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L4990AD 数据表(PDF) 4 Page - STMicroelectronics

部件名 L4990AD
功能描述  PRIMARY CONTROLLER
PDF  24 Pages
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制造商  STMICROELECTRONICS [STMicroelectronics]
网页  http://www.st.com
标志 STMICROELECTRONICS - STMicroelectronics

L4990AD 数据表(HTML) 4 Page - STMicroelectronics

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FUNCTIONAL DESCRIPTION
The I.C. contains a standard PWM current mode
control section with improved performance with
respect to the UC384X family.
Enhanced features include start-up bias current
reduced to < 270
µA (typ), improved E/A perform-
ance (4MHz B/W, 1.3mA Source Current, high-
slew rate) accurate 1MHz oscillator, and also re-
duced propagation delays in the critical path from
Current Sense to Output.
ADDITIONAL FEATURES
Soft Start (SS)
An external capacitor is charged by an internal
constant current source (20
µA) to generate a SS
signal which clamps the E/A output
The SS pin doubles as a Fault Reset Delay func-
tion as described below.
Current Limit / Reset Delay
An internal high-speed current limit comparator
ELECTRICAL CHARACTERISTICS (continued.)
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
OUTPUT SECTION
VOL
Output Low Voltage
IO = 250mA
1.0
V
VOH
Output High Voltage
IO = 20mA; VCC = 12V
10
10.5
V
IO = 200mA; VCC = 12V
9
10
V
VOUT CLAMP
Output Clamp Voltage
IO = 5mA; VCC = 20V
13
V
Collector Leakage
VCC = 20V VC = 24V
100
200
µA
Fall Time
CO = 1nF
CO = 2.5nF
20
35
60
ns
ns
Rise Time
CO = 1nF
CO = 2.5nF
50
70
100
ns
ns
UVLO Saturation
VCC =0V to VCCON;Isink = 10mA
1.0
V
SUPPLY SECTION
VCCON
Startup voltage
L4990
L4990A
15
7.8
16
8.4
17
9
V
V
VCCOFF
Minimum Operating Voltage
L4990
L4990A
9
7
10
7.6
11
8.2
V
v
Vhys
Voltage After Turn-on Hysteresis
L4990
L4990A
5.5
0.5
6
0.8
V
v
IS
Start Up Current
Before Turn-on at:
VCC =VCCON - 0.5V
100
270
450
µA
Iop
Operating Current
CT = 1nF, RT = 4.42k
Ω,CO =1nF
12
18
mA
Iq
Quiescent Current
(After turn on), Co =0nF
CT = 1nF, RT = 4.42k
Ω,
7.0
10
mA
ISH
Shutdown Current
100
270
450
µA
VZ
Zener Voltage
I8 = 20mA
21
25
30
V
SYNCHRONIZATION SECTION
Master Operation
V1
Clock Amplitude
ISOURCE = 0.8mA
4
V
I1
Clock Source Current
Vclock = 3.5V
7
mA
Slave Operation
V1
Sync Pulse
Low Level
1
V
High Level
3.5
V
I1
Sync Pulse Current
VSYNC = 3.5V
0.8
mA
OVER CURRENT PROTECTION
Vt
Fault Threshold Voltage
1.1
1.2
1.3
V
DISABLE SECTION
Shutdown threshold
2.4
2.5
2.6
V
L4990 - L4990A
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