Regulator. UC3578 Datasheet

UC3578 Datasheet PDF


Part Number

UC3578

Description

Buck Pulse Width Modulator Stepdown Voltage Regulator

Manufacture

Unitrode

Total Page 9 Pages
PDF Download
Download UC3578 Datasheet PDF


UC3578 Datasheet
Not Recommended for New Designs
application
INFO
available
Buck Pulse Width Modulator Stepdown Voltage Regulator
UC2578
UC3578
FEATURES
Provides Simple Single Inductor Buck
PWM Step-Down Voltage Regulation
Drives External High Side NMOS
Switch
14V to 72V Input Voltage Operating
Range
Contains 100kHz Internal Oscillator,
2V Reference and UVLO
Soft Start on Power Up
Overcurrent Shutdown Followed by
Soft Start
DESCRIPTION
The UC3578 is a PWM controller with an integrated high side floating gate
driver. It is used in buck step down converters and regulates a positive
output voltage. Intended to be used in a distributed power system, the IC
allows operation from 14V to 72V input voltage which range includes the
prevalent telecomm bus voltages. The output duty cycle of the UC3578
can vary between 0% and 90% for operation over the wide input voltage
and load conditions.
The UC3578 simplifies the design of the single switch PWM buck converter
by incorporating a floating high side driver for an external N-channel
MOSFET switch. It also features a 100kHz fixed frequency oscillator, an
internal 2V precision reference, an error amplifier configured for voltage
mode operation, and a PWM comparator with latching logic. Comple-
menting the traditional voltage mode control block, the UC3578 incorpo-
rates an overcurrent shutdown circuit with full cycle soft re-start to limit the
input current to a user defined maximum value during overload operation.
Additional functions include an under voltage lockout circuit to insure that
sufficient input supply voltage is present before any switching activity can
occur.
The UC2578 and the UC3578 are both available in surface mount and
thru-hole power packages.
TYPICAL APPLICATION DIAGRAM
ORDERING INFORMATION
UC2578DP
UC2578N
UC3578DP
UC3578N
TEMPERATURE RANGE
–40°C to +85°C
0°C to +70°C
PACKAGE
Power SOIC
Power PDIP
Power SOIC
Power PDIP
15-40 VIN
RSENSE
0.12
CS
1000pF
47µF
1N4148
RS
1k
IRFZ34
CGG
1µF
15
11 15 10
7
6
10
DIODE CS VGG OUT SRC
CCC
1µF
14 VCC
UC3578
EAINV 2
16 SS
GND GND GND GND EAOUT 3
4 5 12 13
CSS
LOUT
40µH
RECTIFIER
MBR 3100
1µF COUT
220µF
220pF
100k
2200pF
50k
R1
VOUT
5k
1k
05/99
UDG-99064

UC3578 Datasheet
Not Recommended for New Designs
ABSOLUTE MAXIMUM RATINGS
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +72V
EAINV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to +10V
EAOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to +10V
SS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to +10V
DIODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to VCC
VGG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to VCC +14V
CS . . . . . . . . . . . . . . . . . . . . . . . . . . . . VCC – 5V to VCC +0.6V
IOUT Pulsed . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.8A to +0.6A
SRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.6V to VCC
Storage Temperature . . . . . . . . . . . . . . . . . . . 65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C
Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C
Currents are positive into, negative out of the specified terminal.
Consult Packaging Section of Databook for thermal limitations
and considerations of packages.
CONNECTION DIAGRAM
DIL-16, SOIC-16 (Top View)
N or DP Packages
UC2578
UC3578
Note: The four GND pins are internally connected.
ELECTRICAL CHARACTERISTICS: Unless otherwise specified VCC = 14V, VGG = 14V, TA = TJ.
PARAMETER
TEST CONDITIONS
MIN TYP
Oscillator Section
Frequency
VCC = 14V to 72V, EAINV = 1.9V, TJ = 25°C
100 110
VCC = 11V to 14V, Over Temperature
90
Error Amplifier Section
EAINV
EAOUT = EAINV
1.97 2
IEAINV
EAOUT = EAINV
100
EAVOL
EAOUT/EAINV, 25°C
70 80
EAOUT High
EAOUT Low
EAINV 1.9V, IEAOUT = –100µA
EAINV 2.1V, IEAOUT = 100µA
5.5 6.2
0.8
Unity Gain Bandwidth
TJ = 25°C, F = 100kHz
0.85 1
PSRR, EAOUT
EAOUT = EAINV, VCC = 14V
80 90
Current Sense Comparator Section
Threshold (Referred to VCC)
0.4 0.5
Input Bias Current
CS = VCC – 0.4V
0.2
Propagation Delay
VOVERDRIVE = 250mV
0.7
Blanking Time
Gate Drive Output Section
VOVERDRIVE = 250mV
75 200
VOH
VOL
Rise Time
Fall Time
Pulse Width Modulator Section
IOUT = –200mA
IOUT = 20mA
IOUT = 200mA
TJ = 25°C, CLOAD = 1nF
TJ = 25°C, CLOAD = 1nF
9.5 11
0.2
1.5
40
40
Maximum Duty Cycle
EAINV 1.9V
85 90
Minimum Duty Cycle
EAINV 2.1V
0
Modulator Gain
EAOUT = 2.5V to 3.5V
30
Undervoltage Lockout Section
Start Threshold
OUT – SRC, EAINV 1.9V, SRC = 0V
10 11
UVLO Hysteresis
1.5 2
MAX UNITS
120 kHz
120 kHz
2.03 V
300 nA
dB
V
1.1 V
MHz
dB
0.6 V
1 µA
1.2 µs
300 ns
V
0.36 V
2V
70 ns
70 ns
%
%
%/V
12 V
2.5 V
2


Features Datasheet pdf Not Recommended for New Designs applica tion INFO available Buck Pulse Width M odulator Stepdown Voltage Regulator UC 2578 UC3578 FEATURES • Provides Simp le Single Inductor Buck PWM Step-Down V oltage Regulation • Drives External H igh Side NMOS Switch • 14V to 72V Inp ut Voltage Operating Range • Contains 100kHz Internal Oscillator, 2V Referen ce and UVLO • Soft Start on Power Up • Overcurrent Shutdown Followed by So ft Start DESCRIPTION The UC3578 is a P WM controller with an integrated high s ide floating gate driver. It is used in buck step down converters and regulate s a positive output voltage. Intended t o be used in a distributed power system , the IC allows operation from 14V to 7 2V input voltage which range includes t he prevalent telecomm bus voltages. The output duty cycle of the UC3578 can va ry between 0% and 90% for operation ove r the wide input voltage and load condi tions. The UC3578 simplifies the design of the single switch PWM buck converter by incorporating a floating high s.
Keywords UC3578, datasheet, pdf, Unitrode, Buck, Pulse, Width, Modulator, Stepdown, Voltage, Regulator, C3578, 3578, 578, UC357, UC35, UC3, stock, pinout, distributor, price, schematic, inventory, databook, Electronic, Components, Parameters, parts, cross reference, chip, Semiconductor, circuit, Electric, manual, substitute, Equivalent




@ 2014 :: Datasheetspdf.com ::
Semiconductors datasheet search & download site (Privacy Policy & Contact)