LTC3720 Datasheet, PDF (3/24 Pages) Linear Technology – Single Phase VRM8.5 Current Mode Step-Down Controller

LTC3720
ELECTRICAL CHARACTERISTICS _{The q denotes specifications which apply over the full operating}
temperature range, otherwise specifications are T_A = 25°C. V_IN = 15V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX
V_RUN/SS(LE)
V_RUN/SS(LT)
I_RUN/SS(C)
I_RUN/SS(D)
V_IN (UVLO)
RUN Pin Latchoff Enable Threshold
RUN Pin Latchoff Threshold
Soft-Start Charge Current
Soft-Start Discharge Current
Undervoltage Lockout
TG R_UP
TG Driver Pull-Up On Resistance
TG R_DOWN
TG Driver Pull-Down On Resistance
BG R_UP
BG Driver Pull-Up On Resistance
BG R_DOWN
BG Driver Pull-Down On Resistance
TG t_r
TG Rise Time
TG t_f
TG Fall Time
BG t_r
BG Rise Time
BG t_f
BG Fall Time
Internal V_CC Regulator
V_INTVCC
Internal V_CC Voltage
∆V_LDO(LOADREG) Internal V_CC Load Regulation
V_EXTVCC
EXTV_CC Switchover Voltage
∆V_EXTVCC
EXTV_CC Switch Drop Voltage
∆V_EXTVCC(HYS) EXTV_CC Switchover Hysteresis
PGOOD Output
RUN/SS Pin Rising
RUN/SS Pin Falling
V_IN Falling
V_IN Rising
TG High
TG Low
BG High
BG Low
C_LOAD = 3300pF
C_LOAD = 3300pF
C_LOAD = 3300pF
C_LOAD = 3300pF
6V < V_IN < 30V, V_EXTVCC = 4V
I_CC = 0mA to 20mA, V_EXTVCC = 4V
I_CC = 20mA, V_EXTVCC Rising
I_CC = 20mA, V_EXTVCC = 5V
4
4.5
3.5
– 0.5 – 1.2
–3
0.8
1.8
3
q
3.4
3.9
q
3.5
4.0
2
3
2
3
3
4
1
2
20
20
20
20
q 4.7
5
5.3
– 0.1
±2
q 4.5
4.7
150 300
200
∆V_FBH
∆V_FBL
∆V_FB(HYS)
V_PGL
VID DAC
PGOOD Upper Threshold
PGOOD Lower Threshold
PGOOD Hysteresis
PGOOD Low Voltage
V_FB Rising
V_FB Falling
V_FB Returning
I_PGOOD = 5mA
5.5
7.5
9.5
– 5.5 – 7.5 – 9.5
1
2
0.15
0.4
V_CC
V_VID(T)
V_VID(LEAK)
∆V_OSENSE
R_PULLUP
R_VID
I_VCC
Operating Supply Voltage Range
VID0-VID4 Logic Threshold Voltage
VID0-VID4 Leakage Current
DAC Output Accuracy
Pull-Up Resistance on VID
Resistance from V_OSENSE to V_FB
Supply Current
V_CC = 3.3V
V_VID0-V_VID4 = V_CC
V_OSENSE Programmed from
1.05V to 1.825V (Note 5), V_CC = 5V
V_DIODE = 0.6V (Note 6)
(Note 7)
3.1
5.5
0.4
1.2
2
0.01
±1
– 0.25
0
0.25
28
40
56
6
10
14
1
10
UNITS
V
V
µA
µA
V
V
Ω
Ω
Ω
Ω
ns
ns
ns
ns
V
%
V
mV
mV
%
%
%
V
V
V
µA
%
kΩ
kΩ
µA
Note 1: Absolute Maximum Ratings are those values beyond which the life of
a device may be impaired.
Note 2: The LTC3720E 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 3: T_J is calculated from the ambient temperature T_A and power
dissipation P_D as follows:
LTC3720EGN: T_J = T_A + (P_D • 95°C/W)
Note 4: The LTC3720 is tested in a feedback loop that adjusts V_FB to achieve
a specified error amplifier output voltage (I_TH).
Note 5: The LTC3720 VID DAC is tested in a feedback loop that adjusts
V_OSENSE to achieve a specified feedback voltage (V_FB = 0.8V) for each DAC VID
code.
Note 6: Each built-in pull-up resistor attached to VID inputs also has a series
diode connected to V_CC to allow input voltages higher than the V_CC supply
without damage or clamping. (See Operation section for further details.)
Note 7: Supply current is specified with all VID inputs floating. Due to the
internal pull-ups on the VID pins, the supply current will increase depending
on the number of grounded VID lines. Each grounded VID line will draw
approximately (V_CC – 0.6V)/40k mA. (See Operation section for further
details.)
3720f
3