TC1303B
500 mA Synchronous Buck Regulator,
+ 300 mA LDO with Power-Good Output
Features
Description
• Dual-Output Regulator (500 mA Buck Regulator
and 300 mA Low-Dropout Regulator)
The TC1303B combines a 500 mA synchronous buck
regulator and 300 mA Low-Dropout Regulator (LDO)
with a power-good monitor to provide a highly
integrated solution for devices that require multiple
supply voltages. The unique combination of an
integrated buck switching regulator and low-dropout
linear regulator provides the lowest system cost for
dual-output voltage applications that require one lower
processor core voltage and one higher bias voltage.
• Power-Good Output with 300 ms Delay
• Total Device Quiescent Current = 65 µA, Typ.
• Independent Shutdown for Buck and LDO
Outputs
• Both Outputs Internally Compensated
• Synchronous Buck Regulator:
- Over 90% Typical Efficiency
The 500 mA synchronous buck regulator switches at a
fixed frequency of 2.0 MHz when the load is heavy
providing a low noise, small-size solution. When the
load on the buck output is reduced to light levels, it
changes operation to a Pulse Frequency Modulation
(PFM) mode to minimize quiescent current draw from
the battery. No intervention is necessary for smooth
transition from one mode to another.
- 2.0 MHz Fixed Frequency PWM
(Heavy Load)
- Low Output Noise
- Automatic PWM to PFM mode transition
- Adjustable (0.8V to 4.5V) and Standard Fixed
Output Voltages (0.8V, 1.2V, 1.5V, 1.8V, 2.5V,
3.3V)
The LDO provides a 300 mA auxiliary output that
requires a single 1 µF ceramic output capacitor,
minimizing board area and cost. The typical dropout
voltage for the LDO output is 137 mV for a 200 mA
load.
• Low-Dropout Regulator:
- Low-Dropout Voltage = 137 mV Typ. @
200 mA
- Standard Fixed Output Voltages
(1.5V, 1.8V, 2.5V, 3.3V)
For the TC1303B, the power-good output logic level is
based on the regulation of the LDO output only. The
buck regulator can be turned on and off without affecting
the power-good signal.
• Power-Good Function:
- Monitors LDO Output Function (TC1303B)
- 300 ms Delay Used for Processor Reset
• Small 10-pin 3X3 DFN or MSOP Package
Options
The TC1303B is available in either the 10-pin DFN or
MSOP package.
• Operating Junction Temperature Range:
- -40°C to +125°C
Additional protection features include: UVLO,
overtemperature and overcurrent protection on both
outputs.
• Undervoltage Lockout (UVLO)
• Output Short Circuit Protection
• Overtemperature Protection
For a complete listing of TC1303B standard parts, con-
sult your Microchip representative.
Applications
Package Type
• Cellular Phones
10-Lead DFN
10-Lead MSOP
• Portable Computers
• USB Powered Devices
• Handheld Medical Instruments
• Organizers and PDAs
P
10
9
SHDN2
1
2
3
4
5
P
GND
SHDN2
1
2
3
4
5
10
9
GND
V
L
V
L
IN2
X
IN2
X
V
V
8
IN1
V
OUT2
OUT2
V
IN1
8
7
SHDN1
PG
7
SHDN1
PG
V
/V
A
6
FB1 OUT1
GND
A
6
GND
V
/V
FB1 OUT1
© 2005 Microchip Technology Inc.
DS21949A-page 1