Diodes PAM2312 User Manual
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Description
The PAM2312 is a step-down current-mode, DC-DC converter. At
heavy load, the constant frequency PWM control performs excellent
stability and transient response. To ensure the longest battery life in
portable applications, the PAM2312 provides a power-saving
Pulse- Skipping Modulation (PSM) mode to reduce quiescent current
under light load operation to save power.
The PAM2312 supports a range of input voltages from 2.5V to 5.5V,
allowing the use of a single Li+/Li-polymer cell, multiple Alkaline/NiMH
cell, USB, and other standard power sources. The output voltage is
adjustable from 0.6V to the input voltage, while the part number suffix
PAM2312-XX indicates pre-set output voltage of 3.3V, 2.8V, 2.5V,
1.8V, 1.5V, 1.2V or adjustable. All versions employ 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 1µA. Other key
features include under-voltage lockout to prevent deep battery
discharge.
The PAM2312 is available in TSOT25 packages.
Features
• Efficiency up to 96%
• Only 40µA (typ) Quiescent Current
• Output Current: Up to 1A
• Internal Synchronous Rectifier
• 1.5MHz Switching Frequency
• Soft Start
• Under-Voltage Lockout
• Short Circuit Protection
• Thermal Shutdown
• 5-pin Small TSOT25 Packages
• Pb-Free Package
Typical Applications Circuit
Fixed Output Voltage Adjustable Output Voltage
Diodes Incorporated
1A STEP-DOWN DC-DC CONVERTER
Pin Assignments
Applications
• Cellular Phone
• Portable Electronics
• Wireless Devices
• Cordless Phone
• Computer Peripherals
• Battery Powered Widgets
• Electronic Scales
• Digital Frame
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Top View
TSOT25
PAM2312
PAM2312
Document number: DSxxxxx Rev. 2 - 0
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1R
⎛
⎜
⎝
⎞
+=
1x6.0
⎟
2R
⎠
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Pin Descriptions
Pin
Name
4 VIN
2 GND
1 EN
5 VOUT/FB
3 SW
TSOT25
Pin Name
Chip main power supply pin.
Ground
Enable Control Input. Force this pin voltage above 1.5V, enables the chip, and below
0.3V shuts down the device.
VOUT: Output voltage feedback pin, an internal resistive divider divides the output
voltage down for comparison to the internal reference voltage.
FB: Feedback voltage to internal error amplifier, the threshold voltage is 0.6V.
The drains of the internal main and synchronous power MOSFET.
Functional Block Diagram
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PAM2312
Function
Absolute Maximum Ratings (@T
These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may
affect device reliability. All voltages are with respect to ground.
Parameter Rating Unit
Inout Voltage -0.3 to +6.0 V
EN, FB Pin Voltage
SW Pin Voltage
Junction Temperature 150 °C
Storage Temperature Range -65 to +150 °C
Soldering Temperature 300, 5sec °C
PAM2312
Document number: DSxxxxx Rev. 2 - 0
= +25°C, unless otherwise specified.)
A
-0.3 to V
-0.3 to (V
+0.3)
IN
IN
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PAM2312
Recommended Operating Conditions (@T
Parameter Rating Unit
Supply Voltage 2.5 to 5.5 V
Operation Temperature Range -40 to +85
Junction Temperature Range -40 to +125
= +25°C, unless otherwise specified.)
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°C
Thermal Information
Parameter Package Symbol Max Unit
Thermal Resistance (Junction to Case)
Thermal Resistance (Junction to Ambient)
Internal Power Dissipation
Note: 1. The maximun output current for TSOT25 package is limited by internal power dissipation capacity as described in
Application Information here inafter.
PAM2312
Document number: DSxxxxx Rev. 2 - 0
TSOT25 (Note 1)
TSOT25
TSOT25
θ
JC
θ
JA
P
D
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130
250
400 mW
°C/W
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PAM2312
Electrical Characteristics (@T
Parameter Symbol Test Conditions Min Typ Max Units
Input Voltage Range
Regulated Feedback Voltage
Reference Voltage Line Regulation
Regulated Output Voltage Accuracy
Peak Inductor Current
Putput Voltage Line Regulation LNR
Output Voltage Load Regulation LDR
Quiescent Current
Shutdown Current
Oscillator Frequency
Drain-Source On-State Resistance
SW Leakage Current
High Effiency η 96 %
EN Threshold High
EN Threshold Low
EN Leakage Current
Over Temperature Protection OTP 150 °C
OTP Hysteresis OTH 30 °C
PAM2312
Document number: DSxxxxx Rev. 2 - 0
= +25°C, VIN = 3.6V, VO = 1.8V, CIN = 10µF, C
A
IN
FB
FB
IO = 100mA
O
VIN = 3V, VFB = 0.5V or VO = 90%
V
= 2.5V to 5v, IO = 10mA
IN
I
= 800mA
O
No Load 40 70 µA
Q
VEN = 0V
= 100%
V
O
VFB = 0V or VO = 0V
IDS = 100mA
±0.01 1 µA
1.5 V
EH
0.3 V
EL
±0.01 µA
P MOSFET 0.3 0.45 Ω
N MOSFET 0.35 0.5 Ω
V
ΔV
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R
DS(ON)
I
V
V
V
V
I
PK
I
I
SD
OSC
LSW
I
EN
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= 10µF, L = 4.7µH, unless otherwise specified.)
OUT
2.5 5.5 V
0.588 0.6 0.612 V
0.3 %/V
-3 +3 %
1.5 A
0.2 0.5 %/V
0.5 1.5 %
1 µA
1.2 1.5 1.8 MHz
500 KHz
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© Diodes Incorporated
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Typical Performance Characteristics (@T
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PAM2312
= +25°C, CIN = 10µF, CO = 10µF, L = 4.7µH, unless otherwise specified.)
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PAM2312
Document number: DSxxxxx Rev. 2 - 0
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