Texas Instruments UCC3839N, UCC3839DTR, UCC3839D, UCC2839N, UCC2839DTR Datasheet

UCC1839

UCC2839

UCC3839

Secondary Side Average Current Mode Controller

FEATURES

∙Practical Secondary Side Control of Isolated Power Supplies

∙Provides a Self Regulating Bias Supply From a High Input Voltage Using an External N-Channel Depletion Mode FET

∙Onboard Precision, Fixed Gain, Differential Current Sense Amplifier

∙Wide Bandwidth Current Error Amplifier

∙5V Reference

∙High Current, Programmable Gm Amplifier Optimized to Drive Opto-couplers

DESCRIPTION

The UCC3839 provides the control functions for secondary side average current mode control in isolated power supplies. Start up, pulse width modulation and MOSFET drive must be accomplished independently on the primary side. Communication from secondary to primary side is anticipated through an opto-isolator.

Accordingly, the UCC3839 contains a fixed gain current sense amplifier, voltage and current error amplifiers, and a Gm type buffer/driver amplifier for the opto-isolator. Additional housekeeping functions include a precision 5V reference and a bias supply regulator.

Power for the UCC3839 can be generated by peak rectifying the voltage of the secondary winding of the isolation transformer. From this unregulated voltage, the UCC3839’s bias supply regulator will generate its own 7.5V bias supply using an external, N-channel, depletion mode FET.

The UCC3839 can be configured for traditional average current mode control where the output of the voltage error amplifier commands the current error amplifier. It can also be configured for output voltage regulation with average current mode short circuit current limiting, employing two parallel control loops regulating the output voltage and output current independently.

BLOCK DIAGRAM

UDG-97011

04/99

ABSOLUTE MAXIMUM RATINGS

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15V Supply Current

(LED not connected) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2mA (LED connected) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14mA Analog Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to 15V

Power Dissipation at TA = 60°C

(LED not connected). . . . . . . . . . . . . . . . . . . . . . . . . . 20mW (LED connected). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55mW Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C Junction Temperature. . . . . . . . . . . . . . . . . . . –55°C to +150°C Lead Temperature (Soldering, 10sec.) . . . . . . . . . . . . . +300°C

Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of package.

UCC1839

UCC2839

UCC3839

CONNECTION DIAGRAMS

DIL-14, SOIC-14 (Top View)

J or N Package, D Package

ELECTRICAL CHARACTERISTICS: Unless otherwise specified, 0°C to 70°C for the UCC3839, –40°C to 85° for the UCC2839 and –55°C to 125°C for the UCC1839. V LINE = 10V, RG = 400Ω. TA = TJ.

PARAMETER	TEST CONDITIONS	MIN	TYP	MAX	UNITS
Current Error Amplifier
VIO				10	mV
AVOL		60			dB
CMRR	VCM = 0.5V to 5.5V	60			dB
PSRR	VLINE = 10V to 20V	60			dB
CAO High	CA– = 1V, CA+ = 1.1V, ICAO = –100μA	4.8		7	V
ICAO	CA– = 1V, CA+ = 1.1V, CAO = 0.5V	–500		–250	μA
CAO Low	CA– = 1V, CA+ = 0.9V, ICAO = 500μA		0.2	0.4	V
GBW	F = 100kHz, TA = 25°C	3	5		MHz
Voltage Error Amplifier
VA–		1.475	1.5	1.525	V
AVOL		60			dB
PSRR	VLINE = 10V to 20V	60			dB
VAO High	IVAO = –100μA to 100μA	4.8	5	5.2	V
IVAO	VA– = 1.45V, VAO = 0.5V	–500		–250	μA
VAO Low	VA– = 1.55V, VAO = 0.5V, IVAO = 500μA		0.2	0.4	V
GBW	(Note 1)	3	5		MHz
Current Sense Amplifier
CSO Zero	CS+ = CS– = –0.3V to 5.5V, ICSO = –100μA to 100μA	0.95	1	1.05	V
AV	CS+ = 0, CS– = 0mV to –200mV	7.8	8	8.2	V/V
Current Sense Amplifier (cont.)
Slew Rate	CS+ = 0, CS– = 0mV to –0.5V	2	4		V/μs
CSO	CS+ = –200mV, CS– = –700mV	4.8	5	5.2	V
LED Driver
ILED	LED = 5.5V, CA– = 1V, CA+ = 1.1V, RG = 400		0	10	μA
	LED = 5.5V, CA– = 1V, CA+ = 0.9V, RG = 400	9	10	11	mA
Gm	LED = 5.5V, CAO = 1V to 3V, RG = 400	2.25	2.5	2.75	mS
Slew Rate	CAO = 2V to 2.5V, LED = 400Ω to 5.5V, RG = 400	2	4		V/μs

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