Datasheet LTC3770 (Analog Devices) - 7
| Hersteller | Analog Devices |
| Beschreibung | Fast No RSENSE Step-Down Synchronous Controller with Margining, Tracking and PLL |
| Seiten / Seite | 24 / 7 — TYPICAL PERFORMANCE CHARACTERISTICS. Current Limit Foldback. Ion Current … |
| Dateiformat / Größe | PDF / 273 Kb |
| Dokumentensprache | Englisch |
TYPICAL PERFORMANCE CHARACTERISTICS. Current Limit Foldback. Ion Current vs VIN. PIN FUNCTIONS (UH Package/G Package)
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LTC3770
TYPICAL PERFORMANCE CHARACTERISTICS Current Limit Foldback Ion Current vs VIN
160 140 VRNG = 1V RON = 82k 140 120 120 100 100 80 80 60 60 ION CURRENT (μA) 40 40 20 20 MAXIMUM CURRENT SENSE THRESHOLD (mV) 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0 5 10 15 20 25 30 35 VFB (V) INPUT VOLTAGE (V) 3770 G21 3770 G22
PIN FUNCTIONS (UH Package/G Package) VRNG (Pin 1/Pin 4):
Sense Voltage Range Input. The
MARGIN0 (Pin 6/Pin 9):
The LSB Logic Input for the voltage at this pin is ten times the nominal sense voltage Margining Function. Together with the MARGIN1 pin at maximum output current and can be set from 0.5V to determines whether the IC is in margin high, margin low, 2V by a resistive divider from INTVCC. The nominal sense or no margin state. This pin has a 50k internal pull-down voltage defaults to 50mV when this pin is tied to ground, resistor. 200mV when tied to INTVCC. Do not set this voltage
I
between 0.5V to ground or 2V to INTV
ON (Pin 7/Pin 10):
On-Time Current Input. Tie a resistor CC. from this pin to ground to set the one-shot timer current
VFB (Pin 2/Pin 5):
Error Amplifi er Feedback Input. This pin and thereby set the switching frequency. connects the error amplifi er input to an external resistive
V
divider from V
REFIN (Pin 8/Pin 11):
Error Amplifi er Reference Input. OUT. The voltage at this pin must be greater than 0.5V and
ITH (Pin 3/Pin 6):
Current Control Threshold and Error less than 1V. Amplifi er Compensation Point. The current comparator
V
threshold increases with this control voltage. The voltage
REFOUT (Pin 9/Pin 12):
Buffered Internal 0.6V Reference Output. The maximum current sinking limit is 50μA at ranges from 0V to 2.4V with 0.75V corresponding to zero this pin. Do not put a fi lter capacitor larger than 100pF sense voltage (zero current). on this pin.
SGND (Pin 4/Pin 7):
Signal Ground. All small-signal
MPGM (Pin 10/Pin 13):
Programmable Margining Input. components and compensation components should A resistor from this pin to ground sets the margining connect to this ground, which in turn connects to PGND current. This current, together with the resistor between at one point. the VREFOUT and VREFIN pins, determines the margining
MARGIN1 (Pin 5/Pin 8):
The MSB Logic Input for the voltage offset. Margining Function. Together with the MARGIN0 pin
TRACK/SS (Pin 11/Pin 14):
Output Voltage Tracking and determines whether the IC is in margin high, margin low, Soft-Start Input. When the IC is confi gured to be the or no margin state. This pin has a 50k internal pull-down master of two outputs, a capacitor to ground at this pin resistor. 3770fc 7
TYPICAL PERFORMANCE CHARACTERISTICS Current Limit Foldback Ion Current vs VIN
160 140 VRNG = 1V RON = 82k 140 120 120 100 100 80 80 60 60 ION CURRENT (μA) 40 40 20 20 MAXIMUM CURRENT SENSE THRESHOLD (mV) 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0 5 10 15 20 25 30 35 VFB (V) INPUT VOLTAGE (V) 3770 G21 3770 G22
PIN FUNCTIONS (UH Package/G Package) VRNG (Pin 1/Pin 4):
Sense Voltage Range Input. The
MARGIN0 (Pin 6/Pin 9):
The LSB Logic Input for the voltage at this pin is ten times the nominal sense voltage Margining Function. Together with the MARGIN1 pin at maximum output current and can be set from 0.5V to determines whether the IC is in margin high, margin low, 2V by a resistive divider from INTVCC. The nominal sense or no margin state. This pin has a 50k internal pull-down voltage defaults to 50mV when this pin is tied to ground, resistor. 200mV when tied to INTVCC. Do not set this voltage
I
between 0.5V to ground or 2V to INTV
ON (Pin 7/Pin 10):
On-Time Current Input. Tie a resistor CC. from this pin to ground to set the one-shot timer current
VFB (Pin 2/Pin 5):
Error Amplifi er Feedback Input. This pin and thereby set the switching frequency. connects the error amplifi er input to an external resistive
V
divider from V
REFIN (Pin 8/Pin 11):
Error Amplifi er Reference Input. OUT. The voltage at this pin must be greater than 0.5V and
ITH (Pin 3/Pin 6):
Current Control Threshold and Error less than 1V. Amplifi er Compensation Point. The current comparator
V
threshold increases with this control voltage. The voltage
REFOUT (Pin 9/Pin 12):
Buffered Internal 0.6V Reference Output. The maximum current sinking limit is 50μA at ranges from 0V to 2.4V with 0.75V corresponding to zero this pin. Do not put a fi lter capacitor larger than 100pF sense voltage (zero current). on this pin.
SGND (Pin 4/Pin 7):
Signal Ground. All small-signal
MPGM (Pin 10/Pin 13):
Programmable Margining Input. components and compensation components should A resistor from this pin to ground sets the margining connect to this ground, which in turn connects to PGND current. This current, together with the resistor between at one point. the VREFOUT and VREFIN pins, determines the margining
MARGIN1 (Pin 5/Pin 8):
The MSB Logic Input for the voltage offset. Margining Function. Together with the MARGIN0 pin
TRACK/SS (Pin 11/Pin 14):
Output Voltage Tracking and determines whether the IC is in margin high, margin low, Soft-Start Input. When the IC is confi gured to be the or no margin state. This pin has a 50k internal pull-down master of two outputs, a capacitor to ground at this pin resistor. 3770fc 7