UCC2941-3/-5/-ADJ
UCC3941-3/-5/-ADJ
application
INFO
available
1V Synchronous Boost Converter
FEATURES
DESCRIPTION
• 1V Input Voltage Operation Startup
Guaranteed Under Full Load on Main
Output With Operation Down to 0.4V
The UCC3941 family of low input voltage single inductor boost converters
are optimized to operate from a single or dual alkaline cell, and step up to
a 3.3V, 5V, or an adjustable output at 500mW. The UCC3941 family also
provides an auxiliary 9V 100mW output, primarily for the gate drive supply,
which can be used for applications requiring an auxiliary output such as a
5V supply by linear regulating. The primary output will start up under full
load at input voltages typically as low as 0.8V, with a guaranteed maximum
of 1V, and will operate down to 0.4V once the converter is operating, maximizing battery utilization.
• Input Voltage Range of 1V to VOUT +
0.5V
• 500mW Output Power at Battery
Voltages as Low as 0.8V
• Secondary 9V Supply From a Single
Inductor
• Adjustable Output Power Limit Control
• Output Fully Disconnected in
Shutdown
• Adaptive Current Mode Control for
Optimum Efficiency
• 8µA Shutdown Supply Current
Demanding applications such as Pagers and PDA’s require high efficiency
from several milli-watts to several hundred milli-watts, and the UCC3941
family accommodates these applications with >80% typical efficiencies
over the wide range of operation. The high efficiency at low output current
is achieved by optimizing switching and conduction losses along with low
quiescent current. At higher output current the 0.25Ω switch, and 0.4Ω synchronous rectifier, along with continuous mode conduction, provide high efficiency. The wide input voltage range on the UCC3941 family can
accommodate other power sources such as NiCd and NiMH.
Other features include maximum power control and shutdown control.
Packages available are the 8-pin SOIC (D) and 8-pin DIP (N or J).
SIMPLIFIED BLOCK DIAGRAM AND APPLICATION CIRCUIT
+
10µF
22µH
VIN
0.8V TO VOUT +0.5V
SW
3
UCC3941-3 = 3.3V
UCC3941-5 = 5.0V
UCC3941-ADJ = 1.30V TO 6V
VOUT
8
8V
VGD
0.4Ω
2
10µF
STARTUP
CIRCUITRY
1
0.25Ω
PLIM
5
SD
4
*SGND/FB
OPEN=SD
–
+
UCC3941-ADJ
6
1.25V
*FOR UCC3941-ADJ ONLY:
PIN 7 = SGND & PGND, PIN 6 = OUTPUT SENSE FEEDBACK, FB.
FOR UCC3941-ADJ ONLY
100µF
MODULATOR CONTROL CIRCUIT
SYNCHRONOUS RECTIFICATION CIRCUITRY
ANTI-CROSS CONDUCTION
STARTUP
MULTIPLEXING LOGIC
MAXIMUM INPUT POWER CONTROL
ADAPTIVE CURRENT CONTROL
PGND
7
UDG-98147
07/99
