AP2004
PWM Buck Controller
This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of
this product. No rights under any patent accompany the sale of the product.
Rev. 0.4 Arpr 6, 2004
1/8
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 Description
The AP2004 integrates Pulse-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
1
2
3
8
7
6
5
4
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
Ordering Information
AP2004 X X X
Package Packing
S: SOP-8L
Blank : Tube
A : Taping
Lead Free
Blank : Normal
L : Lead Free Package
N: PDIP-8L
AP2004
PWM Buck Controller
Anachip Corp.
www.anachip.com.tw Rev. 0.4 Apr 6, 2004
2/8
Block Diagram
Bandgap
Reference
OUT
PWM Amplifier
FB
VCC
SCP
CT
Error Amplifier
COMP
UVLO
GND
0.7V
1.5V
+
-
2.5V
Internal use
1.25V
Iss
+
-
VCC
Oscillator
MAX.500KHz
SS
+
+
-
Absolute Maximum Ratings
Symbol Parameter Rating Unit
VCC Supply voltage 28 V
VI Amplifier input voltage 20 V
VO Collector output voltage VCC-1.0V V
ISOURCE Source current 200 mA
ISINK Sink current 200 mA
TOP Operating temperature range -20 to +85 oC
TST Storage temperature range -65 to +150 oC
TLEAD Lead temperature 1.6 mm(1/16 inch) from case for 10 seconds 260 oC
AP2004
PWM Buck Controller
Anachip Corp.
www.anachip.com.tw Rev. 0.4 Apr 6, 2004
3/8
Recommended Operating Conditions
Symbol Parameter Min. Max. Unit
VCC Supply voltage 3.6 27 V
VI Amplifier input voltage 1.05 1.45 V
VO Collector output voltage Vcc-1.5 V
IFB Current into feedback terminal 45 µA
RF Feedback resistor 100 kΩ
CT Timing capacitor 100 6800 pF
FOSC Oscillator frequency 10 300 KHz
TOP Operating free-air temperature -20 85 ºC
Electrical Characteristics (TA=25ºC, VCC=6V, f=200 Khz)
Reference (REF)
Symbol Parameter Conditions Min. Typ. Max. Unit
Comp connect to FB 1.225 1.25 1.275 V
TA = -20ºC ~ 25ºC -0.1 ±1 %
VREF Output voltage change with
temperature TA = 25ºC ~ 85ºC -0.2 ±1 %
Under voltage lockout (UVLO)
Symbol Parameter Conditions Min. Typ. Max. Unit
VUT Upper threshold voltage (VCC) 2.9 V
VLW T Lower threshold voltage (VCC) 2.4 V
VHT Hysteresis (VCC)
IO(REF) = 0.1mA
TA = 25ºC 500 mV
Short-circuit protection (SCP) control
Symbol Parameter Conditions Min. Typ. Max. Unit
VIT Input threshold voltage TA = 25ºC 0.60 0.67 0.75 V
VSTB Standby voltage No pull up 100 130 160 mV
VLT Latched input voltage No pull up 50 100 mV
ISCP Input (source) current VI = 0.7V, TA = 25ºC -10 -15 -20 µA
VCT Comparator threshold voltage
(COMP) 1.5 V
Oscillator (OSC)
Symbol Parameter Conditions Min. Typ. Max. Unit
FOSC Frequency CT =270 pF 200 KHz
Standard deviation of frequency CT =270 pF 10
∆FOSC Frequency change with voltage VCC=3.6V ~ 20V 1
%
AP2004
PWM Buck Controller
Anachip Corp.
www.anachip.com.tw Rev. 0.4 Apr 6, 2004
4/8
Electrical Characteristics (Continued) (TA=25ºC, VCC=6V, f=200 Khz)
Error-amplifier
Symbol Parameter Conditions Min. Typ. Max. Unit
VIO Input offset voltage VO (FB)=1.25V ±6 mV
IIO Input offset current VO (FB)=1.25V ±100 nA
IIB Input bias current VO (FB)=1.25V 160 500 nA
VCM Common-mode input voltage
range VCC=3.6V ~ 20V 1.05 1.45 V
AV Open-loop voltage
amplification RF=200 kΩ 70 80 dB
GBW Unity-gain bandwidth 1.5 MHz
CMRR Common-mode rejection ratio 60 80 dB
VOH Max. output voltage Vref-0.1 V
VOL Min. output voltage 1 V
IOI Output (sink) current (COMP) VID = -0.1V, VO = 1.25V 0.5 1.6 mA
IOO Output (source) current
(COMP) VID = 0.1V, VO = 1.25V -45 -70 µA
Output section
Symbol Parameter Conditions Min. Typ. Max. Unit
ILEAK Leakage current VO = 25V 10 µA
Sink current VIN= 20V 200 mA
IDRV Source current VIN= 20V 200 mA
VSAT Output saturation voltage IO = 10 mA 1.0 1.5 V
ISC Short-circuit output current VO = 6V 120 mA
PWM comparator
Symbol Parameter Conditions Min. Typ. Max. Unit
VT0 CT 0.6 0.7 V
VT100
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
ICCA Average supply current CT = 270pF 6 10 mA
Soft Start
Symbol Parameter Conditions Min. Typ. Max. Unit
VSS Soft-start Voltage 2.3 V
ISS Constant Charge Current 20 µA
AP2004
PWM Buck Controller
Anachip Corp.
www.anachip.com.tw Rev. 0.4 Apr 6, 2004
5/8
Typical Application Circuit
L1
33uH
R1
R2
C3
470uF
Output
Step-Down DC/DC converter
C2
10nF
Optional
Vcc = 12V
P mos
Q1
1
2
3
8
7
6
5
4
OUT
FB
VCC
COMP
GND
SCP
SS
CT
C6 220nF
C5 50nF
C4 270pF
9K
3K
C1
470uF
5A
R3 10K~100K
C4
50nF
Optional
Typical Characteristics
REFERENCE OUTPUT VOLTAGE
v.s.
POWER-SUPPLY VOLTAGE
1.22
1.225
1.23
1.235
1.24
1.245
1.25
1.255
1.26
4 8 12 16 20 24 28
Vcc-Power Supply Voltage (V)
Vref-
Reference
Output Voltage
(V)
AVERAGE SUPPLY CURRENT
v.s.
POWER-SUPPLY VOLTAGE
0
1
2
3
4
5
0 4 8 1216202428
Vcc - Power-Supply Voltgae (V)
Icc-Average
Supply Current
(mA)
AVERAGE SUPPLY CURRENT
v.s.
AMBIENT TEMPERATRUE
2
3
4
5
6
7
-50 -25 0 25 50 75 100
TA - Ambient Temperatrure(℃)
ICC - Average
Supply Current
(mA)
VCT v.s. Frequency
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 100 200 300
Frequency (KHz)
VCT (V)
VCT(min)
VCT(max)
AP2004
PWM Buck Controller
Anachip Corp.
www.anachip.com.tw Rev. 0.4 Apr 6, 2004
6/8
Typical Characteristics (Continued)
OSCILLATOR FREQUENCY
v.s.
TIMING CAPACITANCE
0
50
100
150
200
250
300
350
100 600 1100 1600 2100 2600 3100 3600 4100 4600 5100 5600 6100 6600
CT-Timing Capacitor (pF)
fosc - Frequency
(KHz)
SCP TIME-OUT PERIOD
v.s.
SCP CAPACITANCE
0
5
10
15
20
25
30
35
45 90 135 180 225 270 315 360 405 450 495
Cscp - SCP Capacitance (nF)
tscp-SCP Time-out
Period (ms)
SOFT-START TIME (Ts)
v.s.
SOFT-START CAPACITOR (Css)
0
5
10
15
20
25
30
25 50 75 100 125 150 175 200
Css (nF)
Ts (mS)
Marking Information
(Top View)
PDIP/SOP
AC
AP2004
YY WW X X
Logo
Part No.
ID code
Year: "01" =2001
"02" =2002
Xth week: 01~52
~
5
8
41
Blank: normal
L: Lead Free Package
AP2004
PWM Buck Controller
Anachip Corp.
www.anachip.com.tw Rev. 0.4 Apr 6, 2004
7/8
Package Information
(1) PDIP-8L (Plastic Dual-in-line Package )
E1
D
7(4X)
AL
A2A1
B2
B1
B
e
S
15 (4X)
E
C
eB
E-PIN O0.118 inch
PIN #1 INDENT O0.025 DEEP 0.006-0.008 inch
Dimensions in millimeters Dimensions in inches
Symbol Min. Nom. Max. Min. Nom. Max.
A - - 5.33 - - 0.210
A1 0.38 - - 0.015 - -
A2 3.1 3.30 3.5 0.122 0.130 0.138
B 0.36 0.46 0.56 0.014 0.018 0.022
B1 1.4 1.52 1.65 0.055 0.060 0.065
B2 0.81 0.99 1.14 0.032 0.039 0.045
C 0.20 0.25 0.36 0.008 0.010 0.014
D 9.02 9.27 9.53 0.355 0.365 0.375
E 7.62 7.94 8.26 0.300 0.313 0.325
E1 6.15 6.35 6.55 0.242 0.250 0.258
e - 2.54 - - 0.100 -
L 2.92 3.3 3.81 0.115 0.130 0.150
eB 8.38 8.89 9.40 0.330 0.350 0.370
S 0.71 0.84 0.97 0.028 0.033 0.038
AP2004
PWM Buck Controller
Anachip Corp.
www.anachip.com.tw Rev. 0.4 Apr 6, 2004
8/8
Package Information (Continued)
(2) SOP- 8L(JEDEC Small Outline Package)
VIEW "A"
L
C
VIEW "A"
H
E
A
A2
A1
B
e
D
7(4X) 0.015x45 7(4X)
y
Dimensions In Millimeters Dimensions In Inches
Symbol Min. Nom. Max. Min. Nom. Max.
A 1.40 1.60 1.75 0.055 0.063 0.069
A1 0.10 - 0.25 0.040 - 0.100
A2 1.30 1.45 1.50 0.051 0.057 0.059
B 0.33 0.41 0.51 0.013 0.016 0.020
C 0.19 0.20 0.25 0.0075 0.008 0.010
D 4.80 5.05 5.30 0.189 0.199 0.209
E 3.70 3.90 4.10 0.146 0.154 0.161
e - 1.27 - - 0.050 -
H 5.79 5.99 6.20 0.228 0.236 0.244
L 0.38 0.71 1.27 0.015 0.028 0.050
y - - 0.10 - - 0.004
θ 0O - 8O 0
O - 8O
