MAX762CSA Maxim Integrated Products, MAX762CSA Datasheet - Page 7

• Manufacturer Part Number: MAX762CSA
• Description: IC CONV DC/DC 15V STEP UP 8SOIC
• Manufacturer: Maxim Integrated Products
• Type: Step-Up (Boost)r

Specifications of MAX762CSA

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 15V, 5 ~ 16.5 V
• Current - Output: 150mA
• Frequency - Switching: 300kHz
• Voltage - Input: 2 ~ 16.5 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Power - Output: 471mW
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Figure 1. Simple Block Diagram
The MAX761/MAX762 BiCMOS step-up switch-mode
power supplies provide fixed outputs of 12V and 15V,
respectively. They have a unique control scheme that
combines the advantages of pulse-frequency modulation
(low supply current) and pulse-width modulation (high
efficiency at high loads). The internal N-channel power
MOSFET allows 1A peak currents, increasing the output
current capability over previous pulse-frequency-modu-
lation (PFM) devices. Figure 1 shows the MAX761/
MAX762 block diagram.
The MAX761/MAX762 offer three main improvements
over prior solutions: (1) the converters operate with tiny
surface-mount inductors (less than 5mm diameter)
________________Detailed Description
REF
LBI
_______________________________________________________________________________________
12V/15V or Adjustable, High-Efficiency,
TRIG
ONE-SHOT
LBI
Q
Operating Principle
CURRENT CONTROL
S
Q
CIRCUITRY
ONE-SHOT
Low I
R
LBO
TRIG
N
CURRENT
COMPARATOR
Q
V+
OSCILLATOR
0.2V
LOW INPUT
REFERENCE
VOLTAGE
Q
1.5V
, Step-Up DC-DC Converters
100mV
FB
because of their 300kHz switching frequency, (2) the
current-limited PFM control scheme allows 86% efficien-
cies over a wide range of load currents, and (3) the max-
imum supply current is only 110µA.
Figures 2 and 3 show the standard application circuits
for bootstrapped and non-bootstrapped modes. In boot-
strapped mode, the IC is powered from the output
(V
bootstrapped circuit is different from the V+ current the
chip consumes. The voltage applied to the gate of the
internal N-channel FET is switched from V
providing more switch-gate drive and increasing the effi-
ciency of the DC-DC converter compared with non-boot-
strapped operation.
GND
OUT
0.1V
ERROR
COMPARATOR
Bootstrapped/Non-Bootstrapped Modes
). In other words, the current needed to power the
DUAL-MODE
COMPARATOR
UNDER VOLTAGE
COMPARATOR
N
N
MAX761
MAX762
2.5V
OUT
to ground,
V+
LX
7