Rainbow Electronics MAX1802 - Manual (Page 13)

MAX1802
Digital Camera Step-Down
Power Supply
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PIN NAME FUNCTION
17 COMP2
Compensation for Auxiliary Controller 2. Output of auxiliary controller 2 transconductance error
amplifier. Connect a series resistor and capacitor from COMP2 to GND to compensate the auxiliary
controller 2 control loop (see Compensation Design).
18 DCON2
Maximum Duty Cycle Control Input for Auxiliary Controller 2. Connect DCON2 to VL to set the default
maximum duty cycle. Connect a resistive voltage-divider from REF to DCON2 to set the maximum
duty cycle between 40% and 90%. Pull DCON2 below 300mV to turn the controller off.
19 DL2
External MOSFET Gate Drive Output for Auxiliary Controller 2. DL2 swings between VDDC and PGND
with 400mA (typ) drive current. Connect DL2 to the gate of the external switching N-channel MOSFET
for auxiliary controller 2.
20 DL3
External MOSFET Gate Drive Output for Auxiliary Controller 3. DL3 swings between VDDC and PGND
with 400mA (typ) drive current. Connect DL3 to the gate of the external switching N-channel MOSFET
for auxiliary controller 3.
21 COMP3
Compensation for Auxiliary Controller 3. Output of auxiliary controller 3 transconductance error
amplifier. Connect a series resistor and capacitor from COMP3 to GND to compensate the auxiliary
controller 3 control loop (see Compensation Design).
22 FB3
Feedback Input for Auxiliary Controller 3. Connect a feedback resistive voltage-divider from the
output of auxiliary controller 3 to FB3 to set the output voltage. Regulation voltage is V
REF (1.25V).
23 DCON3
Maximum Duty Cycle Control Input for Auxiliary Controller 3. Connect DCON3 to VL to set the default
maximum duty cycle. Connect a resistive voltage-divider from REF to DCON3 to set the maximum
duty cycle between 40% and 90%. Pull DCON3 below 300mV to turn the controller off.
24 ONC
Core Converter Enable Input. High level turns on the core converter. Connect ONC to VL to
automatically start the core converter.
25 PGND
Power Ground. Sources of internal N-channel MOSFET power switches. Connect PGND to GND as
close to the IC as possible.
26 LXC
Core Power Switching Node. Drains of the internal P- and N-channel MOSFET switches for the core
converter.
27 VDDC
Core DC-DC Converter Power Input. VDDC is connected to the source of the internal P-channel
MOSFET power switch for the core converter. VDDC is limited to 5.5V. For battery voltages greater
than 5.5V, connect VDDC to the main output. Bypass VDDC to PGND with a 1 µF or greater ceramic
capacitor.
28 VL
Internal Low-Voltage Bypass. The internal circuitry is powered from VL. An internal linear regulator
powers VL from VDDM when VDDC is less than 2.4V. When VDDC is greater than 2.4V, an internal
switch connects VL to VDDC. Bypass VL to GND with a 1.0
µF or greater ceramic capacitor.
29 COMPC
Compensation for Core Converter. Output of core transconductance error amplifier. Connect a series
resistor and capacitor to GND to compensate the core control loop (see Compensation Design).
30 FBC
Core DC-DC Converter Feedback Input. Connect a feedback resistive voltage-divider from the core
output to FBC to set the output voltage. Regulation voltage is V
REF (1.25V).
31 REF 1.25V Reference Output. Bypass REF to GND with a 0.1 µF or greater ceramic capacitor.
32 GND Analog Ground
Pin Description (continued)