Datasheet LTC3736-1 (Analog Devices) - 6
| Manufacturer | Analog Devices |
| Description | Dual 2-Phase, No RSENSE , Synchronous Controller with Spread Spectrum |
| Pages / Page | 28 / 6 — TYPICAL PERFOR A CE CHARACTERISTICS TA = 25. C unless otherwise noted. … |
| File Format / Size | PDF / 541 Kb |
| Document Language | English |
TYPICAL PERFOR A CE CHARACTERISTICS TA = 25. C unless otherwise noted. Shutdown Quiescent Current. RUN/SS Start-Up Current
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LTC3736-1
W U TYPICAL PERFOR A CE CHARACTERISTICS TA = 25
°
C unless otherwise noted. Shutdown Quiescent Current RUN/SS Start-Up Current vs Input Voltage vs Input Voltage
20 0.9 RUN/SS = 0V RUN/SS = 0V 18 A) 0.8 µ 16 A) 0.7 µ 14 0.6 12 0.5 10 0.4 8 6 0.3 SHUTDOWN CURRENT ( 4 0.2 2 RUN/SS PIN PULL-UP CURRENT ( 0.1 0 0 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 37361 G17 37361 G18
U U U PI FU CTIO S (UF/GN Package) ITH1/ITH2 (Pins 1, 8/Pins 4, 11):
Current Threshold and R = 10Ω, C = 1µF) is suggested to minimize noise pickup, Error Amplifier Compensation Point. Nominal operating especially in high load current applications. range on these pins is from 0.7V to 2V. The voltage on
TRACK (Pin 6/Pin 9):
Tracking Input for Second Control- these pins determines the threshold of the main current ler. Allows the start-up of VOUT2 to “track” that of VOUT1 comparator. according to a ratio established by a resistor divider on
FREQ (Pin 3/Pin 6):
Frequency Filter and Adjust Pin. Nor- VOUT1 connected to the TRACK pin. For one-to-one track- mally, when spread spectrum operation is enabled (SSDIS ing of VOUT1 and VOUT2 during start-up, a resistor divider = GND), a capacitor (1nF to 4.7nF) is connected from this with a ratio equal to those connected to VFB2 from VOUT2 pin to SGND or VIN to filter and smooth the changes in fre- should be used to connect to TRACK from VOUT1. quency of the LTC3736-1’s internal oscillator.
PGOOD(Pin 9/Pin 12):
Power Good Output Voltage Moni- When spread spectrum operation is disabled (SSDIS = VIN), tor Open-Drain Logic Output. This pin is pulled to ground this pin serves as a frequency adjust pin. In this mode, tying when the voltage on either feedback pin (VFB1, VFB2) is not this pin to GND selects 300kHz operation; tying this pin to within ±13.3% of its nominal set point. VIN selects 750kHz operation; floating this pin selects
PGND (Pins 12, 16, 20, 25/Pins 15, 19, 23):
Power Ground. 550kHz operation. These pins serve as the ground connection for the gate When spread spectrum operation is enabled (SSDIS = drivers and the negative input to the reverse current com- GND), an external voltage between approximately 0.7V and parators. The Exposed Pad (UF package) must be soldered 1.5V may be applied to this pin to adjust (in an analog to PCB ground. manner) the LTC3736-1’s frequency.
RUN/SS (Pin 14/Pin 17):
Run Control Input and Optional
SGND (Pin 4/Pin 7):
Small-Signal Ground. This pin serves External Soft-Start Input. Forcing this pin below 0.65V shuts as the ground connection for most internal circuits. down the chip (both channels). Driving this pin to VIN or
V
releasing this pin enables the chip, using the chip’s inter-
IN (Pin 5/Pin 8):
Chip Signal Power Supply. This pin powers the entire chip except for the gate drivers. Externally nal soft-start. An external soft-start can be programmed by filtering this pin with a lowpass RC network (e.g., connecting a capacitor between this pin and ground. 37361f 6
W U TYPICAL PERFOR A CE CHARACTERISTICS TA = 25
°
C unless otherwise noted. Shutdown Quiescent Current RUN/SS Start-Up Current vs Input Voltage vs Input Voltage
20 0.9 RUN/SS = 0V RUN/SS = 0V 18 A) 0.8 µ 16 A) 0.7 µ 14 0.6 12 0.5 10 0.4 8 6 0.3 SHUTDOWN CURRENT ( 4 0.2 2 RUN/SS PIN PULL-UP CURRENT ( 0.1 0 0 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 37361 G17 37361 G18
U U U PI FU CTIO S (UF/GN Package) ITH1/ITH2 (Pins 1, 8/Pins 4, 11):
Current Threshold and R = 10Ω, C = 1µF) is suggested to minimize noise pickup, Error Amplifier Compensation Point. Nominal operating especially in high load current applications. range on these pins is from 0.7V to 2V. The voltage on
TRACK (Pin 6/Pin 9):
Tracking Input for Second Control- these pins determines the threshold of the main current ler. Allows the start-up of VOUT2 to “track” that of VOUT1 comparator. according to a ratio established by a resistor divider on
FREQ (Pin 3/Pin 6):
Frequency Filter and Adjust Pin. Nor- VOUT1 connected to the TRACK pin. For one-to-one track- mally, when spread spectrum operation is enabled (SSDIS ing of VOUT1 and VOUT2 during start-up, a resistor divider = GND), a capacitor (1nF to 4.7nF) is connected from this with a ratio equal to those connected to VFB2 from VOUT2 pin to SGND or VIN to filter and smooth the changes in fre- should be used to connect to TRACK from VOUT1. quency of the LTC3736-1’s internal oscillator.
PGOOD(Pin 9/Pin 12):
Power Good Output Voltage Moni- When spread spectrum operation is disabled (SSDIS = VIN), tor Open-Drain Logic Output. This pin is pulled to ground this pin serves as a frequency adjust pin. In this mode, tying when the voltage on either feedback pin (VFB1, VFB2) is not this pin to GND selects 300kHz operation; tying this pin to within ±13.3% of its nominal set point. VIN selects 750kHz operation; floating this pin selects
PGND (Pins 12, 16, 20, 25/Pins 15, 19, 23):
Power Ground. 550kHz operation. These pins serve as the ground connection for the gate When spread spectrum operation is enabled (SSDIS = drivers and the negative input to the reverse current com- GND), an external voltage between approximately 0.7V and parators. The Exposed Pad (UF package) must be soldered 1.5V may be applied to this pin to adjust (in an analog to PCB ground. manner) the LTC3736-1’s frequency.
RUN/SS (Pin 14/Pin 17):
Run Control Input and Optional
SGND (Pin 4/Pin 7):
Small-Signal Ground. This pin serves External Soft-Start Input. Forcing this pin below 0.65V shuts as the ground connection for most internal circuits. down the chip (both channels). Driving this pin to VIN or
V
releasing this pin enables the chip, using the chip’s inter-
IN (Pin 5/Pin 8):
Chip Signal Power Supply. This pin powers the entire chip except for the gate drivers. Externally nal soft-start. An external soft-start can be programmed by filtering this pin with a lowpass RC network (e.g., connecting a capacitor between this pin and ground. 37361f 6
