MOTOROLA MC34280FTB, MC34280FTBR2 Datasheet

MC34280
Power Supply &

Management IC for Handheld
Electronic Products

The MC34280 is a power supply integrated circuit which provides
two boost regulated outputs and some power management supervisory
functions. Both regulators apply Pulse–Frequency–Modulation
(PFM). The main step–up regulator output can be externally adjusted
from 2.7V to 5V. An internal synchronous rectifier is used to ensure
high efficiency (achieve 87%). The auxiliary regulator with a built–in
power transistor can be configured to produce a wide range of positive
voltage (can be used for LCD contrast voltage). This voltage can be
adjusted from +5V to +25V by an external potentiometer; or by a
microprocessor, digitally through a 6–bit internal DAC.

The MC34280 has been designed for battery powered hand–held
products. With the low start–up voltage from 1V and the low quiescent
current (typical 35 µA); the MC34280 is best suited to operate from 1
to 2 AA/ AAA cell. Moreover, supervisory functions such as low
battery detection, CPU power–on reset, and back–up battery control,
are also included in the chip. It makes the MC34280 the best one–chip
power management solution for applications such as electronic
organizers and PDAs.

FEATURES:

• Low Input Voltage, 1V up

• Low Quiescent Current in Standby Mode: 35µA typical

• PFM and Synchronous Rectification to ensure high efficiency

(87% @200mA Load)

• Adjustable Main Output: nominal 3.3V @ 200mA max, with 1.8V

input

• Auxiliary Output Voltage can be digitally controlled by

microprocessor

• Auxiliary Output Voltage:

+5V @ 25mA max, with 1.8V input
+25V @ 15mA max, with 1.8V input

• Current Limit Protection

• Power–ON Reset Signal with Programmable Delay

• Battery Low Detection

• Lithium Battery Back–up

• 32–Pin LQFP Package

32

1

VMAINFB

VBAT

ENABLE

VDD

PDELAY

VREF

AGND

IREF

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32–LEAD LQFP

FTB SUFFIX

CASE 873A

MARKING DIAGRAM

MC34280F
TB
AWLYYWW

PIN CONNECTIONS

VMAIN

VMAINSW

VMAINGND

32

1

MC34280

PROB

DGND

LOWBATSEN

A = Assembly Location
WL = Wafer Lot
YY = Year
WW = Work Week

LIBAOUTNCLIBATIN

VAUXEMR

VAUXSW

NC
VAUXBASE
VAUXCHG
VAUXBDV
VAUXFBN
VAUXREF
VAUXFBP
VAUXEN

LIBATCL

LIBATON

LOWBATB

VAUXADJ

VAUXCON

APPLICATIONS:

• Digital Organizer and Dictionary

• Personal Digital Assistance (PDA)

• Dual Output Power Supply (For MPU, Logic, Memory, LCD)

• Handheld Battery Powered Device (1–2 AA/AAA cell)

 Semiconductor Components Industries, LLC, 1999

February , 2000 – Rev. 2

1 Publication Order Number:

ORDERING INFORMATION

Device Package Shipping

MC34280FTB LQFP 250 Units/Tray

MC34280FTBR2 LQFP 1800 Tape & Reel

MC34280/D

GND

Riref

r = 480 k

I

REF

MC34280

Figure 1. T ypical Application Block Diagram

Battery

4

Lock

Switch

GND

DD

VBAT

Ren

r = 1000 k

ENABLE
321

GND

AGND

V

REF

87

GND

V

REF

65

CVDD

c = 20u

Cpor

c = 80n

GND

PDELAY V

V

DD

VMAINFBVBAT

CMAINb
c = 100p

RMAINb

r = 1000 k

VBAT

Optional

CMAINbp
c = 100u

10 V SMT
tantalum

GND

PORB
LOWBAT
LIBATON

LIBATCL

VAUXADJ

VAUXCON

VAUXEN

VBAT

RLBa

r = 300 k

RLBb

r = 900 k

LOWBATSEN

DGND

GNDGND

PORB

LOWBATB

LIBATON

LIBATCL

VAUXADJ

VAUXCON

VAUXEN

9
10

11

12
13
14

15

16

17

VAUXFBP

R123

Power

ON

Reset

Current

Voltage

Reference

Lithium
Battery
Backup

Level

Control

Auxiliary Regulator

18 20 2119 22 23 24

VAUXREF
(1.1 V to 2.2 V)

Bias

Low

Battery

Detect

Current

Limit

VAUXFBN

VBAT

Control and

Gate Drive

Startup

Current

Limit

Main Regulator with
Synchronous Rectifier

Control and

Base Drive

VAUXBDV

s

M2

d

M1

s

Q1

VAUXBASE

VAUXCHG

r = 5

d

d

s

N/C

32

31

30
29

28

M3

27

26

25

VMAIN

1N5817

VMAINSW
VMAINGND

N/C

LIBATOUT

LIBATIN

VAUXEMR

VAUXSW

LMAIN
L = 33u
(Rs < 60 mOhm)

VMAIN

GND

GND

GND

CMAIN
c = 100u

10 V SMT
tantalum

GND

VBAT

Optional

LAUX

L = 22u

(Rs < 60 mOhm)

CAUXbp
c = 100u

10 V SMT
tantalum

GND

1N5818

30 V SMT

tantalum

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2

Caux
c = 30u

GND

VAUX

Rauxb
r = 2.2 M

Rauxa
r = 200 k

GND

Optional

CAUXb
c = 2n

CAUXa
c = 33n

VBAT

ENABLE

VMAIN

PORB

VAUXEN

V

MAINreg

– 0.15 V

MC34280

TIMING DIAGRAMS

Figure 2. Startup Timing

T

POR

t

PORC

+

V

MAINreg

1.22

ǒ

0.5

Ǔ

C

RIref

por

VBAT

LOWBATB

VMAIN

ENABLE

PORB

LOWBAT Threshold

Figure 3. Power Down Timing

V

MAINreg

– 0.5 V

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3

MC34280

TIMING DIAGRAMS (Con’t)

VAUXCON

VAUXADJ

VAUXREF

1.1 V

T otal N Pulses Total M Pulses

N

DV+

64

@

1.1 V

“Countup”

Flag is HIGH

Figure 4. Auxiliary Regulator Voltage Control

t

CW

t

CL

“Countup”
Flag is LOW

t

CC

M

@

64

1.1 V

t

RJL

Reset
VAUXREF

DV+

t

DL

2.2 V

1.65 V

VAUXCON

VAUXADJ

t

JC

t

JW

t

JL

t

DW

t

RW

Figure 5. Auxiliary Regulator Voltage Control Timing

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4

Pin

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Á

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Á

Á

Á

Á

Á

Á

Á

Á

Á

Á

Á

Á

Á

Á

Á

No.

1

2

3

ÁÁ

4

5

6

7

8

9

10
11
12
13

ÁÁ

14

ÁÁ

15
16
17
18
19
20
21
22
23
24
25
26
27
28
29

ÁÁ

30
31
32

MC34280

PIN FUNCTION DESCRIPTION

Function Type/Direction Description

VMAINFB

VBAT

ENABLE

ÁÁÁÁ

VDD

PDELAY

VREF

AGND

IREF

LOWBATSEN

DGND
PORB

LOWBATB

LIBATON

ÁÁÁÁ

LIBATCL

ÁÁÁÁ

VAUXADJ

VAUXCON

VAUXEN
VAUXFBP
VAUXREF
VAUXFBN
VAUXBDV
VAUXCHG

VAUXBASE

NC

VAUXSW
VAUXEMR

LIBATIN

LIBATOUT

NC

ÁÁÁÁ

VMAINGND

VMAINSW

VMAIN

Analog / Input

Power

CMOS / Input

БББББ

Analog / Output

Analog / Input

Analog / Output

Feedback pin for VMAIN
Main battery supply
Chip enable, Active high, ENABLE activates VMAIN after battery plug in,

ENABLE is inactive after VMAIN is on

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Connect to decoupling capacitor for internal logic supply
Capacitor connection for defining Power–On signal delay
Bandgap Reference output voltage. Nominal voltage is 1.25V

Analog Ground

Analog / Input
Analog / Input

Resistor connection for defining internal current bias and PDELAY current
Resistive network connection for defining low battery detect threshold

Digital Ground
CMOS / Output
CMOS / Output

CMOS / Input

БББББ

CMOS / Input

БББББ

CMOS / Input
CMOS / Input
CMOS / Input
Analog / Input

Analog / Output

Analog / Input

Power
Analog / Output
Analog / Output

Active LOW Power–On reset signal
Active LOW low battery detect output
microprocessor control signal for Lithium battery backup switch, the switch is

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ON when LIBATON=HIGH and LIBATCL=HIGH
microprocessor control signal for Lithium battery backup switch, if it is HIGH,

the switch is controlled by LIBATON, otherwise, controlled by internal logic

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microprocessor control signal for VAUX voltage control
microprocessor control signal for VAUX voltage control
VAUX enable, Active high
Feedback pin for VAUX
Reference Voltage for VAUX voltage level
Feedback pin for VAUX
VAUX BJT base drive circuit power supply
test pin
test pin

no connection
Analog / Output
Analog / Output

Analog / Input

Analog / Output

БББББÁБББББББББББББББББ

Power Ground

Analog / Input

Analog / Output

Collector output of the VAUX power BJT

Emitter output of the VAUX power BJT

Lithium battery input for backup purposes

Lithium battery output

no connection

Ground for VMAIN low side switch

VMAIN inductor connection

VMAIN output

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5

MC34280

ABSOLUTE MAXIMUM RATINGS (T

Parameter

Power Supply Voltage
Digital Pin Voltage V
General Analog Pin Voltage V
Pin VAUXSW to Pin VAUXEMR Voltage (Continuous) V

Pin VMAINSW to Pin VMAIN Voltage (Continuous)
Operating Junction Temperature
Ambient Operating Temperature
Storage Temperature

STATIC ELECTRICAL CHARACTERISTICS (Circuit of Figure 1, VP = 1.8V, I

= 25°C, unless otherwise noted.)

A

Symbol Min Max Unit

V

BAT

digital

analog

AUXCE

V

syn

Tj

(max)

T

a

T

stg

load

–0.3

7.0
–0.3 7.0 Vdc
–0.3 7.0 Vdc
–0.3 30 Vdc

0.3

150

0

–50

70

150

= 0 mA, TA = 0 to 70°C unless

Vdc

Vdc

°C
°C
°C

otherwise noted.)

Rating

Operating Supply Voltage

1

VMAIN output voltage V
VMAIN output voltage range
VMAIN output current
VMAIN maximum switching frequency

2

3

4

VMAIN peak coil static current limit I

Symbol Min Typ Max Unit

V

BAT

main

V

main_range

I

3.3_1.8

Freq

max_VM

LIM_VM

1.0 V

3.13 3.3 3.47 V

2.7 5.0 V
200 mA
100 kHz

0.85 1.0 1.15 A
VAUX output voltage range VAUX_range 5.0 25 V
VAUXREF lower level voltage VAUX
VAUXREF upper level voltage VAUX
VAUXREF step size VAUX
VAUX maximum switching frequency Freq
VAUX peak coil static current limit I
Quiescent Supply Current at Standby Mode

5

Reference Voltage @ no load Vref
Battery Low Detect lower hysteresis threshold

6

Battery Low Detect upper hysteresis threshold V
PDELAY Pin output charging current Ichg
PDELAY Pin voltage threshold Vth

NOTE: 1. Output current capability is reduced with supply voltage due to decreased energy transfer. The supply voltage must not be higher than
NOTE: 2. Output voltage can be adjusted by external resistor to the VMAINFB pin.

NOTE: 3. At VBAT = 1.8V, output current capability increases with VBAT .
NOTE: 4. Only when current limit is not reached.
NOTE: 5. This is average current consumed by the IC from VDD, which is low–pass filtered from VMAIN, when only VMAIN is enabled and at no loading.
NOTE: 6. This is the minimum of ”LOWBATB” threshold for battery voltage, the threshold can be increased by external resistor divider from ”VBA T” to

VMAIN+0.6V to ensure boost operation. Max Start–up loading is typically 1V at 400 µA, 1.8V at 4.4 mA, and 2.2V at 88 mA.

”LOWBATSEN”.

REF_L
REF_H
REF_S

max_VL

LIM_VL

Iq

standby

no_load

V

LOBAT_L

LOBAT_H

PDELAY

PDELAY

1.0 1.1 1.2 V

2.0 2.2 2.4 V
17 mV

120 kHz

1.0 A
35 60 µA

1.19 1.22 1.25 V

0.8 0.85 0.9 V

1.05 1.1 1.15 V

0.8 1.0 1.2 µA

1.19 1.22 1.25 V

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