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LTC1426CS8#TRPBF

P1-P3P4-P6P7-P8
1
LTC1426
Micropower
Dual 6-Bit PWM DAC
FEATURES
DESCRIPTION
U
■
Wide Supply Range: 2.7V ≤ V
CC
≤ 5.5V
■
Wide Reference Voltage Range: 0V to 5.5V
■
Two Interface Modes:
Pulse Mode (Increment Only)
Pushbutton Mode (Increment/Decrement)
■
Low Supply Current: 50µA
■
0.2µA Supply Current in Shutdown
■
Available in 8-Pin MSOP and SO Packages
■
DAC Contents Are Retained in Shutdown
■
DACs Power-Up at Midrange
■
Low Output Impedance: <100Ω
■
Output Frequency: 5kHz Typ
The LTC
®
1426 is a dual micropower 6-bit PWM DAC
featuring versatile PWM outputs and a flexible pushbutton
compatible digital interface. The DAC outputs provide a
PWM signal that swings from 0V to V
REF
, allowing the full-
scale output to be varied by adjusting the voltage at V
REF
.
The PWM output frequency is typically 5kHz, easing
output filtering requirements. V
CC
supply current is typi-
cally 50µA and drops to 0.2µA in shutdown.
The LTC1426 can be controlled using one of two interface
modes: pushbutton and pulse. The LTC1426 automati-
cally configures itself into the appropriate mode at start-
up by monitoring the state of the CLK pins. In pushbutton
mode, the CLK pins can be directly connected to external
pushbuttons to control the DAC output. In pulse mode,
the CLK pins can be connected to CMOS compatible
logic. The DAC outputs initially power up at half scale and
the contents of the internal DAC registers are retained in
shutdown.
The LTC1426 is available in 8-pin MSOP and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
■
LCD Contrast and Backlight Brightness Control
■
Power Supply Voltage Adjustment
■
Battery Charger Voltage and Current Adjustment
■
GaAs FET Bias Adjustment
■
Trimmer Pot Elimination
APPLICATIONS
U
TYPICAL APPLICATION
U
Pushbutton Adjustable CCFL/LCD Contrast Generator
1
2
3
4
8
7
6
5
CLK1
CLK2
GND
PWM1
SHDN
V
CC
V
REF
PWM2
LTC1426
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
CCFL PGND
I
CCFL
DIO
CCFL V
C
AGND
SHDN
LCD V
C
LCD PGND
CCFL V
SW
BULB
BAT
ROYER
V
IN
FBP
FBN
LCD V
SW
LT1182
1426 TA01
C4
0.1µF
5V
DOWN
CONTRAST
UP/DOWN
CCFL UP/DOWN
DOWN
UP UP
R
P1
47k
R
P2
47k
R
SHDN
1M
SHDN
R5
20k
1%
R6
40k
1%
R4
4.99k
1%
R3
5.1k
1%
R1
44.2k
1%
R2
44.2k
1%
UP TO 6mA
I
CCFL
= 0µA TO 50µA
C3
10µF
C9
2.2µF
5V
CONSULT THE LT1182 DATA SHEET FOR 
DETAILS ON THE HIGH VOLTAGE ROYER 
AND LCD CONTRAST CONVERTER SECTIONS
C2
1µF
C10
2.2µF
35V
8V TO 
28V
C1
0.1µF
C8
0.68µF
C7 1µF
R7
10k
HIGH VOLTAGE
ROYER
LAMP
LCD
CONTRAST
CONVERTER
V
OUT
NEGATIVE
LCD CONTRAST
V
OUT
= –10V TO –30V
+
C11
2.2µF
35V
+
2
LTC1426
ABSOLUTE MAXIMUM RATINGS
W
WW
U
PACKAGE/ORDER INFORMATION
W
U
U
(Note 1)
Total Supply Voltage (V
CC
) ........................................ 7V
Reference Voltage (V
REF
)............................... –0.3 to 7V
Input Voltage (All Inputs) ..............– 0.3 to (V
CC
+ 0.3V)
DAC Output Short-Circuit Duration.................. Indefinite
I
PWM(MAX)
.......................................................... 100mA
Operating Temperature Range
LTC1426C................................................ 0°C to 70°C
LTC1426I........................................... –40°C to 85°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)..................300°C
ORDER PART
NUMBER
MS8 PART MARKING
LTC1426CMS8
LTC1426CS8
LTC1426IS8
S8 PART MARKING
1426
1426I
LTBQ
1
2
3
4
8
7
6
5
TOP VIEW
S8 PACKAGE
8-LEAD PLASTIC SO
MS8 PACKAGE
8-LEAD PLASTIC MSOP
CLK1
CLK2
GND
PWM1
SHDN
V
CC
V
REF
PWM2
T
JMAX
= 100°C, θ
JA
= 200°C/ W (MS8)
T
JMAX
= 100°C, θ
JA
= 130°C/ W (S8)
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
T
A
= 25°C, (Note 2) unless otherwise specified.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
CC
Supply Voltage ● 2.7 5.5 V
V
REF
Reference Voltage ● 0 5.5 V
I
CC
Supply Current Pulse Mode: V
SHDN
= V
CC
, V
CLK1
= V
CLK2
= 0V, PWM1 = PWM2 = NC ● 40 100 µA
Pushbutton Mode: V
SHDN
= V
CC
, V
CLK1
= V
CLK2
= PWM1 = PWM2 = NC ● 50 100 µA
SHDN = 0 (Note 3)
● 0.2 ±10 µA
I
REF
Reference Current Pulse Mode: V
SHDN
= V
CC
, V
CLK1
= V
CLK2
= 0V, PWM1 = PWM2 = NC ● 75 150 µA
Pushbutton Mode: V
SHDN
= V
CC
, V
CLK1
= V
CLK2
= PWM1 = PWM2 = NC ● 75 150 µA
SHDN = 0 (Note 3)
● 0.2 ±10 µA
DAC Resolution 6 bits
DAC Frequency 0°C ≤ T
A
≤ 70°C ● 356 kHz
–40°C ≤ T
A
≤ 85°C ● 256 kHz
DAC Output Impedance V
CC
= 2.7V, V
REF
= 0.5V ● 20 100 Ω
DAC Full-Scale Duty Cycle 98.44 %
DAC Zero-Scale Duty Cycle 0%
DNL DAC Differential Nonlinearity Monotonicity Guaranteed (Note 4) ● ±0.05 LSB
INL DAC Integral Nonlinearity (Note 4) ● ±0.05 LSB
FS Error DAC Full-Scale Error ● ±0.50 LSB
I
IN
Logic Input Current Pulse Mode: 0V ≤ V
IN
≤ V
CC
SHDN ● ±5 µA
CLK1, CLK2
● ±5 µA
Pushbutton Mode: 0V ≤ V
IN
≤ V
CC
SHDN ● ±5 µA
CLK1, CLK2
● ±10 µA
V
IH
CLK High Level V
CC
= 5.5V SHDN ● 2.0 V
Input Voltage (Note 5) CLK1, CLK2
● 4.4 V
V
CC
= 3.6V SHDN ● 1.9 V
CLK1, CLK2
● 2.9 V
3
LTC1426
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IL
CLK Low Level V
CC
= 4.5V SHDN ● 0.8 V
Input Voltage (Note 5) CLK1, CLK2
● 0.8 V
V
CC
= 2.7V SHDN ● 0.45 V
CLK1, CLK2
● 0.45 V
I
OZ
Three-State Output Leakage SHDN = 0 ● ±5 µA
Z
IN
CLK Input Resistance Pushbutton Mode, CLK1/CLK2 2.5 MΩ
f
CLK
Clock Frequency Pulse Mode, V
CC
= 3.3V ● 1 MHz
Pulse Mode, V
CC
= 2.7V ● 750 kHz
t
CKHI
Clock High Time Pulse Mode, V
CC
= 3.3V ● 450 ns
Pulse Mode, V
CC
= 2.7V ● 600 ns
t
CKLO
Clock Low Time Pulse Mode, V
CC
= 3.3V ● 450 ns
Pulse Mode, V
CC
= 2.7V ● 600 ns
t
PW
Pulse Width Pushbutton Mode ● 670 µs
t
DEB
Debounce Time Pushbutton Mode ● 10.7 12.8 21.3 ms
t
DELAY
Repeat Rate Delay Pushbutton Mode ● 340 410 680 ms
f
REPEAT
Repeat Frequency Pushbutton Mode ● 11.7 19.5 23.4 Hz
ELECTRICAL CHARACTERISTICS
T
A
= 25°C, (Note 2) unless otherwise specified.
Note 3: Shutdown current can be negative due to leakage currents if V
CC
>
V
REF
or V
REF
> V
CC
.
Note 4: Guaranteed by Design. Decouple the V
CC
and V
REF
pins to GND
using high quality, low ESR, low ESL 0.1µF capacitors to eliminate PWM
switching noise that may otherwise get coupled into the CLK1/CLK2 high
impedance input buffers. The decoupling capacitors should be located in
close proximity to these pins and the ground line to have maximum effect.
Note 5: Input thresholds apply for both pushbutton and pulse modes.
The
● denotes the specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground, unless otherwise
specified. All typicals are given for V
CC
= V
REF
= 5V, T
A
= 25°C and
PWM1/PWM2 output to GND, C
PWM
= 10pF.
TYPICAL PERFORMANCE CHARACTERISTICS
U
W
CODE
0
–0.05
DNL ERROR (LSB)
–0.04
–0.02
–0.01
0
0.05
0.02
16
32
40
1426 G01
–0.03
0.03
0.04
0.01
824
48
56
64
V
CC
= V
REF
= 5V
T
A
= 25°C
CODE
0
–0.05
ERROR (LSB)
–0.04
–0.02
–0.01
0
0.05
0.02
16
32
40
1426 G02
–0.03
0.03
0.04
0.01
824
48
56
64
V
CC
= V
REF
= 5V
T
A
= 25°C
OUTPUT CURRENT SINK CAPABILITY (mA)
1
OUTPUT PULL-DOWN VOLTAGE (mV)
100
1000
0.1 10 100
1426 G03
0.1
1
10
85°C
–40°C
V
CC
= 5V
25°C
Output Pull-Down Voltage
vs Output Current Sink Capability
Integral Nonlinearity (INL)
Differential Nonlinearity (DNL)
P1-P3P4-P6P7-P8

LTC1426CS8#TRPBF

Mfr. #:
Buy LTC1426CS8#TRPBF
Manufacturer:
Analog Devices Inc.
Description:
Digital to Analog Converters - DAC uP 2x 6-B PWM DAC
Lifecycle:
New from this manufacturer.
Delivery:
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