OMO ElectronicOMO Electronic
Expand menu
Hello, Sign inMy Account
0 Cart

LTC3717EUH-1#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
1
LTC3717-1
sn37171 37171fs
Wide Operating Range,
No R
SENSE
TM
Step-Down Controller
for DDR/QDR Memory Termination
■
V
OUT
= 1/2 V
REF
■
Adjustable and Symmetrical Sink/Source
Current Limit up to 20A
■
True Current Mode Control with Optional Use of
Sense Resistor
■
V
ON
and I
ON
Pins Allow Constant Frequency
Operation During Input and Output Voltage Changes
■
±0.65% Output Voltage Accuracy
■
Up to 97% Efficiency
■
Ultrafast Transient Response
■
2% to 90% Duty Cycle at 200kHz
■
t
ON(MIN)
≤ 100ns
■
Stable with Ceramic C
OUT
■
Power Good Output Voltage Monitor
■
Wide V
IN
Range: 4V to 36V
■
Adjustable Switching Frequency up to 1.5MHz
■
Output Overvoltage Protection
■
Optional Short-Circuit Shutdown Timer
■
Available in a 5mm × 5mm QFN Package
■
Bus Termination: DDR and QDR Memory, SSTL,
HSTL, ...
■
Notebook Computers, Desktop Servers
■
Tracking/Margining Power Supply
The LTC
®
3717-1 is a synchronous step-down switching
regulator controller for double data rate (DDR) and Quad
Data Rate
TM
(QDR
TM
) memory termination. The controller
uses a valley current control architecture to deliver very
low duty cycles with or without a sense resistor. Operating
frequency is selected by an external resistor and is com-
pensated for variations in V
IN
and V
OUT
.
Forced continuous operation reduces noise and RF inter-
ference. Output voltage is internally set to half of V
REF
,
which is user programmable.
Fault protection is provided by an output overvoltage
comparator and optional short-circuit shutdown timer.
Soft-start capability for supply sequencing is accom-
plished using an external timing capacitor. The regulator
current limit level is symmetrical and user programmable.
Wide supply range allows operation from 4V to 36V at the
V
CC
input.
, LTC and LT are registered trademarks of Linear Technology Corporation.
No R
SENSE
is a trademark of Linear Technology Corporation.
QDR RAMs and Quad Data Rate RAMs comprise a new family of products developed by Cypress
Semiconductor, Hitachi, IDT, Micron Technology, Inc. and Samsung.
Figure 1. High Efficiency DDR Memory Termination Supply
Efficiency vs Load Current
+
CMDSH-3
B320A
0.68µH
4.7µF
150µF
6.3V
×2
V
IN
2.5V TO 5.5V
V
OUT
1.25V
±10A
+
+
180µF
4V
×2
Si7840DP
37171 F01a
Si7840DP
715k
0.1µF
I
ON
V
REF
TG
SW
DRV
CC
SENSE
+
SENSE
–
BOOST
RUN/SS
I
TH
SGND
INTV
CC
BGV
ON
PGND
V
FB
PGOOD
0.22µF
20k
LTC3717-1
470pF
1µF
V
CC
V
CC
5V TO 28V
B320A
V
DD
= 2.5V
LOAD CURRENT (A)
0
EFFICIENCY (%)
37171 F01b
100
90
80
70
60
50
40
30
20
10
0
2 4 6 8 10 12 14
V
IN
= 2.5V
V
IN
= 5V
V
OUT
= 1.25V
APPLICATIO S
U
FEATURES
TYPICAL APPLICATIO
U
DESCRIPTIO
U
2
LTC3717-1
sn37171 37171fs
ORDER PART NUMBER
Consult LTC Marketing for parts specified with wider operating temperature ranges.
T
JMAX
= 125°C, θ
JA
= 34°C/W
EXPOSED PAD IS SGND (PIN 33) MUST BE SOLDERED TO PCB
ABSOLUTE AXI U RATI GS
WWWU
PACKAGE/ORDER I FOR ATIO
UU
W
QFN PART MARKING
32 31 30 29 28 27 26 25
9 10 11 12
TOP VIEW
UH PACKAGE
32-LEAD (5mm × 5mm) PLASTIC QFN
13 14 15 16
17
18
19
20
21
22
23
24
8
7
6
5
4
3
2
1V
ON
PGOOD
V
RNG
I
TH
SGND
I
ON
V
FB
NC
SW
SENSE
+
NC
SENSE
–
PGND
BG
DRV
CC
INTV
CC
NC
RUN/SS
NC
NC
BOOST
TG
NC
NC
NC
V
REF
NC
NC
NC
NC
EXTV
CC
V
IN
33
LTC3717EUH-1 37171
(Note 1)
Boosted Topside Driver Supply Voltage
(BOOST) ............................................... 42V to –0.3V
V
IN
, I
ON
, SW, SENSE
+
Voltage .................. 36V to –0.3V
EXTV
CC
, DRV
CC
, RUN/SS, PGOOD,
(BOOST – SW) Voltages ............................ 7V to –0.3V
V
ON
, V
REF
, V
RNG
Voltages .......(INTV
CC
+ 0.3V) to –0.3V
I
TH
, V
FB
Voltages...................................... 2.7V to –0.3V
TG, BG, INTV
CC
, EXTV
CC
, DRV
CC
Peak Currents ....... 2A
TG, BG, INTV
CC
, EXTV
CC
, DRV
CC
RMS Currents.. 50mA
Operating Ambient Temperature
Range (Note 4) ................................... –40°C to 85°C
Junction Temperature (Note 2)............................ 125°C
Storage Temperature Range ................. –65°C to 125°C
Reflow Peak Body Temperature............................260°C
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are T
A
= 25°C. V
IN
= 15V, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Buck Regulator
I
Q(VIN)
Input DC Supply Current (V
IN
)
Normal 1000 2000 µA
Shutdown Supply Current V
RUN/SS
= 0V 15 30 µA
V
FB
Feedback Voltage Accuracy I
TH
= 1.2V (Note 3), V
REF
= 2.4V ● –0.65 0.1 0.65 %
∆V
FB(LINE)
Feedback Voltage Line Regulation V
IN
= 4V to 36V, I
TH
= 1.2V (Note 3) 0.002 %/V
∆V
FB(LOAD)
Feedback Voltage Load Regulation I
TH
= 0.5V to 1.9V (Note 3) ● –0.05 –0.3 %
g
m(EA)
Error Amplifier Transconductance I
TH
= 1.2V (Note 3) 0.93 1.13 1.33 mS
t
ON
On-Time I
ON
= 30µA, V
ON
= 0V 186 233 280 ns
I
ON
= 60µA, V
ON
= 0V 95 115 135 ns
t
ON(MIN)
Minimum On-Time I
ON
= 180µA 50 100 ns
t
OFF(MIN)
Minimum Off-Time 300 400 ns
V
SENSE(MAX)
Maximum Current Sense Threshold V
RNG
= 1V, V
FB
= V
REF
/2 – 50mV ● 108 135 162 mV
V
PGND
– V
SW
(Source) V
RNG
= 0V, V
FB
= V
REF
/2 – 50mV ● 76 95 114 mV
V
RNG
= INTV
CC
, V
FB
= V
REF
/2 – 50mV ● 148 185 222 mV
V
SENSE(MIN)
Minimum Current Sense Threshold V
RNG
= 1V, V
FB
= V
REF
/2 + 50mV ● –140 –165 –190 mV
V
PGND
– V
SW
(Sink) V
RNG
= 0V, V
FB
= V
REF
/2 + 50mV ● –97 –115 –133 mV
V
RNG
= INTV
CC
, V
FB
= V
REF
/2 + 50mV ● –200 –235 – 270 mV
3
LTC3717-1
sn37171 37171fs
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are T
A
= 25°C. V
IN
= 15V, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
∆V
FB(OV)
Output Overvoltage Fault Threshold 8 10 12 %
V
FB(UV)
Output Undervoltage Threshold –25 %
V
RUN/SS(ON)
RUN Pin Start Threshold ● 0.8 1.5 2 V
V
RUN/SS(LE)
RUN Pin Latchoff Enable RUN/SS Pin Rising 4 4.5 V
V
RUN/SS(LT)
RUN Pin Latchoff Threshold RUN/SS Pin Falling 3.5 4.2 V
I
RUN/SS(C)
Soft-Start Charge Current V
RUN/SS
= 0V –0.5 –1.2 –3 µA
I
RUN/SS(D)
Soft-Start Discharge Current V
RUN/SS
= 4.5V, V
FB
= 0V 0.8 1.8 3 µA
V
IN(UVLO)
V
IN
Undervoltage Lockout V
IN
Falling ● 3.4 3.9 V
V
IN
Rising ● 3.5 4.0 V
TG R
UP
TG Driver Pull-Up On Resistance TG High (Note 5) 2 Ω
TG R
DOWN
TG Driver Pull-Down On Resistance TG Low (Note 5) 2 Ω
BG R
UP
BG Driver Pull-Up On Resistance BG High (Note 5) 3 Ω
BG R
DOWN
BG Driver Pull-Down On Resistance BG Low (Note 5) 1 Ω
TG t
r
TG Rise Time C
LOAD
= 3300pF 20 ns
TG t
f
TG Fall Time C
LOAD
= 3300pF 20 ns
BG t
r
BG Rise Time C
LOAD
= 3300pF 20 ns
BG t
f
BG Fall Time C
LOAD
= 3300pF 20 ns
Internal V
CC
Regulator
V
INTVCC
Internal V
CC
Voltage 6V < V
CC
< 30V, V
EXTVCC
= 4V ● 4.7 5 5.3 V
∆V
LDO(LOADREG)
Internal V
CC
Load Regulation I
CC
= 0mA to 20mA, V
EXTVCC
= 4V –0.1 ±2%
V
EXTVCC
EXTV
CC
Switchover Voltage I
CC
= 20mA, V
EXTVCC
Rising ● 4.5 4.7 V
∆V
EXTVCC
EXTV
CC
Switch Drop Voltage I
CC
= 20mA, V
EXTVCC
= 5V 150 300 mV
∆V
EXTVCC(HYS)
EXTV
CC
Switchover Hysteresis 200 mV
PGOOD Output
∆V
FBH
PGOOD Upper Threshold V
FB
Rising (0% = 1/3 V
REF
) 8 10 12 %
∆V
FBL
PGOOD Lower Threshold V
FB
Falling (0% = 1/3 V
REF
)–8–10–12%
∆V
FB(HYS)
PGOOD Hysteresis V
FB
Returning (0% = 1/3 V
REF
)12%
V
PGL
PGOOD Low Voltage I
PGOOD
= 5mA 0.15 0.4 V
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
as follows:
LTC3717EUH-1: T
J
= T
A
+ (P
D
• 34°C/W)
Note 3: The LTC3717EUH-1 is tested in a feedback loop that adjusts V
FB
to
achieve a specified error amplifier output voltage (I
TH
).
Note 4: The LTC3717EUH-1 is guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 5: R
DS(ON)
limit guaranteed by design and/or correlation to static
test.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

LTC3717EUH-1#TRPBF

Mfr. #:
Buy LTC3717EUH-1#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Power Supply for DDR in QFN
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet