UC2578
UC3578
ELECTRICAL CHARACTERISTICS: Unless otherwise specified VCC = 14V, VGG = 14V, TA = TJ.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX UNITS
VGG Regulator Section
VGG – SRC
VCC = 72V, SRC = 0V, IVGG = –7mA
VCC = 50V, SRC = 0V, IVGG = –7mA
VCC = 15V, SRC = 0V, IVGG = –7mA
VCC = 11V, SRC = 0V, IVGG = –7mA
14.5 15.25
17
16
V
V
V
V
14
13
14.75
13.75 14.5
9.5
10
10.5
Soft Start Ramp Section
Soft Start Ramp Current
Supply Current Section
IVCC
–30
–45
µA
EAINV ≥ 2.1V, SRC = 0V
EAINV ≥ 2.1V, SRC = 0V
10
7
14
mA
mA
IVGG
10.5
PIN DESCRIPTIONS
CS: Peak current limit sense pin. Senses the current OUT: Gate drive for the external NMOS switch
across a current sense resistor placed between VCC and connected between VCC and the buck inductor.
the drain of the NMOS buck switch. OUT will be held low
SRC: This pin is connected to the junction of the external
(NMOS buck switch off) if VCC – CS exceeds 0.5V.
NMOS switch source, the floating voltage source
DIODE: An external small signal diode (1N4148 typical)
is connected here, anode to VCC and cathode to
DIODE, to implement the VGG regulator function.
capacitor, the free-wheeling diode cathode, and buck
inductor.
SS: The external soft start capacitor is connected to this
pin.
EAINV: Inverting input to error amplifier. V
sense
OUT
feedback is connected to this pin. The non-inverting input
of the error amplifier is internally connected to 2V.
VGG: An external capacitor connected from VGG to
SRC completes the floating voltage source for the
floating gate driver. A 1µF capacitor is recommended.
EAOUT: Output of the error amplifier. Use EAOUT and
EAINV for loop compensation components.
VCC: Input supply voltage. This pin supplies an internal
ground referenced voltage regulator that supplies the IC
and an on-chip regulated floating voltage source (VGG –
SRC) used by the floating driver to drive the external
NMOS buck switch. This pin should be bypassed with a
high quality ceramic capacitor.
GND: Circuit Ground. The four ground pins are internally
connected together by the fused leadframe of the
package. They provide the primary thermal conduction
path for dissipating junction heat.
APPLICATION INFORMATION
The UC3578 Floating Buck Controller is a high frequency through a small resistor, as shown in the typical applica-
switching regulator with a floating driver which provides tion diagram and in Fig 2. This capacitor provides the en-
PWM control for non-isolated buck converters. The con- ergy for the high side driver. The gate drive voltage to
troller operates at a fixed 100 kHz switching frequency, the MOSFET is internally regulated to 14V. A diode
and in voltage mode control. The duty cycle range of the (1N4148) is required from the input voltage to DIODE.
PWM output is 0% to 90% allowing for a wide range of This allows the floating drive capacitor to charge during
input voltages (14V minimum with transients to 72V). conduction of the output rectifier but prevents its dis-
The regulator features an undervoltage lockout threshold
of 11V with approximately 2V hysterisis as well as soft
start capability. The typical application circuit shown is for
a 15V to 40V input and a 12V at 3A output.
charge back into the supply rail. A 1µF ceramic capacitor
is recommended from VCC to ground to provide high fre-
quency decoupling. Additional decoupling of this pin
could be accomplished by a low value resistor between
VCC and V and a 1µF capacitor from VCC to GND as
shown in the schematic.
IN
To ensure proper operation of the floating driver, an ex-
ternal capacitor (1µF ceramic) must be connected from
VGG to SRC, and to the source of the external MOSFET
3
5秒后页面跳转
NTC热敏电阻与PTC热敏电阻的应用原理及应用范围
GTO与普通晶闸管相比为什么可以自关断？为什么普通晶闸管不能呢？从GTO原理、应用范围带你了解原因及推荐型号
LF353数据手册解读：特性、应用、封装、引脚说明、电气参数及替换型号推荐
A4950资料手册解读：特性、应用、封装、引脚功能、电气参数及代换型号
微信公众号
抖音公众号
浙公网安备 33010502006866号 浙ICP备10014259号-119
营业执照ICP证
技术参数
数据手册
如果您发现信息不准确，
