Page 1
AP3429
EVB User Guide
This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without
notice.
No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product.
1 of 4
www.diodes.com
September 2018
© Diodes Incorporated
AP3429 EV Board User Guide
1. AP3429 General Description
The AP3429/AP3429A is a 2A step-down DC-DC converter. At heavy load, the
constant-frequency PWM control performs excellent stability and transient response. No external
compensation components are required.
The AP3429/AP3429A supports a range of input voltages from 2.7V to 5.5V, allowing the use of
a single Li+/Li-polymer cell, multiple Alkaline/NiMH cell, and other standard power sources. The
output voltage is adjustable from 0.6V to the input voltage. The AP3429/AP3429A employs internal
power switch and synchronous rectifier to minimize external part count and realize high efficiency.
During shutdown, the input is disconnected from the output and the shutdown current is less than 1
μA. Other key features include over-temperature and short circuit protection, and under-voltage
lockout to prevent deep battery discharge.
The AP3429/AP3429A delivers 2A maximum output current while consuming only 48μA of
no-load quiescent current. Ultra-low RDS(ON) integrated MOSFETs and 100% duty cycle operation
make the AP3429/AP3429A an ideal choice for high output voltage, high current applications which
require a low dropout threshold.
The AP3429/AP3429A is available in SOT23-5 packages.
2． Key Features
Output Current: Up to 2A
Output Voltage: 0.6V to Vin
Input Voltage: 2.7V to 5.5V
Shutdown Current: <1μA
100% Duty Cycle Operation
1MHz Switching Frequency
Internal Soft Start
No external Compensation Required
Short Circuit Protection
AP3429: Latch Off Protection
AP3429A: Hiccup Mode Protection
Over –voltage Protection
AP3429 :Latch Off Protection
AP3429A :No Latch Off Protection
Thermal Shutdown
SOT23-5 Packages
Page 2
AP3429
EVB User Guide
This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without notice.
No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product.
2 of 4
www.diodes.com
September 2018
© Diodes Incorporated
3． EV Board Schematic
4． EVB AP3429 Description
AP3429 EVB is suitable evaluation board for the AP3429/A, a DC/DC converter. The board is
targeted to be used in providing a simple and convenient evaluation environment for the AP3429/A.
Requires parts, power supply connectors etc. on the board, which makes it easy to be evaluated.
R1
R2
VIN
EN
SW
FB
L1
CIN
VIN
GND
Cout
V
OUT
ON OFF
AP3429A
CF
Page 3
AP3429
EVB User Guide
This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without
notice.
No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product.
3 of 4
www.diodes.com
September 2018
© Diodes Incorporated
5. EV Board View
6. Resistor select for output voltage setting
Vout = (1+R1/R2)×Vref (Vref=0.6V)
Vo
R1
R2
L1
3.3V
211k
47k
2.2uH
1.8V
300k
150k
2.2uH
1V
100k
150k
2.2uH
Page 4
AP3429
EVB User Guide
This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without
notice.
No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product.
4 of 4
www.diodes.com
September 2018
© Diodes Incorporated
7. External Components Selection
Input & output Capacitors (Cin)
(1) For lower output ripple, low ESR is required.
(2) Low leakage current needed, X5R/X7R ceramic recommend, multiple capacitor parallel
connection.
Output Voltage programmer resistors (R1, R
2/4
)
(1) For programmer output voltage
(2) For accurate output voltage, 1% tolerance is required.
Inductor (L1)
(1) Low DCR for good efficiency
(2) Inductance saturate current must higher than the output current
8. Evaluation board BOM list for AP3429/3429A:
Item
Value
Type
Rating
Description
Description
CIN
22uF
X5R/X7R,
Ceramic/0805
10V
Input coupling CAP
TAIYO YUDEN
EMK212ABJ106KD-T
COUT
22uF×2
X5R/X7R,
Ceramic/0805
10V
Output coupling
CAP
TAIYO YUDEN
EMK212ABJ106KD-T
L1
2.2uH
>3A
Inductor
CDMC6D28NP-2R2M
R1
300K
0805
1%
Voltage set RES*
R2
150K
0805
1% R4
Floating
Parallel Res of R2
CF
22pF
0805
Feedforward CAP
IC
AP3429/3429A
SOT23-5
*Note: The present value of R1/R2 are based on Vout=1.8V
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