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

•100 A Typical Starting Supply Current

•500 A 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

ORDERING INFORMATION

DESCRIPTION

The UCC3813-0/-1/-2/-3/-4/-5 family of high-speed, low-power integrated 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.

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

UDG-96134

SLUS161A - APRIL 1999 - REVISED JANUARY 2005

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) . . . . . . . . . . . . . . . . . . . 20.0 J Analog Inputs (FB, CS) . . . . . . . . . . . . . . . . . . . . –0.3V to 6.3V Power Dissipation at TA < +25°C (N Package). . . . . . . . . 1.0W Power Dissipation at TA < +25°C (D Package). . . . . . . . 0.65W 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 specifications 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.

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

ORDERING INFORMATION

UCC 813 –

PRODUCT OPTION

PACKAGE

TEMPERATURE RANGE

CONNECTION DIAGRAMS

DIL-8 or SOIC-8 (TOP VIEW)

N or D PACKAGE

COMP					REF
	1			8
					VCC
FB	2			7
CS	3			6	OUT
					GND
RC	4			5

TSSOP-8 (TOP VIEW)
PW PACKAGE
1	COMP	REF	8
2	FB	VCC	7
3	CS	OUT	6
4	RC	GND	5

ELECTRICAL CHARACTERISTICSUnless otherwise stated, these specifications apply for –40°C TA +85°C for UCC2813-x; 0°C TA +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND; 0.1 F capacitor from VCC to GND; 0.1 F capacitor from VREF to GND. TA = TJ.

		UCC2813-x
PARAMETER	TEST CONDITIONS	UCC3813-x			UNITS
		MIN	TYP	MAX
Reference Section
Output Voltage	TJ = +25°C, I = 0.2mA, UCCx813-0/-1/-2/-4	4.925	5.00	5.075	V
	TJ = +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, TJ = +25°C (Note 9)		70		V
Long Term Stability	TA = +125°C, 1000 Hours (Note 9)		5		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

2

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

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

ELECTRICAL CHARACTERISTICSUnless otherwise stated, these specifications apply for –40°C TA +85°C for UCC2813-x; 0°C TA +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND; 0.1 F capacitor from VCC to GND; 0.1 F capacitor from VREF to GND. TA = TJ.

		UCC2813-x
PARAMETER	TEST CONDITIONS	UCC3813-x			UNITS
		MIN	TYP	MAX
Error Amplifier Section
Input Voltage	COMP = 2.5V; UCCx813-0/-1/-2/-4	2.42	2.50	2.56	V
	COMP = 2.0V; UCCx813-3/-5	1.92	2.0	2.05	V
Input Bias Current		–2		2	A
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	%
	UCCx813-1/-4/-5	48	49	50	%
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		–200		200	nA
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
	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
OUT High VSAT	I = –20mA, all parts		0.15	0.40	V
(VCC-OUT)	I = –200mA, all parts		1.0	1.9	V
	I = –50mA,VCC = 5V, UCCx813-3/-5		0.4	0.9	V
Rise Time	CL = 1nF		41	70	ns
Fall Time	CL = 1nF		44	75	ns
Undervoltage Lockout Section
Start Threshold (Note 8)	UCCx813-0	6.6	7.2	7.8	V
	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
Stop Threshold (Note 8)	UCC1813-0	6.3	6.9	7.5	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
Start to Stop Hysteresis	UCCx813-0	0.12	0.3	0.48	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

3

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

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

ELECTRICAL CHARACTERISTICSUnless otherwise stated, these specifications apply for –40°C TA +85°C for UCC2813-x; 0°C TA +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND; 0.1 F capacitor from VCC to GND; 0.1 F capacitor from VREF to GND. TA = TJ.

							UCC2813-x
PARAMETER					TEST CONDITIONS		UCC3813-x			UNITS
						MIN		TYP	MAX
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					UCCx813-2/-4	0.5		1.0		V
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:	A	VCOMP		0 VCS 0.8V.

VCS

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.

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 filtering, 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 filtering, also called leading-edge blanking, means that in most applications, no analog filtering (RC filter) is required on CS. Compared to an external RC filter technique, 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 connecting a resistor from REF to RC. Set frequency by connecting 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 functions.

4

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

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

PIN DESCRIPTIONS (cont.)

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

UCCx813-0/-1/-2/-4: F 1.5

R C

UCCx813-3, UCCx813-5: F 1.0

R C

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:

IOUT Qg F.

	where frequency is in Hz, resistance is in , and capaci-	To prevent noise problems, bypass VCC to GND with a
		0.1 F ceramic capacitor in parallel as close to the VCC
	tance is in farads. The recommended range of timing re-	pin as possible. An electrolytic capacitor may also be
	sistors is between 10k and 200k and timing capacitor is	used in addition to the ceramic capacitor.
	100pF to 1000pF. Never use a timing resistor less than	REF: REF is the voltage reference for the error amplifier
	10k.
		and also for many other functions on the IC. REF is also
	GND: GND is reference ground and power ground for all
		used as the logic power supply for high speed switching
	functions on this part.	logic on the IC.
	OUT: OUT is the output of a high-current power driver ca-	When VCC is greater than 1V and less than the UVLO
	pable of driving the gate of a power MOSFET with peak	threshold, REF is pulled to ground through a 5k resis-
	currents exceeding 750mA. OUT is actively held low	tor. This means that REF can be used as a logic output
	when VCC is below the UVLO threshold.	indicating power system status. It is important for refer-
	The high-current power driver consists of FET output de-	ence stability that REF is bypassed to GND with a ce-
	vices, which can switch all of the way to GND and all of	ramic capacitor as close to the pin as possible. An
	the way to VCC. The output stage also provides a very	electrolytic capacitor may also be used in addition to the
	low impedance to overshoot and undershoot. This	ceramic capacitor. A minimum of 0.1 F ceramic is re-
	means that in many cases, external schottky clamp di-	quired. Additional REF bypassing is required for external
	odes are not required.	loads greater than 2.5mA on the reference.

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

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 RT and CT. The fall time is set by CT and an internal transistor on-resistance of approximately 125 . During the fall time, the output 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.

5

APPLICATION INFORMATION (cont.)

(V)REF 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

3.82

4

4.2

4.4

4.6

4.8

5

5.2

5.4

5.6

5.8

6

VCC (V)

Figure 2. Error amplifier gain/phase response.

	1000
Freq.(kHz)		100pF
Oscillator	100
		200pF
		330pF
		1nF
	10
	10	100	1000
		RT (k )
Figure 3. UCC3813-0/-1/-2/-4 oscillator frequency vs. RT
and CT.
	100
	99.5
(%)	99
Cycle	98.5		C
			T
	98	C	=
		T
Duty		=
		C	100pF
	97.5	T
		=
		200pF
Maximum	97	330pF
	96.5
	96
	95.5
	95
	10	100	1000
	Oscillator	Frequency (kHz)
Figure 4. UCC3813-0/-2/-3		max. duty cycle vs. oscillator
frequency.

Figure 5. UCC3813-3/-5 VREF vs. VCC; ILOAD = 0.5mA.
	1000
Freq.(kHz)
Oscillator	100	100pF
		200pF
		330pF
	10	1nF
	10	100	1000
		RT (k )
Figure 6. UCC3813-3/-5 oscillator frequency vs. RT and
CT.
	50
(%)	49.5
	49
Cycle
			C
			T
		C	=
	48.5	T
Duty		=
		C	100pF
		T
		=
		200pF
Maximum	48	330pF
	47.5
	47
	46.5
	10	100	1000
	Oscillator Frequency (kHz)
Figure 7. UCC3813-1/-4/-5		max. duty cycle vs. oscillator
frequency.

6