LTC3802_15 Datasheet, PDF (8/28 Pages) Linear Technology – Dual 550kHz Synchronous 2-Phase DC/DC Controller with Programmable Up/Down Tracking

LTC3802
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Temperature
10
I_VCC
I_PVCC
(NO LOAD)
1
I_BOOST1
I_BOOST2
(NO LOAD)
0.1
I_VCC
SHUTDOWN
V_CC = V_PVCC = V_BOOST – V_SW = 5V
0.01
–50 –25 0 25 50 75 100 125
TEMPERATURE (°C)
3802 G26
Supply Current vs Supply Voltage
10
T_A = 25°C
I_VCC
I_PVCC (NO LOAD)
1
I_BOOST1, I_BOOST2
(NO LOAD)
0.1
I_VCC SHUTDOWN
0.01
3
3.5 4 4.5 5 5.5 6
SUPPLY VOLTAGE (V)
3802 G27
PI FU CTIO S (28-Pin SSOP/32-Pin QFN Package)
PV_CC (Pin 1/Pin 29): Driver Power Supply Input. PV_CC
provides power to the two BG drivers and must be con-
nected to an external voltage high enough to fully turn on
the external MOSFETs, QB1 and QB2. PV_CC requires at
least a 10µF bypass capacitor directly to PGND.
BG1 (Pin 2/Pin 30): Channel 1 Controller Bottom Gate
Drive. The BG1 pin drives the gate of the bottom N-channel
synchronous switch MOSFET, QB1. BG1 is designed to
drive typically up to 10,000pF of gate capacitance.
BOOST1 (Pin 3/Pin 31): Channel 1 Controller Top Gate
Driver Supply. BOOST1 should be bootstrapped to SW1
with a 0.1µF capacitor. An external Schottky diode from
PV_CC to BOOST1 creates a complete floating charge-
pumped supply at BOOST1. No other external supplies are
required.
TG1 (Pin 4/Pin 32): Channel 1 Controller Top Gate Drive.
The TG1 pin drives the top N-channel MOSFET with a
voltage swing equal to PV_CC superimposed on the switch
node voltage SW1. TG1 is designed to drive typically up to
6000pF of gate capacitance.
SW1 (Pin 5/Pin 1): Channel 1 Controller Switching Node.
Connect SW1 to the switching node of the channel 1
converter. When the bottom MOSFET QB1 turns on, the
current limit comparator and the burst comparator
monitor the voltage at SW1. If the voltage drop across
MOSFET QB1 is too large, the controller enters current
limit; if it is too small, the switcher enters Burst Mode
operation. See Current Limit and Burst Mode Applica-
tions Information.
PGND (Pin 6/Pins 2, 3, 23, 24): Power Ground. The BG
drivers return to this pin. Connect PGND to a high current
ground node in close proximity to the sources of external
MOSFETs QB1 and QB2 and the V_IN, PV_CC and V_OUT
bypass capacitors.
I_MAX1 (Pin 7/Pin 4): Channel 1 Controller Current Limit
Set. The I_MAX1 pin has an internal 10µA current source
pull-up, allowing the current limit and burst comparator
threshold to be programmed by a single external resistor
to SGND. See Current Limit and Burst Mode Applications
Information.
3802f
8