MAX5051 Maxim Integrated Products, MAX5051 Datasheet - Page 9

• Manufacturer Part Number: MAX5051
• Description: Parallelable Clamped Two-Switch Power-Supply Controller IC
• Manufacturer: Maxim Integrated Products

(V
4.7µF, T
AVIN
PIN
10
11
12
1
2
3
4
5
6
7
8
9
= V
A
= +25°C, unless otherwise noted.)
PVIN
SYNCOUT
RCOSC
= 12V, V
LXVDD
110
105
100
NAME
COMP
REG5
REG9
RCFF
95
90
85
80
75
70
65
60
CON
PVIN
CSS
STT
FB
-50
_______________________________________________________________________________________
50mV OVERDRIVE
CON TO DRVL PROPAGATION DELAY
-25
UVLO
Osci l l ator Fr eq uency S et Inp ut. C onnect a r esi stor fr om RC OS C to RE G5 and a cap aci tor fr om RC OS C to GN D
to set the osci l l ator fr eq uency. S w i tchi ng fr eq uency i s 1/2 the fr eq uency of the saw tooth si g nal at RC OS C .
Synchronization Output. Synchronization signal to drive SYNCIN of a second MAX5051, if used.
Feed-Forward Input. Connect a resistor from RCFF to AVIN and a capacitor from RCFF to GND. This is
the PWM ramp.
PWM Comparator Noninverting Input. Connect CON to the optocoupler output for isolated applications,
or to COMP for nonisolated applications.
Soft-Start and Reference. Connect a 0.01µF or greater capacitor from CSS to GND. The 1.24V reference
voltage appears across this capacitor.
Internal Error Amplifier Output
Feedback Input. Inverting input of the internal error amplifier. The soft-started reference is connected to
the noninverting input of this amplifier.
5V Linear Regulator Output. Bypass REG5 to GND with a 4.7µF ceramic capacitor.
9V Linear Regulator Output. Bypass REG9 to GND with a 4.7µF ceramic capacitor.
Regulator Voltage Input. Voltage input to the internal 5V and 9V linear regulators. A high-value resistor
connected from the input supply to PVIN provides the necessary current to charge up the startup
capacitor, and the 400µA standby current required by the MAX5051. After startup, the output of a tertiary
winding is used to provide continued bias to the controller.
Startup Threshold Input. Leave STT floating for a default startup voltage of 24V at PVIN. STT can be
modified by connecting external resistors. For high accuracy, choose external resistors with 50kΩ or less
impedance looking back into the divider.
Supply Input for the Secondary-Side Synchronous Pulse Transformer or Optocoupler Driver. LXVDD is
normally connected to REG5.
vs. TEMPERATURE
0
TEMPERATURE (°C)
= V
25
STT
= 3V, V
Parallelable, Clamped Two-Switch
50
75
CON
100
Typical Operating Characteristics (continued)
= 3V, R
125
RCOSC
Power-Supply Controller IC
= 24kΩ, C
FUNCTION
CSS
= 10nF, C
150
140
130
120
110
100
90
80
-50
PROPAGATION DELAY vs. TEMPERATURE
50mV OVERDRIVE
-25
CS CURRENT LIMIT TO DRVH
RCOSC
0
TEMPERATURE (°C)
= 100pF, C
25
50
Pin Description
75
REG9
www.DataSheet4U.com
100
= 4.7µF, C
125
REG5
=
9