PWM Buck Controller
Features
- PWM Buck Control Circuitry
- Operating voltage can be up to 27V
- Under voltage Lockout (UVLO) Protection - Short Circuit Protection (SCP) - Soft-start circuit
- Variable Oscillator Frequency -- 300Khz Max - 1.25V voltage reference Output - 8-pin PDIP and SOP packages
Applications
- Backlight inverter - LCD Monitor
- XDROM, XDSL Product
- DC/DC converters in computers, etc.
General Descriptionclothes
The AP2004 integrates Pul-Width-Modulation (PWM) control circuit into a single chip, mainly designs for power-supply regulator. All the functions include an on-chip 1.25V reference output, an error amplifier, an adjustable oscillator, a soft-start, UVLO, SCP circuitry, and a push-pull output circuit. Switching frequency is adjustable by trimming CT. During low VCC situation, the UVLO makes sure that the outputs are off until the internal circuit operates normally.
Pin Assignment
OUT GND SCP
SS FB
VCC CT COMP
( Top View )
PDIP/SOP
Pin Descriptions
Name
Description
CT Timing
Capacitor FB Voltage Feedback SS Soft-Start. COMP
Feedback Loop Compensation
OUT PWM Output
GND Ground VCC Supply Voltage SCP Short Circuit Protection
长春雅思培训Ordering Information
S: SOP-8L
A : Taping
L : Lead Free Package
ebitPWM Buck Controller
Block Diagram
OUT
FB
VCC
SCP CT
COMP
GND
SS
Absolute Maximum Ratings十二月英语
Symbol Parameter
Rating Unit V CC Supply voltage 28 V V I Amplifier input voltage 20 V V O Collector output voltage V CC -1.0V
V
I SOURCE Source current 200 mA I SINK Sink current
200 mA T OP Operating temperature range -20 to +85 o C T ST Storage temperature range
-65 to +150
o C T LEAD Lead temperature 1.6 mm(1/16 inch) from ca for 10 conds
260
o
C
PWM Buck Controller
Recommended Operating Conditions
大昭寺简介
Symbol
Parameter提问方式
Min. Max. Unit V CC Supply voltage 3.6 27
V V I Amplifier input voltage 1.05 1.45
V V O Collector output voltage Vcc-1.5 V
法律研究生考试科目I FB
Current into feedback terminal
45 µA R F Feedback resistor 100 k Ω C T Timing capacitor 100 6800smart意思
pF F OSC Oscillator frequency 10 300 KHz T OP
Operating free-air temperature
-20
85
ºC
Electrical Characteristics (T A
=25ºC, V
CC
=6V, f=200 Khz)
Reference (REF) Symbol Parameter Conditions Min.Typ. Max.Unit
Comp connect to FB 1.225 1.25 1.275V
T A = -20ºC ~ 25ºC -0.1 ±1 % V REF Output voltage change with
temperature T A = 25ºC ~ 85ºC -0.2 ±1 %
Under voltage lockout (UVLO) Symbol Parameter Conditions Min.Typ. Max.Unit V UT Upper threshold voltage (V CC ) 2.9 V
V LWT Lower threshold voltage (V CC ) 2.4 V
V HT Hysteresis (V CC ) I O(REF) = 0.1mA
T A = 25ºC
500 mV Short-circuit protection (SCP) control Symbol Parameter Conditions Min.Typ. Max.Unit V IT Input threshold voltage T A = 25ºC 0.600.67 0.75V V STB Standby voltage No pull up 100 130 160 mV V LT Latched input voltage No pull up 50 100 mV I SCP Input (source) current V I = 0.7V, T A = 25ºC -10 -15 -20 µA
V CT Comparator threshold voltage
(COMP)
1.5 V
Oscillator (OSC) Symbol Parameter Conditions Min.Typ. Max.Unit F OSC Frequency C T =270 pF 200 KHz
Standard deviation of frequency C T =270 pF 10
∆F OSC Frequency change with voltage V CC =
3.6V ~ 20V 1
%
PWM Buck Controller
Electrical Characteristics (Continued) (T A
=25ºC, V
CC
=6V, f=200 Khz)
Error-amplifier
Symbol Parameter Conditions
Min.Typ. Max. Unit V IO Input offt voltage V O (FB)=1.25V ±6 mV I IO Input offt current V O (FB)=1.25V ±100 nA I IB Input bias current
V O (FB)=1.25V 160 500 nA V CM
Common-mode input voltage
range
V CC =3.6V ~ 20V
1.05
1.45
V
AV
Open-loop voltage
amplification
R F =200 k Ω 70 80 dB
GBW Unity-gain bandwidth
1.5 MHz CMRR Common-mode rejection ratio 60 80 dB V OH Max. output voltage V ref -0.1 V
V OL Min. output voltage
1 V I OI Output (sink) current (COMP)
V ID = -0.1V, V O = 1.25V 0.5 1.6 mA I OO
Output (source) current
(COMP)
V ID = 0.1V, V O = 1.25V
-45 -70 µA Output ction
Symbol Parameter
Conditions Min.Typ. Max. Unit I LEAK Leakage current V O = 25V 10 µA Sink current V IN = 20V 200 mA I DRV Source current
V IN = 20V 200 mA V SAT
Output saturation voltage
I O = 10 mA 1.0 1.5 V I SC Short-circuit output current
V O = 6V
120 mA PWM comparator
Symbol Parameter
Conditions
Min.
Typ.
Max.
Unit
V T0 CT 0.6 0.7 V V T100 Input threshold voltage at f =
10 KHz (COMP) Maximum duty cycle 1.2 1.3 V Total device
Symbol
Parameter
Conditions
Min.Typ. Max. Unit I CCA Average supply current C T = 270pF
6 10 mA Soft Start
Symbol Parameter Conditions
昌平龙德广场Min.Typ. Max. Unit V SS Soft-start Voltage 2.3 V
I SS
Constant Charge Current
20
µA
PWM Buck Controller
不给糖就捣蛋的英文
Typical Application Circuit
C3Step-Down DC/DC converter
Typical Characteristics
