Download Preliminary Datasheet General Description

Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
General Description
Features
The AP3512E is a 500kHz fixed frequency, current
mode, PWM synchronous buck (step-down) DC-DC
converter, capable of driving a 2A load with high
efficiency, excellent line and load regulation. The
AP3512E exhibits high efficiency at light load. The
device integrates N-channel power MOSFET switch
with low on-resistance. Current mode control
provides fast transient response and cycle-by-cycle
current limit.
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The AP3512E employs complete protection to ensure
system security, including output Over Voltage
Protection, input Under Voltage Lock Out,
programmable
Soft-start,
Over
Temperature
Protection and hiccup mode Short Circuit Protection.
Input Voltage Range: 4.5V to 18V
Fixed 500kHz Frequency
High Efficiency at Light Load
Output Current: 2A
Current Mode Control
Built-in Over Current Protection
Built-in Thermal Shutdown Function
Built-in UVLO Function
Built-in Over Voltage Protection
Programmable Soft-start
Hiccup Mode SCP
Applications
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This IC is available in SOIC-8 and PSOP-8 packages.
SOIC-8
Monitor
TV
STB
Datacom
PSOP-8
Figure 1. Package Types of AP3512E
Dec. 2012
Rev. 1. 1
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Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
Pin Configuration
M Package
(SOIC-8)
MP Package
(PSOP-8)
BS
1
8
SS
BS
1
IN
2
7
EN
IN
2
SW
3
6
COMP
SW
GND
4
5
FB
GND
8
SS
7
EN
3
6
COMP
4
5
FB
EP
Figure 2. Pin Configuration of AP3512E (Top View)
Pin Description
Pin Number
Pin Name
1
BS
2
IN
3
SW
4
GND
5
FB
6
COMP
7
EN
8
SS
EP
Dec. 2012
Function
Bootstrap pin. A bootstrap capacitor is connected between the
BS pin and SW pin. The voltage across the bootstrap
capacitor drives the internal high-side NMOS switch.
Supply input pin. A capacitor should be connected between
the IN pin and GND pin to keep the DC input voltage
constant.
Power switch output pin. This pin is connected to the inductor
and bootstrap capacitor.
Ground pin
Feedback pin. This pin is connected to an external resistor
divider to program the system output voltage. When the FB
pin voltage exceeds 1.1V, the over voltage protection is
triggered. When the FB pin voltage is below 0.3V, the
oscillator frequency is lowered to realize short circuit
protection.
Compensation pin. This pin is the output of the
transconductance error amplifier and the input to the current
comparator. This pin is used to compensate the control loop.
Connect a series RC network from this pin to GND pin. In
some cases, an additional capacitor from this pin to GND pin
is required.
Enable Input. EN is a digital input that turns the regulator on
or off. Drive EN high to turn on the regulator, drive it low to
turn off. Pull up with 100kΩ resistor for automatic startup.
Soft-start control input pin. SS controls the soft start period.
Connect a capacitor from SS to GND to set the soft-start
period. A 0.1µF capacitor sets the soft-start period to 15ms.
To disable the soft-start feature, leave SS unconnected.
Exposed pad. It should be connected to GND in PCB layout
Rev. 1. 1
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Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
Functional Block Diagram
Figure 3. Functional Block Diagram of AP3512E
Ordering Information
AP3512E
-
Circuit Type
G1: Green
Package
M: SOIC-8
MP: PSOP-8
Blank: Tube
TR: Tape & Reel
Package
Temperature
Range
SOIC-8
-40 to 85°C
PSOP-8
-40 to 85°C
Part Number
Marking ID
Packing
Type
AP3512EM-G1
3512EM-G1
Tube
AP3512EMTR-G1
3512EM-G1
Tape & Reel
AP3512EMPTR-G1
3512EMP-G1
Tape & Reel
BCD Semiconductor's Pb-free products, as designated with "G1" suffix in the part number, are RoHS compliant
and green.
Dec. 2012
Rev. 1. 1
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Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
Absolute Maximum Ratings (Note 1)
Parameter
Symbol
Value
Unit
IN Pin Voltage
VIN
-0.3 to 20
V
EN Pin Voltage
VEN
-0.3 to VIN
V
SW Pin Voltage
VSW
21
V
BS Pin Voltage
VBS
-0.3 to VSW+6
V
FB Pin Voltage
VFB
-0.3 to 6
V
VCOMP
-0.3 to 6
V
SS Pin Voltage
VSS
-0.3 to 6
V
Operating Junction Temperature
TJ
150
ºC
COMP Pin Voltage
Storage Temperature
Lead Temperature
(Soldering, 10sec)
Thermal Resistance
(Junction to Ambient)
TSTG
-65 to 150
ºC
TLEAD
260
ºC
ESD (Human Body Model)
VHBM
2000
V
ESD (Machine Model)
VMM
200
V
SOIC-8
PSOP-8
θJA
105
60
ºC/W
Note 1: Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to
the device. These are stress ratings only, and functional operation of the device at these or any other conditions
beyond those indicated under “Recommended Operating Conditions” is not implied. Exposure to “Absolute
Maximum Ratings” for extended periods may affect device reliability.
Recommended Operating Conditions
Parameter
Symbol
Min
Max
Unit
Input Voltage
VIN
4.5
18
V
Operating Ambient Temperature
TA
-40
85
ºC
Dec. 2012
Rev. 1. 1
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Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
Electrical Characteristics
VIN=VEN=12V, VOUT=3.3V, TA=25ºC, unless otherwise specified.
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
18
V
SUPPLY VOLTAGE (IN PIN)
Input Voltage
VIN
4.5
VFB=1V,
VEN=3.3V
1.2
1.4
mA
ISHDN
VEN=0V
0.1
1.0
µA
Input UVLO Threshold
VUVLO
VIN Rising
4.0
4.25
V
Input UVLO Hysteresis
VHYS
Quiescent Current
IQ
Shutdown Supply Current
UNDER VOLTAGE LOCKOUT
3.65
0.2
V
ENABLE (EN PIN)
EN Shutdown Threshold Voltage
EN Shutdown Threshold Voltage
Hysteresis (Note 2)
EN Lockout Threshold Voltage
1.1
1.5
2
350
2.2
EN Lockout Hysteresis
2.5
V
mV
2.7
210
V
mV
VOLTAGE REFERENCE (FB PIN)
Feedback Voltage
VFB
Feedback Over Voltage Threshold
Feedback Bias Current
0.907
VFBOV
IFB
0.925
0.943
1.1
VFB=1V
-0.1
V
V
0.1
µA
MOSFET
High-side Switch On-resistance
(Note 3)
Low-side Switch On-resistance
(Note 3)
RDSONH
ISW=0.2A&0.7A
100
mΩ
RDSONL
ISW=-0.2A&-0.7A
100
mΩ
CURRENT LIMIT
High-side
Switch
Leakage
Current
High-side Switch Current Limit
ILEAKH
VIN=18V, VEN=0V,
VSW=0V
0.1
Low-side Switch Current Limit
ILIMH
ILIML
4.3
From drain
source
to
10
μA
5.6
A
50
mA
SWITCHING REGULATOR
Oscillator Frequency
Short
Circuit
Frequency
Dec. 2012
fOSC1
Oscillator
410
500
180
fOSC2
Rev. 1. 1
590
kHz
kHz
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Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
Electrical Characteristics (Continued)
VIN=VEN=12V, VOUT=3.3V, TA=25ºC, unless otherwise specified.
Parameter
Symbol
Conditions
Min
Typ
Max
Max. Duty Cycle
DMAX
VFB=0.85V
Min. Duty Cycle
DMIN
VFB=1V
ERROR AMPLIFIER
Error Amplifier Voltage Gain
(Note 2)
Error Amplifier Transconductance
AEA
400
V/V
GEA
800
μA/V
GCS
5.2
A/V
Thermal Shutdown (Note 2)
TOTSD
160
ºC
Thermal
(Note 2)
THYS
30
ºC
15
ms
5
μA
COMP
to
Current
Transconductance
Sense
90
Unit
%
0
%
THERMAL SHUTDOWN
Shutdown
Hysteresis
SOFT START (SS PIN)
Soft-start Time (Note 2)
tSS
CSS=0.1μF
Soft-start Current
Note 2: Not tested, guaranteed by design.
Note 3: RDSON=
Dec. 2012
VSW1 - VSW2
I SW1 - I SW2
Rev. 1. 1
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Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
Typical Performance Characteristics
VIN=12V, VOUT=3.3V, L=4.7µH, TA=25°C, unless otherwise noted.
1.30
100
1.25
90
1.20
Quiescent Current (mA)
Efficiency (%)
80
70
60
50
VIN=12V
VOUT=3.3V, L=4.7μH
VOUT=5.0V, L=6.8μH
40
30
1.15
1.10
1.05
1.00
0.95
0.90
0.85
20
0.80
10
0.01
0.1
1
-50
-25
0
25
50
75
100
125
150
o
Temperature ( C)
Load Current (A)
Figure 4. Efficiency vs. Load Current
Figure 5. Quiescent Current vs. Temperature
1.2
Feedback Voltage (V)
1.1
VSW
(10V/div)
1.0
VOUT-AC
(20mV/div)
0.9
IL
(1A/div)
0.8
0.7
0.6
-50
-25
0
25
50
75
100
125
150
Time(1µs/div)
o
Temperature ( C)
Figure 6. Feedback Voltage vs. Temperature
Dec. 2012
Figure 7. Output Ripple (IOUT=2A)
Rev. 1. 1
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Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
Typical Performance Characteristics (Continued)
VIN=12V, VOUT=3.3V, L=4.7µH, TA=25°C, unless otherwise noted.
VOUT-AC
(100mV/div)
VOUT-AC
(100mV/div)
IOUT
(1A/div)
IOUT
(1A/div)
Time(100µs/div)
Time(100µs/div)
Figure 8. Load Transient Response (IOUT=1A to 2A)
Figure 9. Load Transient Response (IOUT=0.2A to 2A)
VIN
(10V/div)
VIN
(10V/div)
VOUT
(2V/div)
VOUT
(2V/div)
IL
(1A/div)
IL
(1A/div)
Dec. 2012
Time(3.20ms/div)
Time(3.20ms/div)
Figure 10. Power On from VIN (IOUT=2A)
Figure 11. Power Off from VIN (IOUT=2A)
Rev. 1. 1
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Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
Typical Performance Characteristics (Continued)
VIN=12V, VOUT=3.3V, L=4.7µH, TA=25°C, unless otherwise noted.
VEN
(2V/div)
VEN
(2V/div)
VOUT
(2V/div)
VOUT
(2V/div)
IL
(1A/div)
IL
(1A/div)
Time(3.20ms/div)
Time(3.20ms/div)
Figure 12. Power On from EN (IOUT=2A)
Figure 13. Power Off from EN (IOUT=2A)
VSS
(1V/div)
VSS
(1V/div)
VOUT
(2V/div)
VSW
(10V/div)
VOUT
(2V/div)
VSW
(10V/div)
IL
(2A/div)
IL
(2A/div)
Time(64ms/div)
Time(64ms/div)
Figure 14. Short Circuit Protection (IOUT=2A)
Dec. 2012
Figure 15. Short Circuit Protection Recovery (IOUT=2A)
Rev. 1. 1
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Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
Typical Application
Figure 16. Typical Application Circuit of AP3512E
Dec. 2012
Rev. 1. 1
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Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
Mechanical Dimensions
SOIC-8
4.700(0.185)
5.100(0.201)
7°
Unit: mm(inch)
0.320(0.013)
1.350(0.053)
1.750(0.069)
8°
8°
7°
0.675(0.027)
0.725(0.029)
D
5.800(0.228)
1.270(0.050)
6.200(0.244)
TYP
D
20:1
0.800(0.031)
0.300(0.012)
R0.150(0.006)
0.100(0.004)
0.200(0.008)
0°
8°
1.000(0.039)
3.800(0.150)
4.000(0.157)
0.330(0.013)
0.190(0.007)
0.250(0.010)
1°
5°
0.510(0.020)
0.900(0.035)
R0.150(0.006)
0.450(0.017)
0.800(0.031)
Note: Eject hole, oriented hole and mold mark is optional.
Dec. 2012
Rev. 1. 1
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Preliminary Datasheet
18V, 2A Synchronous DC-DC Buck Converter
AP3512E
Mechanical Dimensions (Continued)
Unit: mm(inch)
3.202(0.126)
3.402(0.134)
PSOP-8
Dec. 2012
Rev. 1. 1
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