oscillator frequency for the UCCx813-0, UCCx813-2 and UCCx813-3 is the output frequency.

Oscillator frequency for the UCCx813-1, UCCx813-4 and UCCx813-5 is twice the output frequency.

Note 5: Gain is defined by:

Note 6: Parameter measured at trip point of latch with Pin 2 at 0V. Note 7: Total Variation includes temperature stability and load regulation. Note 8: Start Threshold, Stop Threshold and Zener Shunt Thresholds track one another. Note 9: Ensured by design. Not 100% tested in production.

£ +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND;

PARAMETER TEST CONDITIONS

COMP

=££

Unless otherwise stated, these specifications apply for –40°C £ TA£ +85°C for

A=TJ

UCC2813-x UCC3813-x

MIN TYP MAX

UCCx813-2/-4 0.5 1.0 V

008.

UNITS

PIN DESCRIPTIONS

COMP: COMP is the output of the error amplifier and the

input of the PWM comparator. Unlike other devices, the error amplifier in the UCC3813

family is a true, low output-impedance, 2MHz operational amplifier. As such, the COMP terminal can both source and sink current. However, the error amplifier is internally current limited, so that you can command zero duty cycle by externally forcing COMP to GND.

The UCC3813 family features built-in full cycle Soft Start. Soft Start is implemented as a clamp on the maximum COMP voltage.

FB: FB is the inverting input of the error amplifier. For best stability, keep FB lead length as short as possible and FB stray capacitance as small as possible.

CS: CS is the input to the current sense comparators. The UCC3813 family has two different current sense comparators: the PWM comparator and an over-current comparator.

The UCC3813 family contains digital current sense filter ing, which disconnects the CS terminal from the current

sense comparator during the 100ns interval immediately following the rising edge of the OUT pin. This digital filter ing, also called leading-edge blanking, means that in most applications, no analog filtering (RC filter) is re quired on CS. Compared to an external RC filter tech nique, the leading-edge blanking provides a smaller effective CS to OUT propagation delay. Note, however, that the minimum non-zero On-Time of the OUT signal is directly affected by the leading-edge-blanking and the CS to OUT propagation delay.

The over-current comparator is only intended for fault sensing, and exceeding the over-current threshold will cause a soft start cycle.

RC: RC is the oscillator timing pin. For fixed frequency operation, set timing capacitor charging current by con necting a resistor from REF to RC. Set frequency by con necting a timing capacitor from RC to GND. For best performance, keep the timing capacitor lead to GND as short and direct as possible. If possible, use separate ground traces for the timing capacitor and all other func

tions.

PIN DESCRIPTIONS (cont.)

The frequency of oscillation can be estimated with the following equations:

UCCx813-0/-1/-2/-4:

UCCx813-3, UCCx813-5:

where frequency is in Hz, resistance is in W, and capaci tance is in farads. The recommended range of timing re sistors is between 10k and 200k and timing capacitor is 100pF to 1000pF. Never use a timing resistor less than 10k.

GND: GND is reference ground and power ground for all functions on this part.

OUT:OUT is the output of a high-current power driver ca pable of driving the gate of a power MOSFET with peak currents exceeding ±750mA. OUT is actively held low when VCC is below the UVLO threshold.

The high-current power driver consists of FET output devices, which can switch all of the way to GND and all of the way to VCC. The output stage also provides a very low impedance to overshoot and undershoot. This means that in many cases, external schottky clamp diodes are not required.

VCC: VCC is the power input connection for this device. In normal operation VCC is powered through a current limiting resistor. Although quiescent VCC current is very

15.

10.

UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5

low, total supply current will be higher, depending on OUT current. Total VCC current is the sum of quiescent VCC current and the average OUT current. Knowing the operating frequency and the MOSFET gate charge (Qg), average OUT current can be calculated from:

=·

IQF

OUT g

To prevent noise problems, bypass VCC to GND with a

0.1 mF ceramic capacitor in parallel as close to the VCC

pin as possible. An electrolytic capacitor may also be used in addition to the ceramic capacitor.

REF: REF is the voltage reference for the error amplifier and also for many other functions on the IC. REF is also used as the logic power supply for high speed switching logic on the IC.

When VCC is greater than 1V and less than the UVLO threshold, REF is pulled to ground through a 5kW resis tor. This means that REF can be used as a logic output indicating power system status. It is important for reference stability that REF is bypassed to GND with a ceramic capacitor as close to the pin as possible. An electrolytic capacitor may also be used in addition to the ceramic capacitor. A minimum of 0.1mF ceramic is required. Additional REF bypassing is required for external loads greater than 2.5mA on the reference.

To prevent noise problems with high speed switching transients, bypass REF to ground with a ceramic capacitor very close to the IC package.

APPLICATION INFORMATION

UDG-96139

The UCC3813-0/-1/-2/-3/-4/-5 oscillator generates a sawtooth waveform on RC. The rise time is set by the time constant of R and CT. The fall time is set by CT and an internal transistor on-resistance of approximately 125W. During the fall time, the out put is off and the maximum duty cycle is reduced below 50% or 100% depending on the part number. Larger timing capacitors increase the discharge time and reduce the maximum duty cycle and frequency.

Figure 1. Oscillator.

APPLICATION INFORMATION (cont.)

REF

V (V)

UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5

4.00

3.98

3.96

3.94

3.92

3.90

3.88

3.86

3.84

1000

100pF

100

200pF

Oscillator Freq. (kHz)

330pF

1nF

10 100 1000

R(k)

Figure 3. UCC3813-0/-1/-2/-4 oscillator frequency vs. R and C

100

99.5 99

98.5 98

97.5 97

96.5

Maximum Duty Cycle (%)

95.5 95

10 100 1000

Oscillator Frequency (kHz)

C = 200pF

C = 330pF

C = 100pF

Figure 4. UCC3813-0/-2/-3 max. duty cycle vs. oscillator frequency.

3.82

V (V)

vs. VCC;I

REF

5.2 5.4 5.6 5.8 6

LOAD

4 4.2 4.4 4.6 4.8

Figure 5. UCC3813-3/-5 V

1000

100

Oscillator Freq. (kHz)

100pF

200pF 330pF

1nF

10 100 1000

R(k)

Figure 6. UCC3813-3/-5 oscillator frequency vs. RTand

49.5

48.5

47.5

Maximum Duty Cycle (%)

46.5 10 100 1000

Oscillator Frequency (kHz)

C = 200pF

C = 330pF

C = 100pF

Figure 7. UCC3813-1/-4/-5 max. duty cycle vs. oscillator frequency.

= 0.5mA.Figure 2. Error amplifier gain/phase response.

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