Rainbow Electronics MAX1621 User Manual

General Description

The MAX1620/MAX1621 convert a 1.8V to 20V battery voltage to a positive or negative LCD backplane bias voltage. Backplane bias voltage can be automatically disabled when the display logic voltage is removed, protecting the display. These devices use very little PC board area, come in ultra-small QSOP packages, and require only small, low-profile external components.

Output voltage can be set to a desired positive or negative voltage range with external resistors, and adjusted over that range with the on-board digital-to-analog converter (DAC) or with a potentiometer. The MAX1620/ MAX1621 include a 5-bit DAC, allowing digital software control of the bias voltage. The MAX1620 uses up/down digital signaling to adjust the DAC, and the MAX1621 uses the System Management Bus (SMBus™) 2-wire serial interface.

These devices use a low-cost, external, N-channel MOSFET power switch or NPN transistor, and can be configured for positive or negative output voltages. Operating current is a low 150µA, typically provided from a display’s logic supply of 3.0V to 5.5V. The MAX1620/MAX1621 are available in a 16-pin QSOP package.

Applications

Notebook Computers Palmtop Computers Personal Digital Assistants Portable Data-Collection Terminals

Features

♦ 1.8V to 20V Battery Input Voltage ♦ Automatic Disable when Display Logic

is Shut Down

♦ Extremely Small QSOP Package ♦ 32-Level Internal DAC ♦ SMBus Serial Interface (MAX1621) ♦ Positive or Negative Output Voltage

MAX1620/MAX1621

Digitally Adjustable LCD Bias Supplies

________________________________________________________________

Maxim Integrated Products

PART

MAX1620EEE MAX1621EEE

-40°C to +85°C

TEMP. RANGE PIN-PACKAGE

16 QSOP 16 QSOP

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

Ordering Information

19-1214; Rev 1; 1/98

DHI

DLO

PGND

DOUT

POL

SHDN DN

REF

AGND

MAX1620

12.5V TO

23.5V OUT

2V TO

12V

3V TO

5.5V

OFF

DOWN

LCDONPOK

BATT

Typical Operating Circuit

SMBus is a trademark of Intel Corp.

Pin Configuration

16 15 14 13 12 11 10

1 2 3 4 5 6 7

DHI DLO LX PGND AGND V

DOUT FB

DN (SDA)

UP (SCL)

BATT

SHDN (SUS)

POK

REF

POL

LCDON

TOP VIEW

MAX1620 MAX1621

QSOP

( ) ARE FOR MAX1621 ONLY.

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.

MAX1620/MAX1621

Digitally Adjustable LCD Bias Supplies

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VDD= 3.3V, V

BATT

= 10V, TA= 0°C to +85°C, unless otherwise noted.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

VDDto AGND..............................................................-0.3V to 6V

PGND to AGND ..................................................................±0.3V

BATT, LX,

LCDON to AGND....................................-0.3V to 30V

DHI, DLO to PGND.....................................-0.3V to (V

+ 0.3V)

DOUT, FB, POL, POK, REF to AGND.........-0.3V to (V

+ 0.3V)

UP, DN, SHDN to AGND.............................................-0.3V to 6V

SCL, SDA, SUS to AGND............................................-0.3V to 6V

DHI

......................................................................................60mA

DLO

....................................................................................-30mA

LCDON

...............................................................................-10mA

Continuous Power Dissipation (T

= +70°C)

QSOP (derate 8.3mW/°C above +70°C) ......................667mW

Operating Temperature Range

MAX1620EEE/MAX1621EEE ............................-40°C to +85°C

Storage Temperature Range.............................-65°C to +150°C

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

LCDON

= 28V, POK = 0.967V

LCDON

= 0.4V, POK = 1.017V

FB = -50mV

FB = REF + 100mV

POL = AGND, 3.0V ≤ V

≤ 5.5V

Shutdown mode, V

SHDN

= VDD,VDD= 5.5V

POL = VDD, 3.0V ≤ V

≤ 5.5V

Operating mode, output in regulation, VDD= 5.5V

VDD= 5V

VDD= 3.0V

LX = 12V, shutdown mode

VDD= 4.5V

LX = 12V, operating mode

BATT = 12V, shutdown mode

4V ≤ BATT ≤ 12V, TA= 0°C to +85°C

BATT = 12V, operating mode

1.8V ≤ BATT ≤ 20V, TA= +25°C

µA1

LCDON High, Leakage Current

mA-2 -6

LCDON Low, Sinking Current

-10 85

-20 10

FB Input Current (Note 3)

mV-8 0 8

V1.46 1.5 1.53

FB Regulation Voltage

mA-25DLO Output Current (Note 3)

mA50DHI Output Current (Note 3)

Ω

On-Resistance (DLO, DHI)

16.5 23.5

µs-V

Microsecond-Volt Time Constant (k-factor)

V27Positive Output Voltage

920

µA

150 250

VDDSupply Current

1.8 20BATT Operating Range (Note 2)

µA

13 20

LX Input Current

µA

BATT Input Current

-27Negative Output Voltage V1.5 2.8Undervoltage Lockout Threshold (Note 1)

13 20

V3.0 5.5VDDOperating Range

Voltage on POK rising V0.967 0.992 1.017POK Threshold Voltage

mV12POK Hysteresis

CONDITIONS UNITS

MIN TYP MAX

PARAMETER

No load V1.47 1.5 1.53REF Voltage 0µA ≤ I

REF

≤ 25mA mV310REF Load Regulation

SWITCHING REGULATOR

REFERENCE AND DAC OUTPUT

MAX1620/MAX1621

Digitally Adjustable LCD Bias Supplies

_______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VDD= 3.3V, V

BATT

= 10V, TA= 0°C to +85°C, unless otherwise noted.)

TIMING CHARACTERISTICS

(TA= 0°C to +85°C, unless otherwise noted.)

-20µA ≤ I

DOUT

≤ 0µA

SDA

= -6mA

VIN= 0V or VIN= V

VDD= 5.5V

3.0V ≤ VDD≤ 3.6V

48.39mV step size

VIN= 0V or VIN= V

Guaranteed monotonic

0µA ≤ I

DOUT

≤ 40µA

V0.4

µA±1

SCL, SDA, SUS Input Leakage Current

V0.6

SCL, SDA, SUS Input Low Voltage

2.3

1.4

SCL, SDA, SUS Input High Voltage

±1

0.6

V0 0.007DOUT Minimum Output Voltage (Note 3)

2.3

1.4

UP, DN, SHDN, POL Input High Voltage

LSBDOUT Differential Nonlinearity

Bits5DOUT Resolution

±1

REF - REF +

0.02 0.02

DOUT Maximum Output Voltage (Note 3) V

UP, DN, SHDN, POL Input Leakage Current

µA

UP, DN, SHDN, POL Input Low Voltage

SDA Output Low Voltage

CONDITIONS UNITSMIN TYP MAXPARAMETER

DIGITAL INPUTS AND OUTPUTS

(Note 4)

CONDITIONS

SCL Falling Edge to SDA Valid Master Clocking in Data

µst

µs4t

HD:STA

Start Condition SDA to SCL Hold Time

µs4.7t

SU:STA

Start Condition SCL to SDA Setup Time

µs4t

HIGH

SCL High Time

µs4.7t

LOW

SCL Low Time

ns300t

SCL/SDA Fall Time

µs1t

Pulse Width High (UP, DN)

µs1t

SCL/SDA Rise Time

ns0t

HD:DAT

SCL to SDA Data-Hold Time

ns500tSU:

DAT

SDA to SCL Data-Setup Time

µs1t

Pulse Width Low (UP, DN)

µs1t

Pulse Separation (UP, DN)

µs1t

Counter Reset Time

UNITSMIN TYP MAXSYMBOLPARAMETER

µs4t

SU:STO

Stop Condition SCL_ to SDA_ Setup Time

MAX1620 (Figure 1)

MAX1621 (Figures 2 and 3)

MAX1620/MAX1621

Digitally Adjustable LCD Bias Supplies

4 _______________________________________________________________________________________

Operating mode, output in regulation

µA

150 250

0µA ≤ I

REF

≤ 25µA

No load

REF Load Regulation

Voltage on POK rising

POL = VDD, 3.0V ≤ V

≤ 5.5V

FB = 0V - 50mV

3.0 5.5

4V ≤ BATT ≤ 12V

VDDOperating Range

FB = REF + 100mV

POL = AGND, 3.0V ≤ V

≤ 5.5V

mV510

V1.44 1.5 1.56REF Voltage

V27Positive Output Voltage

0.957 0.992 1.027

Shutdown mode, V

SHDN

= V

-10 120

FB Input Current (Note 3)

VDDSupply Current

-30 10

mV-10 0 10

V1.5 2.8Undervoltage Lockout Threshold (Note 1)

1.44 1.5 1.56

µs-VMicrosecond-Volt Time Constant (k-factor) 16 24

V1.8 20BATT Operating Range (Note 2)

-27Negative Output Voltage

FB Regulation Voltage

POK Threshold Voltage

DOUT Maximum Output Voltage (Note 3) V

REF - REF +

0.02 0.02

0µA ≤ I

DOUT

≤ 40µA

-20µA ≤ I

DOUT

≤ 0µADOUT Minimum Output Voltage (Note 3) V0 0.01

Guaranteed monotonicDOUT Differential Nonlinearity LSB±1

UP, DN, SHDN, POL Input High Voltage

3.0V ≤ VDD≤ 3.6V 1.4 VDD= 5.5V 2.3

UP, DN, SHDN, POL Input Low Voltage

0.6 V

3.0V ≤ VDD≤ 3.6V 1.4 VDD= 5.5V 2.3

SCL, SDA, SUS Input Low Voltage

0.6 V

SDA Output Low Voltage I

SDA

= -6mA 0.4 V

CONDITIONS UNITS

MIN TYP MAX

PARAMETER

ELECTRICAL CHARACTERISTICS

(VDD= 3.3V, V

BATT

= 10V, TA= -40°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted. Limits over this

temperature range are guaranteed by design.)

SCL, SDA, SUS Input High Voltage

SWITCHING REGULATOR

REFERENCE AND OUTPUT

DIGITAL INPUTS AND OUTPUTS

MAX1620/MAX1621

Digitally Adjustable LCD Bias Supplies

_______________________________________________________________________________________ 5

TIMING CHARACTERISTICS

(VDD= 3.3V, V

BATT

= 10V, TA= -40°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted. Limits over this

temperature range are guaranteed by design.)

CONDITIONS

Stop Condition SCL_ to SDA_ Setup Time

µst

SU:STO

µs4t

HD:STA

Start Condition SDA_ to SCL_ Hold Time

µs4.7t

SU:STA

Start Condition SCL_ to SDA_ Setup Time

µs4t

HIGH

SCL High Time

µs4.7t

LOW

SCL Low Time

ns300t

SCL/SDA Fall Time

µs1t

Pulse Width High (UP, DN)

µs1t

SCL/SDA Rise Time

ns0t

HD:DAT

SCL_ to SDA_ Data-Hold Time

ns500tSU:

DAT

SDA_ to SCL_ Data-Setup Time

µs1t

Pulse Width Low (UP, DN)

µs1t

Pulse Separation (UP, DN)

µs1t

Counter Reset Time

UNITSMIN TYP MAXSYMBOLPARAMETER

Note 1: The setting in the DAC is guaranteed to remain valid as long as VDDis greater than the UVLO threshold. Note 2: BATT Operating Range is guaranteed by the Microsecond-Volt Time Constant specification. Note 3: Current sourced from a pin is denoted as positive current. Current sunk into a pin is denoted as negative current. Note 4: Guaranteed by design.

__________________________________________Typical Operating Characteristics

(VDD= 5V, V

BATT

= 10V, L1 = 100µH, TA= +25°C, unless otherwise noted.)

0.70

0.75

0.80

0.85

0.90

0.95

1.00

010203040506070

EFFICIENCY vs. OUTPUT CURRENT

MAX1620/21-01

OUTPUT CURRENT (mA)

EFFICIENCY (%)

+25V

+15V

0.70

0.75

0.80

0.85

0.90

0.95

1.00

010203040506070

EFFICIENCY vs. OUTPUT CURRENT

MAX1620/21-02

OUTPUT CURRENT (mA)

EFFICIENCY (%)

-25V

-15V

0.70

0.75

0.80

0.85

0.90

0.95

1.00

12 14 16 18 20 22 24 26

EFFICIENCY vs. OUTPUT VOLTAGE

MAX1620/21-03

OUTPUT VOLTAGE (V)

EFFICIENCY (%)

+10mA

+20mA

SCL Falling Time to SDA Valid Master Clocking in Data

µst

MAX1620 (Figure 1)

MAX1621 (Figures 2 and 3)

MAX1620/MAX1621

Digitally Adjustable LCD Bias Supplies

6 _______________________________________________________________________________________

_____________________________Typical Operating Characteristics (continued)

5V, V

BATT

= 10V, L1 = 100µH, TA= +25°C, unless otherwise noted.)

0.70

0.75

0.80

0.85

0.90

0.95

1.00

-26 -24 -22 -20 -18 -16 -14 -12

EFFICIENCY vs. OUTPUT VOLTAGE

MAX1620/21-04

OUTPUT VOLTAGE (V)

EFFICIENCY (%)

-10mA

-20mA

0.70

0.75

0.80

0.85

0.90

0.95

1.00

2 4 6 8 10 12 14 16 18 20

EFFICIENCY vs. V

BATT

MAX1620/21-05

BATT

(V)

EFFICIENCY (%)

+20V, +10mA

-20V, -10mA

100

120

140

160

180

200

012345

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX1620/21-06

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (µA)

100

125

150

175

200

-40 -20 0 20 40 60 80

SUPPLY CURRENT vs. TEMPERATURE

MAX1620/21-07

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

1.49

1.50

1.51

-40 -20 0 20 40 60 80

REFERENCE VOLTAGE

vs. TEMPERATURE

MAX1620/21-10

TEMPERATURE (°C)

REFERENCE VOLTAGE (V)

012345

SHUTDOWN SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX1620/21-08

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (µA)

-40 -20 0 20 40 60 80

SHUTDOWN SUPPLY CURRENT

vs. TEMPERATURE

MAX1620/21-09

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

18.0

18.5

19.0

19.5

20.0

20.5

21.0

21.5

22.0

2.5 3.0 3.5 4.0 4.5 5.0

k-FACTOR vs. SUPPLY VOLTAGE

MAX1620/21-11

SUPPLY VOLTAGE (V)

k-FACTOR (µs-V)

18.0

18.5

19.0

19.5

20.0

20.5

21.0

21.5

22.0

-60 -40 -20 0 20 40 60 80 100

k-FACTOR vs. TEMPERATURE

MAX1620/21-12

TEMPERATURE (°C)

k-FACTOR (µs-V)

+ 14 hidden pages