AP3436A [BCDSEMI]
3A, 1.25MHz High Performance Synchronous Buck Converter; 3A ， 1.25MHz的高性能同步降压转换器
| 型号： | AP3436A |
| 厂家： | 
BCD SEMICONDUCTOR MANUFACTURING LIMITED |
| 描述： | 3A, 1.25MHz High Performance Synchronous Buck Converter |
| 文件： | 总15页 (文件大小：532K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Features
General Description
•
•
•
•
Analog Power Input VCC Range: 3.0V to 5.5V
Power Input VIN Range: 1.3V to 5.5V
0.6V Reference Voltage with ±1.5% Precision
2 MOSFETs (Typ 50mΩ) for High Efficiency at
3A Loads
High Efficiency: Up to 95%
Output Current: 3A
Current Mode Control
Built-in Soft Start Function
UV and OV Power Good Output
Built-in UV and OV Protection Function
Built-in Over Current Protection
Built-in Thermal Shutdown Function
Thermally Enhanced 3mm×3mm DFN Package
The AP3436/A is a step-down DC-DC converter
with integrated power stage capable of driving up to
3A continuous output current. It integrates 2
N-channel power MOSFETs with low on-resistance.
Current mode control provides fast transient
response and cycle-by-cycle current limit.
•
•
•
•
•
•
•
•
•
For AP3436, the regulator adopts current-mode in
forced pulse-width modulation (PWM) mode with
1.25MHz switching frequency internally, which
allows small-sized components, such as capacitors
and inductors. This feature greatly simplifies the
design of switch-mode power supplies. Under PWM
mode, the device remains at the fixed PWM
operation (typical at 1.25MHz), regardless of if the
load current is high or low.
For AP3436A, the regulator operates in either fixed
PWM mode or a pulse-skipping modulation (PSM)
mode depending on the different load conditions.
The device can operate at typical 1.25MHz fixed
switching frequency under heavy load condition. At
light load, the regulator enters a PSM mode to
minimize the switching loss by reducing the
switching frequency.
Applications
•
•
•
Desktop & Notebook
Low Voltage, High Density Power System
Consumer Application Such as Set Top Box,
LCD Display and CPE Equipment
The AP3436/A provides EN function. Pulling this
pin high statically enables the device while pulling
the pin low statically for longer than 10µs will shut it
down.
Under Voltage Lockout is internally set at 2.75V for
VCC detection. The output voltage startup ramp is
controlled by the soft start. An open drain power
good signal indicates the output is within 75% to
125% of its nominal voltage.
The AP3436/A is available in DFN-3×3-10 package.
DFN-3×3-10
Figure 1. Package Type of AP3436/A
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
1
Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Pin Configuration
DN Package
(DFN-3×3-10)
Pin 1 Mark
1
2
3
10
9
8
7
6
4
5
Figure 2. Pin Configuration of AP3436/A (Top View)
Pin Description
Pin Number
Pin Name
Function
Voltage Feedback Input. Connect to VOUT through a voltage
divider to set the output voltage
1
FB
2
3
VCC
VIN
Analog Power Input
Power Input
4, 5
6, 7
8
GND
SW
Ground. Must be Connected to GND on PCB
Power Switch Output
BOOT
PGOOD
EN
High Side Switch Driver Supply
Open Drain Power Good Output
Enable
9
10
Thermal Connection to the PCB. Must be connected to GND
on PCB
11
Exposed Pad
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
2
Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Functional Block Diagram
EN
PGOOD
VCC
2
VIN
3
9
10
Thermal
Shutdown
UVLO
75%
Logic
Boot
Charge
Shutdown
Logic
EN
125%
8
BOOT
Voltage
Reference
Boot
UVLO
1
FB
EA
Logic and
PWM Latch
PWM
6,7
SW
Slope
Compensation
+
Soft Start
Current
Sense
Current Limit and
Short Protection
Oscillator
4,5
GND
4,5
GND
Figure 3. Functional Block Diagram of AP3436/A
Ordering Information
AP3436
-
G1: Green
Circuit Type
TR: Tape & Reel
Package
Blank: AP3436
A: AP3436A
DN: DFN-3×3-10
Temperature
Package
Range
Function
PWM
Part Number
AP3436DNTR-G1
AP3436ADNTR-G1
Marking ID
BDB
Packing Type
DFN-3×3-10
-40 to 85°C
Tape & Reel
PWM/PSM
BDF
BCD Semiconductor's Pb-free products, as designated with "G1" in the part number, are RoHS compliant and
green.
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
3
Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Absolute Maximum Ratings (Note 1)
Parameter
Symbol
VCC, VIN
VEN
Value
-0.3 to 6
-0.3 to 6
Unit
V
VCC, VIN Pin Voltage
EN Pin Voltage
V
-0.3 to
VIN+0.3
SW Pin Voltage
VSW
V
SW Pin Transient Voltage (<50ns)
FB Pin Voltage
VSW_TRANSIENT
VFB
-5 to VIN+5
-0.3 to 6
-0.3 to 6
0 to 6
V
V
PGOOD Pin Voltage
VPGD
V
BOOT to SW Voltage
VBOOT_SW
θJA
V
Thermal Resistance (Junction to Ambient, Simulation)
Operating Junction Temperature
Storage Temperature
33
ºC/W
ºC
ºC
ºC
V
TJ
-40 to 150
-65 to 150
260
TSTG
Lead Temperature (Soldering, 10sec)
ESD (Human Body Model)
ESD (Machine Model)
TLEAD
VHBM
VMM
2000
V
200
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
VCC
Min
3.0
1.3
3
Max
5.5
Unit
V
Analog Input Voltage
Power Input Voltage
Maximum Output Current
Output Voltage
VIN
5.5
V
IOUT(MAX)
VOUT
TA
A
0.8
-40
VIN
85
V
Operating Ambient Temperature
ºC
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
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Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Electrical Characteristics
VCC=5V, VIN=5V, TA=25°C, unless otherwise specified.
Parameter
Symbol
Conditions
Min Typ Max Unit
SUPPLY VOLTAGE (VCC, VIN PIN)
Analog
Voltage
Power
Input
VCC
VIN
IQ
3.0
1.3
5.5
5.5
V
V
Power Input Voltage
Quiescent Current
VFB=1.5V, VCC=5V,
VIN=5V
400
µA
VEN=0V, 3.0V≤VCC≤5.5V,
1.3V≤VIN≤5.5V
ISHDN
1
µA
Shutdown Supply Current
POWER ON RESET
Internal Under Voltage
Lockout Threshold for VCC
Internal Under Voltage
Hysteresis for VCC
VUVLO
2.75
150
2.85
V
VHYS_VCC
mV
VOLTAGE REFERENCE (FB PIN)
VFB
INTERNAL PWM FREQUENCY
3.0V≤VCC≤5.5V
3.0V≤VCC≤5.5V
0.591 0.600 0.609
V
Voltage Reference
1.0
1.25
1.5
MHz
f
PWM Frequency
MOSFET SPEC
VBOOT_SW=5.0V
VBOOT_SW=3.0V
VCC=5.0V
50
70
50
70
100
140
100
140
mΩ
mΩ
mΩ
mΩ
High
On-resistance
Side
Switch
Switch
RON_H
Low
On-resistance
Side
RON_L
VCC=3.0V
CURRENT LIMIT
ILIMIT
4.8
7.6
A
Current Limit Threshold
THERMAL SHUTDOWN
Thermal Shutdown
TTSD
160
20
°C
°C
Hysteresis
BOOT SPEC (BOOT PIN)
BOOT Charge Resistor
BOOT to SW UVLO
RBOOT
VCC=5.0V
VCC=3.0V
16
Ω
2.2
V
SOFT START
Soft Start Time
tSS
0.8
2
ms
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
5
Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Electrical Characteristics (Continued)
VCC=5V, VIN=5V, TA=25°C, unless otherwise specified.
Parameter
Symbol
Conditions
Min
Typ
Max Unit
ENABLE (EN PIN)
VEN_L
VEN_H
0.8
V
V
EN Pin Threshold
1.6
POWER GOOD (PGOOD PIN)
VFB falling (Fault)
VFB rising (Good)
VFB rising (Fault)
VFB falling (Good)
70
77
75
82
Feedback Threshold
VFBTH
%VREF
125
118
130
123
Delay
Time
for
PGOOD from High to
Low
tPG_DLY
30
µs
Internal Power Good
Pull Low Resistance
RPG
150
Ω
Ω
External
Pull-up
RPG_UP
3000
Resistance Range
SYSTEM PERFORMANCE
Output Under Voltage
Protection Threshold
Delay Time for UVP
Triggered
Output Over Voltage
Protection Threshold
Delay Time for OVP
Triggered
0.5×
VOUT
VUVP
tUVP
VOVP
tOVP
VIN=1.3 to 5.5V
VIN=1.5 to 5V
VIN=1.3 to 5.5V
VIN=1.5 to 5V
V
µs
V
65
65
1.5×
VOUT
µs
A
VIN=1.5 to 5V,
VOUT=1.0V
Output Current
IOUT
3
Output Voltage Line
Regulation
Output Voltage Load
Regulation
VIN=1.5 to 5V,
IOUT=100mA
%×
VOUT/V
%×
0.4
0.3
I
OUT=0A to 3A
V
OUT/A
VIN=5V, VOUT=1.0V,
dI/dt=400mA/µs
VCC=5V, VIN=5V,
IOUT=3A, VOUT=1.2V
Output Voltage Load
Transient
%×
OUT/A
VTRAN
±2.5
80
V
Efficiency
η
%
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
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Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Typical Performance Characteristics
100
90
80
70
60
50
40
30
20
10
0
0.610
0.608
0.606
0.604
0.602
0.600
0.598
0.596
0.594
0.592
0.590
AP3436
VIN=VCC=5.0V
VOUT=1.0V
VIN=VCC=VEN
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00
3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50
Output Current (A)
Input Voltage(V)
Figure 4. Efficiency vs. Output Current
Figure 5. Reference Voltage vs. Input Voltage
1.50
0.64
0.63
0.62
0.61
0.60
0.59
0.58
0.57
0.56
1.45
1.40
1.35
1.30
1.25
1.20
1.15
1.10
1.05
1.00
VIN=VCC=5.0V
VCC=VIN=VEN
3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50
-40
-20
0
20
40
60
80
100
120
140
Temperature (oC)
Input Voltage (V)
Figure 6. Reference Voltage vs. Temperature
Figure 7. PWM Frequency vs. Input Voltage
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
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Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Typical Performance Characteristics (Continued)
10.0
9.5
9.0
8.5
8.0
7.5
7.0
6.5
6.0
5.5
5.0
1.50
1.45
1.40
1.35
1.30
1.25
1.20
1.15
1.10
1.05
1.00
VIN=VCC=5.0V
VIN=VCC=VEN
3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50
-40
-20
0
20
40
60
80
100
120
140
Temperature (oC)
Input Voltage (V)
Figure 8. PWM Frequency vs. Temperature
Figure 9. Current Limit vs. Input Voltage
9.00
0.4
8.75
8.50
8.25
8.00
7.75
7.50
7.25
7.00
6.75
6.50
6.25
6.00
0.3
0.2
VIN=VCC=5.0V
0.1
0.0
-0.1
-0.2
-0.3
-0.4
VIN= VCC= VEN
VOUT = 1.0V
3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50
-40
-20
0
20
40
60
80
100
120
140
Temperature (oC)
Input Voltage (V)
Figure 10. Current Limit vs. Temperature
Figure 11. Line Regulation vs. Input Voltage
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
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Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Typical Performance Characteristics (Continued)
1.0
0.8
0.6
VIN
0.4
2V/div
VOUT
500mV/div
0.2
0.0
-0.2
-0.4
IL
1A/div
-0.6
VIN=VCC=VEN=5.0V
-0.8
VOUT=1.0V
-1.0
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00
Time 400µs/div
Output Current (A)
Figure 12. Load Regulation vs. Output Current
Figure 13. Power on Waveform
(VIN=VCC=5V, VOUT=1V, IOUT=3A)
VIN
VCC/IN
2V/div
2V/div
VEN
1V/div
VOUT
1V/div
VOUT
500mV/div
IL
2A/div
IL
1A/div
Time 20ms/div
Time 1ms/div
Figure 14. Power off Waveform
(VIN=VCC=5V, VOUT=1V, IOUT=3A)
Figure 15. Enable Waveform
(VIN=VCC=5V, VOUT=1V, IOUT=3A)
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
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Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Typical Performance Characteristics (Continued)
VCC/IN
2V/div
VEN
1V/div
VOUT_AC
20mV/div
VOUT
500mV/div
IL
1A/div
IOUT
1A/div
Time 200µs/div
Time 200µs/div
Figure 16. Disable Waveform
(VIN=VCC=5V, VOUT=1V, IOUT=3A)
Figure 17. Load Transient Response
(VIN=VCC=5V, VOUT=1V, IOUT=0 to 3A)
VOUT_AC
20mV/div
IOUT
1A/div
Time 200µs/div
Figure 18. Load Transient Response
(VIN=VCC=3.3V, VOUT=1V, IOUT=0 to 3A)
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
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Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Typical Application
VCC
V
IN
VOUT
CVCC
C
IN
RPG
9
3
8
PGOOD
EN
VIN
L1
CBOOT
10
2
BOOT
6
7
4
5
11
COUT
SW
SW
GND
GND
EP
VCC
FB
1
RFB2
RFB1
Note 2: When using a single power supply for VCC and VIN, a 4.7Ω resistor should be placed between them for
noise isolation.
Figure 19. Typical Application Circuit of AP3436/A
Table 1. Component Guide
Component
CVCC
Value
1
Unit
µF
Component
CIN
Value
44
Unit
µF
RPG
10
CBOOT
L1
0.1
kΩ
kΩ
kΩ
µF
RFB2
TBD
TBD
1.5
µH
µF
RFB1
COUT
88
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
11
Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Application Information
R1× 0.6
R2 =
VOUT − 0.6
1. Overview
The AP3436/A is a 3A synchronous buck (step-down)
converter with two integrated N-channel MOSFETs.
VOUT
AP3436/A
For AP3436, the regulator operates in PWM mode
with 1.25MHz switching frequency internally,
R1
FB
regardless of if the load current is high or low. For
-
+
+
AP3436A, when the load is very light, the regulator
automatically operates in the PSM mode to minimize
the switching loss, thus achieving high efficiency at
light load. When the load increases, the regulator
automatically switches over to a current-mode PWM
operating at nominal 1.25MHz switching frequency.
0.6V
VSS
R2
Figure 20. Voltage Divider Circuit
2. Power On Reset
A Power On Reset (POR) circuitry continuously
monitors the supply voltage at VCC pin. Once the
rising POR threshold is exceeded, the AP3436/A sets
itself to active state and is ready to accept chip enable
command. The rising POR threshold is typically
2.75V.
6. Short Circuit Protection (SCP)
The AP3436/A has Over Current Protection (OCP)
and Under Voltage Protection (UVP) functions.
6.1 OCP Function
The high side switch current is detected during each
cycle. During SCP conditions, the output voltage is
pulled down and the switch current is increased.
Once the increased high side switching current is
detected to trigger the current limit of high side
switch, the high side switch will be immediately
turned off and will not be turned on again until the
next switching cycle. When over current condition is
removed, the AP3436/A will recover back to normal
operation again.
3. Soft Start
A built-in soft-start is used to prevent surge current
from power supply input VIN during turn on
(Referring to the Functional Block Diagram). The
error amplifier is a three-input device. Reference
voltage VREF or the internal soft-start voltage VSS
whichever is smaller dominates the behavior of the
non-inverting inputs of the error amplifier. VSS
internally ramps up to 0.6V after the soft-start cycle
is initiated. The ramp is created digitally, so the
output voltage will follow the VSS signal and ramps
up smoothly to its target level.
6.2 UVP Function
The FB voltage is also monitored for Under Voltage
Protection. The UV threshold is set at 0.2V. The
under voltage protection has 65µs triggered delay.
When UVP is triggered, both high side and low side
are shutdown immediately. The UVP is a latched
function, reset power supply or EN pin to restart
AP3436/A again.
4. EN Function
The AP3436/A provides Enable Function. Pulling
this pin higher than 1.6V statically enables the
AP3436/A while pulling the pin lower than 0.8V
statically for longer than 10µs will shutdown the IC.
7. Over Voltage Protection (OVP)
The output voltage is continuously monitored for
Over Voltage Protection by FB pin. When it is larger
than 1.67 times as setting, the OVP function is
triggered. The Over Voltage Protection has 65µs
triggered delay.
5. Adjusting Output Voltage
The output voltage is set with a resistor divider from
the FB pin. It is recommended to use divider resistors
with 1% tolerance or better. Start with a 100kΩ for
the resistor R1 and use the following equation to
calculate R2. Consider using larger value resistors to
improve efficiency at very light loads. If the values
are too high, the regulator is more susceptible to
noise and the voltage errors caused by FB input
current are noticeable.
When OVP is triggered, both high side and low side
are shutdown immediately and the output voltage is
discharged by an internal 1kΩ resistor.
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
12
Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Application Information (Continued)
8. Power Good
100kΩ to a voltage source that is 5V or less.
The PGOOD pin output connects an open drain
MOSFET. The output is pulled low when the FB
voltage enters the fault condition by falling below
75% or rising above 125% of the nominal internal
reference voltage. There is a 7% hysteresis on the
threshold voltage, so when the FB voltage rises to the
good condition above 82% or falls below 118% of
the internal voltage reference the PGOOD output
MOSFET is turned off. It is recommended to use a
pull-up resistor between the values of 3kΩ and
9. Thermal Shutdown
The device implements an internal thermal shutdown
to protect itself if the junction temperature exceeds
160°C. Switching is stopped when the junction
temperature exceeds the thermal trip threshold. Once
the die temperature decreases below 140°C, the
device reinitiates the soft start operation. The thermal
shutdown hysteresis is 20°C.
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
13
Data Sheet
3A, 1.25MHz High Performance Synchronous Buck Converter
AP3436/A
Mechanical Dimensions
DFN-3×3-10
Unit: mm(inch)
0.300(0.012)
1.600(0.063)
0.500(0.020)
1.800(0.071)
0.500(0.020)
TYP
2.900(0.114)
3.100(0.122)
N6
N10
2.300(0.090)
2.500(0.098)
2.900(0.114)
3.100(0.122)
PIN#1 IDENTIFICATION
See DETAIL A
Pin 1 Mark
N5
N1
0.200(0.008)
0.700(0.028)
0.800(0.031)
0.300(0.012)
0.000(0.000)
0.050(0.002)
DETAIL A
0.153(0.006)
0.253(0.010)
2
1
2
1
2
1
Pin 1 options
Jan. 2013 Rev. 1.2
BCD Semiconductor Manufacturing Limited
14
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