interface. A low-drift, on-chip reference and 14-bit
ΔΣ
A/D
converter allow precise measurements of supply voltages,
load currents or internal die temperature. Fault manage-
ment allows
⎯
A
⎯
L
⎯
E
⎯
R
⎯
T to be asserted for configurable over
and under voltage fault conditions. Two voltage buffered,
8-bit IDACs allow highly accurate programming of DC/DC
converter output voltages. The IDACs can be configured
to automatically servo the power supplies to the desired
voltages using the ADC. The LTC2970-1 adds a tracking
feature that can be used to turn multiple power supplies
on or off in a controlled manner.
The bus address is set to 1 of 9 possible combinations by
pin strapping the ASEL0 and ASEL1 pins. The LTC2970/
LTC2970-1 are packaged in the 24-lead, 4mm
×
5mm
QFN package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
■
■
■
■
Less Than ±0.5% Total Unadjusted Error 14-Bit
ΔΣ
ADC with On-Chip Reference
Dual, 8-Bit IDACs with 1x Voltage Buffers
Linear, Voltage Servo Adjusts Supply Voltages by
Ramping IDAC Outputs Up/Down
I
2
C™ Bus Interface (SMBus Compatible)
Extensive, User Configurable Fault Monitoring
On-Chip Temperature Sensor
Available in 24-Lead 4mm
×
5mm QFN Package
APPLICATIO S
■
■
■
■
Dual Power Supply Voltage Servo
Monitoring Supply Voltage and Current
Programmable Power Supplies
Programmable Reference
TYPICAL APPLICATIO
Dual Power Supply Monitor and Controller (One of Two Channels Shown)
8V TO 15V
0.1μF
12V
IN
V
IN
IN
OUT
1/2 LTC2970
GPIO_CFG
I+
I–
DC/DC
CONVERTER
V
IN0_BM
V
IN0_BP
V
OUT0
V
IN0_AP
RUN/SS
FB
LOAD
I
OUT0
V
IN0_AM
ALERT
SCL
SDA
I
2
C BUS
SMBUS
COMPATIBLE
V
DD
ERROR (%)
0.1μF
0.25
(
)
GPIO_0
REF
0.1μF
GND
SGND
GND ASEL0 ASEL1
29701 TA01
U
U
U
ADC Total Unadjusted Error
vs Temperature
0.50
15 PARTS MOUNTED ON PCB
0
–0.25
–0.50
–50
ADC V
IN
= 5V
–25
50
25
TEMPERATURE (°C)
0
75
100
29701 TA01b
29701fc
1
LTC2970/LTC2970-1
ABSOLUTE
(Notes 1 and 2)
AXI U RATI GS
Supply Voltages:
V
DD
......................................................... –0.3V to 6V
12V
IN
.................................................... –0.3V to 15V
Digital Input/Output Voltages:
ASEL0, ASEL1 ............................ –0.3V to V
DD
+ 0.3V
SDA, SCL, GPIO_CFG,
⎯
A
⎯
L
⎯
E
⎯
R
⎯
T, GPIO_0, GPIO_1.......................... –0.3V to 6V
Analog Voltages:
V
IN0_AP
, V
IN0_AM
, V
IN0_BP
,
V
IN0_BM
, V
IN1_AP
, V
IN1_AM
,
V
IN1_BP
, V
IN1_BM
, V
OUT0
, V
OUT1
.............. –0.3V to 6V
I
OUT0
, I
OUT1
, REF......................... –0.3V to V
DD
+ 0.3V
RGND.................................................... –0.3V to 0.3V
Operating Temperature Range:
LTC2970C ................................................ 0°C to 70°C
LTC2970I ............................................. –40°C to 85°C
Storage Temperature Range...................– 65°C to 125°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
24 23 22 21 20
V
IN0_AP
1
V
IN0_AM
2
V
IN0_BP
3
V
IN0_BM
4
V
IN1_AP
5
V
IN1_AM
6
V
IN1_BP
7
8
V
IN1_BM
9 10 11 12
12V
IN
V
OUT0
V
OUT1
V
DD
25
19 SDA
18 SCL
17 ALERT
16 GPIO_0
15 GPIO_1
14 I
OUT0
13 I
OUT1
UFD PACKAGE
24-LEAD (4mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 37°C/W
EXPOSED PAD (PIN 25) IS GND MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC2970CUFD#PBF
LTC2970CUFD-1#PBF
LTC2970IUFD#PBF
LTC2970IUFD-1#PBF
TAPE AND REEL
LTC2970CUFD#TRPBF
LTC2970CUFD-1#TRPBF
LTC2970IUFD#TRPBF
LTC2970IUFD-1#TRPBF
PART MARKING*
2970
29701
2970
29701
PACKAGE DESCRIPTION
24-Lead (4mm
×
5mm) Plastic DFN
24-Lead (4mm
×
5mm) Plastic DFN
24-Lead (4mm
×
5mm) Plastic DFN
24-Lead (4mm
×
5mm) Plastic DFN
TEMPERATURE RANGE
0°C to 70°C
0°C to 70°C
–40°C to 85°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
GPIO_CFG
ASEL0
ASEL1
RGND
REF
2
U
W W
W
PIN CONFIGURATION
TOP VIEW
29701fc
LTC2970/LTC2970-1
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
12VIN
= 12V, V
DD
and REF pins floating unless otherwise indicated,
C
VDD
= 100nF and C
REF
= 100nF.
SYMBOL
I
V12
I
DD
V
LKO
V
DD
PARAMETER
12V
IN
Supply Current
V
DD
Supply Current
V
DD
Undervoltage Lockout
V
DD
Undervoltage Lockout Hysteresis
Supply Input Operating Range
Regulator Output Voltage
Regulator Output Voltage
Temperature Coefficient
Regulator Output Voltage Load
Regulation
Regulator Line Regulation
V
12VIN
V
REF
12V
IN
Supply Operating Range
Reference Output Voltage
Reference Voltage Temperature
Coefficient
Reference Overdrive Voltage Input
Range
ADC Characteristics
N_ADC
TUE_ADC
INL_ADC
DNL_ADC
V
IN_ADC
V
OS_ADC
GAIN_ADC
T
CONV_ADC
C
IN_ADC
F
IN_ADC
I
LEAK_ADC
N_I
OUT
INL_I
OUT
DNL_I
OUT
I
FS-
I
OUT
I
DRIFT-
I
OUT
I
OS-
I
OUT
Resolution
Total Unadjusted Error
Integral Nonlinearity
Differential Nonlinearity
Input Voltage Range
Offset Error
Offset Error Drift
Gain Error
Gain Error Drift
Conversion Time
Input Sampling Capacitance
Input Sampling Frequency
Input Leakage Current
Resolution (Guaranteed Monotonic)
Integral Nonlinearity
Differential Nonlinearity
Full-Scale Output Current
Output Current Drift
Offset Current
V
IOUTn
< V
DD
– 1.5V
V
IOUTn
< V
DD
– 1.5V
V
IOUTn
< V
DD
– 1.5V, DAC Code = 'hff
DAC Code = 'hff
DAC Code = 'h00
●
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
CONDITIONS
V
12VIN
= 12V, V
DD
Floating
V
DD
= 5V, V
12VIN
= V
DD
V
DD
Ramping-Down, V
12VIN
= V
DD
●
●
●
MIN
TYP
4.24
3.7
MAX
7.5
5
4.4
5.75
UNITS
mA
mA
V
mV
V
V
ppm/°C
ppm/mA
ppm/V
Power-Supply Characteristics
3.7
4.5
4.75
4.14
118
8V ≤ V
12VIN
≤ 15V, –1mA ≤ I
VDD
≤ 0
●
4.95
10
5.25
–1mA ≤ I
VDD
≤ 0
8V ≤ V
12VIN
≤ 15V, I
VDD
= 0mA
●
●
160
80
–5
8
1.229
2
1
1.5
–34
–63
15
Regulator Output Short-Circuit Current V
12VIN
= 12V, V
DD
= 0V
Voltage Reference Characteristics
mA
V
V
ppm/°C
V
N_ADC = 8.192V/16384
V
IN
= 3V, V
IN
= V
INn_xP
– V
INn_xM
(Note 3)
(Note 4)
(Note 7)
●
●
●
●
●
500
±0.5
–4.5
0
–1000
–316
0.19
2
4.5
±0.5
6
1000
±0.4
3
33.3
3
61.4
μV/LSB
%
LSB
LSB
V
μV
μV/°C
%
ppm/°C
ms
pF
kHz
±0.1
μA
Bits
±1
±1
LSB
LSB
μA
ppm/°C
±0.1
μA
29701fc
Full-Scale V
IN
= 6V
●
0V < V
IN
< 6V
●
IDAC Output Current Characteristics
8
–236
–255
32
–276
3
LTC2970/LTC2970-1
ELECTRICAL CHARACTERISTICS
SYMBOL
INL_V
OUT
DNL_V
OUT
V
OS-
V
OUT
V
OUT
PARAMETER
Integral Nonlinearity
Differential Nonlinearity
Offset Voltage
Output Voltage Drift
Load Regulation
Leakage Current
Short-Circuit Current Low
Short-Circuit Current High
V
OS
TMP
GAIN_12V
IN
V
IH
V
IL
V
HYST
I
LEAK
C
IN
V
IH_ASEL
V
IL_ASEL
I
IN,HL
I
IN,Z
V
OL
I
OH
Offset Voltage
Gain
Gain
Input High Threshold Voltage
Input Low Threshold Voltage
Input Hysteresis
Input Leakage Current
Input Capacitance
Input High Threshold Voltage
Input Low Threshold Voltage
High, Low Input Current
High Z Input Current
Output Low Voltage
Input Leakage Current
I
SINK
= 3mA
0V ≤ V
IN
≤ 6V
ASEL[1:0] = 0, V
DD
●
●
●
●
●
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
随着阅读器与标签价格的降低和全球市场的扩大，射频标识 RFID(以下简称RFID)的应用与日俱增。标签既可由阅读器供电(无源标签)，也可以由标签的板上电源供电(半有源标签和有源标签)。由于亚微型无源 CMOS 标签的成本降低，库存和其他应用迅速增加。一些评估表明，随着无源标签的价格持续下降，几乎每一个售出产品的内部都将有一个 RFID 标签。由于无源 RFID 标签的重要性及其独特的工程实现...[详细]
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