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參數(shù)資料
| 型號： | UC1827-2 |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | Buck Current/Voltage Fed Push-Pull PWM Controllers |
| 中文描述： | 降壓電流/電壓美聯(lián)儲推挽式PWM控制器 |
| 文件頁數(shù)： | 4/15頁 |
| 文件大小： | 283K |
| 代理商： | UC1827-2 |
www.ti.com
(1)
f
OSC
0.77
R
RT
R
DELAY
200
2.5 V
R
RT
C
CT
(Hz)
(2)
t
DELAY
10
9
(s)
(3)
I
RT
UC1827-1, UC1827-2
UC2827-1, UC2827-2
UC3827-1, UC3827-2
SLUS365A–APRIL 1999–REVISED AUGUST 2005
Terminal Functions
TERMINAL
N or
DW
I/O
DESCRIPTION
NAME
Q
Output of the buck PWM controller. The BUCK output is a floating driver, optimized for controlling the
gate of an N-channel MOSFET. The peak sink and source currents are 1 A. V
CC
undervoltage faults
disables BUCK to an off condition (low).
Non-inverting input of the current error amplifier.
Inverting input of the current error amplifier
Output of the current error amplifier and the inverting input of the PWM comparator of the buck
converter.
Noninverting input of the current sense amplifier.
Inverting input of the current sense amplifier.
Output of the current sense amplifier and the noninverting input of the current limit comparator. When
the signal level on this pin exceeds the 3V threshold of the current limit comparator, the buck gate drive
pulse is terminated. This feature is useful to implement cycle-by-cycle current limiting for the buck
converter.
Provides for the timing capacitor which is connected between CT and GND. The oscillator frequency is
set by CT and a resistor RT, connected between pin RT and GND. The CT discharge current is
approximately 40 x the bias current through the resistor connected to RT. A practical maximum value for
the discharge current is 20 mA. The frequency of the oscillator is given by equation
(1)
A resistor to GND programs the overlap time of the PUSH and PULL outputs of the UC3827-1 and the
dead time of the PUSH and PULL outputs of the UC3827-2. The minimum value of the resistor, R
DELAY
,
is 18 k
. The delay or overlap time is given by equation
(2)
Ground reference for all sensitive setup components not related to driving the outputs. They include all
timing, voltage sense, current sense, and bypass components.
Ground connection for the PUSH and PULL outputs. PGND must be connected to GND at a single point
on the printed circuit board. This is imperative to prevent large, high frequency switching currents
flowing through the ground metalization inside the device.
Ground referenced output to drive an N-channel MOSFET. The PULL and the PUSH outputs are driving
the two switches of the push-pull converter with complementary signals at close to a 50% duty cycle.
Any undervoltage faults will disable PULL to an off condition (low).
Ground referenced output to drive an N-channel MOSFET. The PULL and the PUSH outputs are driving
the two switches of the push-pull converter with complementary signals at close to a 50% duty cycle.
Any undervoltage faults disables PUSH to an off condition (low).
The RAMP voltage, after a 700 mV internal level shift, is fed to the noninverting input of the buck PWM
comparator. A resistor to V
and a capacitor to GND provide an input voltage feedforward signal for the
buck controller in voltage mode control. In peak current mode control, the RAMP pin receives the
current signal of the buck converter. In an average current mode setup, the RAMP pin has a linearly
increasing ramp signal. This waveform may be generated either by connecting RAMP directly to CT, or
by connecting both a resistor from VCC to RAMP and a capacitor from RAMP to GND.
The output of the +5V on board reference. Bypass this pin with a capacitor to GND. The reference is off
when the chip is in undervoltage lockout mode.o
A resistor to GND programs the charge current of the timing capacitor connected to CT. The charge
current approximately equals that shown in equation
(3)
. The charge current should be less than 500 μA
to keep CT's discharge peak current less than 20 mA, which is CT's maximum practical discharge value.
The discharge time, which sets the maximum duty cycle, is set internally and is influenced by the charge
current.
The source connection for the floating buck switch. The voltage on the SRC pin can exceed VCC but
must be lower than 90 V–V
VCC
. Also, during turn-off transients of the buck switch, the voltage at SRC
can go to –2V.
BUCK
2
3
O
CEA+
CEA-
12
13
13
14
I
I
CEAO
6
7
O
CSA+
CSA–
8
9
9
10
I
I
CSAO
7
8
O
CT
18
20
I
DELAY
20
22
I
GND
11
12
-
PGND
21
25
-
PULL
22
26
O
PUSH
24
28
O
RAMP
5
6
I
REF
15
16
O
RT
17
19
I
SRC
3
4
I
4
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| UC1827J-2 | Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC3827 | Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC2845AJ | OMNIFET II: FULLY AUTOPROTECTED POWER MOSFET |
| UC2845AQTR | OMNIFET II: FULLY AUTOPROTECTED POWER MOSFET |
| UC285-x | FAST TRANSIENT REPONSE 5-A LOW-DROPOUT REGULATOR |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| UC1827J-1 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC1827J-2 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC1827L-1 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC1827-X | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC182DW | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
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