Texas Instruments UCC3941D-ADJ, UCC3941D-5, UCC3941D-3, UCC3941N-ADJ, UCC3941N-5 Datasheet

UCC2941-3/-5/-ADJ
UCC3941-3/-5/-ADJ

SLUS242 - JULY 1999

FEATURES

•

1V Input Voltage Operation Startup
Guaranteed Under Full Load on Main
Output With Operation Down to 0.4V

•

Input Voltage Range of 1V to V

OUT

+

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

1V Synchronous Boost Converter

MODULATOR CONTROL CIRCUIT
SYNCHRONOUS RECTIFICATION CIRCUITRY
ANTI-CROSS CONDUCTION
STARTUP
MULTIPLEXING LOGIC
MAXIMUM INPUT POWER CONTROL
ADAPTIVE CURRENT CONTROL

4

5

6

7

1

8

3

2

+

–

1.25V

UCC3941-ADJ

OPEN=SD

SD

10µF

VGD

8V

STARTUP

CIRCUITRY

VIN SW

+

10µF

22µH

0.8V TO VOUT +0.5V

100µF

0.4Ω

VOUT

PGND

*SGND/FB

PLIM

0.25Ω

UCC3941-3 = 3.3V
UCC3941-5 = 5.0V
UCC3941-ADJ = 1.30V TO 6V

*FOR UCC3941-ADJ ONLY:
PIN 7 = SGND & PGND, PIN 6 = OUTPUT SENSE FEEDBACK,FB.

FOR UCC3941-ADJ ONLY

SIMPLIFIED BLOCK DIAGRAM AND APPLICATION CIRCUIT

UDG-98147

DESCRIPTION

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, maxi

-

mizing battery utilization.
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 0.25Ωswitch, and 0.4Ω syn

-

chronous rectifier, along with continuous mode conduction, provide high ef

­ficiency. 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).

application

INFO

available

2

UCC2941-3/-5/-ADJ
UCC3941-3/-5/-ADJ

ELECTRICAL CHARACTERISTICS: Unless otherwise specified, for UCC3941, T

A

= 0°C to 70°C; for UCC2941, TA= –40°C

to 85°C; VIN = 1.25V, T

A=TJ

.

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

VIN Section

Minimum Startup Voltage No External VGD Load, T

J

= 25°C, IOUT = 100mA (Note 1) 0.8 1.0 V

Minimum Start Voltage No External VGD Load, I

OUT

= 100mA, TJ= 0°C to 85° C

(Note 1)

0.9 1.1 V

Minimum Startup Voltage No External VGD Load, T

J

= –40°C to 0°C 0.9 1.5 V

Minimum Dropout Voltage No External VGD Load, I

OUT

= 100mA, VGD = 6.3V

(Note 1)

0.5 V

Input Voltage Range 1 VOUT

+0.5

V

Quiescent Supply Current (Note 2) 13 25 µA
Supply Current at Shutdown SD = Open 8 20 µA

Output Section

Quiescent Supply Current (Note 2) 32 80 µA
Supply Current at Shutdown SD = Open 6 15 µA
Regulation Voltage (UCC3941-3) 1V < VIN < 3V 3.18 3.25 3.37 V

1V < VIN < 3V, 0mA < I

OUT

< 150mA (Note 1) 3.17 3.30 3.43 V

Regulation Voltage (UCC3941-5) 1V < VIN < 5V 4.85 5.00 5.15 V

1V < VIN < 5V, 0mA < I

OUT

100mA (Note 1) 4.8 5.0 5.2 V

FB Voltage (UCC3941-ADJ) 1V < VIN < 3V 1.212 1.250 1.288 V

VGD Output Section

Quiescent Supply Current (Note 2) 25 60 µA
Supply Current at Shutdown SD = Open 8 20 µA
Regulation Voltage 1V < VIN < 3V 7.5 8.7 9.2 V

1V < VIN < 3V, 0mA < I

OUT

< 10mA (Note 1) 7.4 8.7 9.3 V

Inductor Charging Section (L = 22µH)

Peak Discontinuous Current Over Operating Range 0.50 0.85 A
Peak Continuous Current R

PLIM

= 6.2Ω, UCC3941-3 and UCC3941-5 0.5 0.8 1.1 A

UCC3941-ADJ 0.6 0.9 1.3 A

ABSOLUTE MAXIMUM RATINGS

VIN Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to 10V

SD Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to VIN

PLIM Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to 10V

VGD Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to 15V

SW Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to 15V

VOUT Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to 10V

Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C

Junction Temperature. . . . . . . . . . . . . . . . . . . –55°C to +150°C

Lead Temperature (Soldering, 10 sec.). . . . . . . . . . . . . +300°C

Currents are positive into, negative out of the specified terminal.
Consult Packaging Section of Databook for thermal limitations
and considerations of packages.

Pin 6 is FB for UCC3941-ADJ.

CONNECTION DIAGRAM

DIL-8, SOIC-8 (Top View)
N or J Package, D Package

3

UCC2941-3/-5/-ADJ
UCC3941-3/-5/-ADJ

ELECTRICAL CHARACTERISTICS: Unless otherwise specified, for UCC3941, T

A

= 0°C to 70°C; for UCC2941, TA= –40°C

to 85°C; VIN = 1.25V, T

A=TJ

.

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

Inductor Charging Section

Charge Switch R

DS(on)

N and D Package, I = 200mA 0.25 0.4 Ω

Current Limit Delay (Note 1) 50 ns

Synchronous Rectifier Section

Rectifier R

DS(on)

N and D Package, I = 200mA, UCC3941-ADJ V

OUT

= 3.3V

and UCC3941–3

0.35 0.6 Ω

N and D Package, I = 200mA, UCC3941-5 0.5 0.8 Ω

Shutdown Section

Shutdown Bias Current –10 –7 µA

Note 1: Performance from application circuit shown in Figures 3 - 5 guaranteed by design and alternate testing methods, but not

100% tested as shown in production.

Note 2: For the UCC3941-3, VOUT = 3.47V and VGD = 9.3V.For the UCC3941-5, VOUT = 5.25V, VGD = 9.3V.For the UCC3941-

ADJ, FB = 1.315V, VGD = 9.3V.

PIN DESCRIPTIONS

FB: Feedback control pin used in the UCC3941-ADJ

version only. The internal reference for this comparator is

1.25V and external resistors provide the gain to the
output voltage.

PGND: Power ground of the IC. The inductor charging
current flows through this pin. For the UCC3941-ADJ
signal ground and power ground lines are tied to a
common pin.

PLIM: This pin is programmed to set the maximum input
power for the converter. For example a 1A current limit at
1V would have a 333mA limit at 3V input keeping the
input power constant at 1W. The peak current at VIN =
1V is programmed to 1.5A (1.5W) when this pin is
grounded.The power limit is given by:

PL

n

R

V

W

PL

IN

()

.

.

(. )=

•

+

+

11 8

67

026

where R

PL

is equal to the external resistor from the PLIM

pin to ground and

n

is the expected efficiency of the

converter.The peak current limit is given by:

()

I

n

VR

PK

A

IN PL

()

.

.

.=

•

•+

+

11 8

67

026

Constant power gives several advantages over constant
current such as lower output ripple.

SD: When this pin is open, the built in 7µA current source
pulls up on the pin and programs the IC to go into
shutdown mode. This pin requires an open circuit for
shutdown and will not operate correctly when driven to a
logic level high with TTL or CMOS logic. When this pin is
connected to ground, (either directly or with a transistor)
the IC is enabled and both output voltages will regulate.

SGND: Signal ground of the IC. For the UCC3941-ADJ
signal ground and power ground lines are tied to a
common pin.

SW: An inductor is connected between this node and
VIN. The VGD (Gate Drive Supply) flyback diode is also
connected to this pin. When servicing the 3.3V supply,
this pin will go low charging the inductor, then shut off,
dumping the energy through the synchronous rectifier to
the output. When servicing the VGD supply, the internal
synchronous rectifier stays off, and the energy is diverted
to VGD through the flyback diode. During discontinuous
portions of the inductor current a MOSFET resistively
connects VIN to SW damping excess circulating energy
to eliminate undesired high frequency ringing.

VGD: The VGD pin which is coarsely regulated around
9V and is primarily used for the gate drive supply for the
power switches in the IC. This pin can be loaded with up
to 10mA as long as it does not present a load at voltages
below 2V. This ensures proper startup of the IC. The
VGD supply can go as low as 7.5V without interfering
with the servicing of the 3.3V output. Below 7.5V, VGD
will have the highest priority, although practically the
voltage should not decay to that level if the output
capacitor is sized properly.

VIN: Input voltage to supply the IC during startup. After
the output is running the IC draws power from VOUT or
VGD.

VOUT: Main output voltage (3.3V, 5V or adjustable)
which has highest priority in the multiplexing scheme, as
long as VGD is above the critical level of 7.5V. Loads
over 150mA are achievable at 1V input voltage. This
output will startup with 1V input at full load.

4

UCC2941-3/-5/-ADJ
UCC3941-3/-5/-ADJ

4

5

2

3 8

1

6

6

7

SD

PLIM

VGD

VIN

SW

VOUT

FB FOR
UCC3941-ADJ
ONLY

PGND

SGND FOR
UCC3941-3/-5

5Ω

+
–

+
–

+

–

VGD

+
–

+

–

+

–

+

–

* 3.3VFOR UCC3941-3

5.0V FORUCC3941-5

1.25V FORUCC3941-ADJ

VGD

** 8.7VFOR UCC3941-3

9.6V FORUCC3941-5/-ADJ

VGD

*** 7.7VFOR UCC3941-3

8.8V FORUCC3941-5/-ADJ

FROM

SD

5V

1.4A
MAX

CURRENT

LIMIT

50mV

VIN

VIN

SD

50mV

MAXIMUM

200kHz

STARTUP

OSCILATOR

AND CONTROL

VGD

VGD

VGD ZERO

DETECT

VOUT ZERO

DETECT

ANTI-RINGING

SWITCH

1.7µS

OFF TIME

CONTROLLER

RECTIFIER

CONTROL

FROM SD

CLK

DQ

L1

RQ

SD

BOOST
LATCH

ON TIME

CONTROLLER

T

ON

=

11µSEC

VIN

VSAT

*

**

***

THERMAL

SHUTDOWN

RQ

SD

Figure 1. 1V Synchronous boost.

UDG-98146

Note: Switches are shown in the logic low state.

A detailed block diagram of the UCC3941 is shown in
Fig. 1. Unique control circuitry provides high efficiency
power conversion for both light and heavy loads by tran

-

sitioning between discontinuous and continuous conduc

-

tion based on load conditions. Fig. 2 depicts converter

waveforms for the application circuit shown in Fig. 3. A
single 22µH inductor provides the energy pulses required
for a highly efficient 3.3V converter at up to 500mW out

-

put power.

APPLICATION INFORMATION