MAX1640_09 Datasheet, PDF (5/12 Pages) Maxim Integrated Products – Adjustable-Output, Switch-Mode Current Sources with Synchronous Rectifier

Adjustable-Output, Switch-Mode
Current Source with Synchronous Rectifier
____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 1, T_A = +25°C, unless otherwise noted.)
CURRENT-MODE CHANGE RESPONSE TIME
EXITING OFF MODE
A
A
0A
0V
B
B
2ms/div
V_IN = 12V, V_SET = 1V, R_LOAD = 4Ω, NO OUTPUT CAPACITOR
A: OUTPUT CURRENT, D0 = D1 = 0 1A/div
B: LOAD VOLTAGE, AC coupled, 500mV/div
20μs/div
V_IN = 12V, R_LOAD = 4Ω
A: D0 = D1 = 1 2V/div
B: OUTPUT CURRENT, 0.5A/div
______________________________________________________________Pin Description
PIN NAME
FUNCTION
1
LDOL
Internal, Ground-Referenced Low-Dropout Linear Regulator Output.
Bypass LDOL with a 0.1µF capacitor in parallel with a 4.7µF capacitor to GND.
Off-Time Select Input. A resistor (R_TOFF) connected from TOFF to GND programs the off-time for the hys-
2
TOFF teretic PWM step-down converter. This resistor also sets the period in duty-cycle mode. See Duty-Cycle
Mode and Programming the Off-Time.
3, 4 D1, D0 Digital Inputs. Select mode of operation (Table 1).
5
CC
Constant-Current Loop Compensation Input. Bypass CC with a 0.01µF capacitor to GND.
6
REF
Reference Voltage Output (V_REF = 2V). Bypass REF with a 0.1µF capacitor to GND.
7
SET
Current Select Input. Program the desired current level by applying a voltage at SET between 0V and V_REF,
(I = V_SET / 13.3R_SENSE). See Figure 2.
8
TERM
Maximum Output Voltage Termination Input. When V_TERM exceeds the reference voltage, the comparator
resets the internal PWM latch, shutting off the external P-channel FET.
9
GND Ground
10
CS-
Negative Current-Sense Comparator Input
11
CS+
Positive Current-Sense Comparator Input
12
PGND High-Current Ground Return for the output drivers
13
NDRV Gate Drive for an optional N-channel FET synchronous rectifier
14
PDRV Gate Drive for the P-channel FET
15
LDOH
Internal, Input-Referenced Low-Dropout Linear Regulator Output.
Bypass LDOH with a 0.33µF capacitor to IN.
16
IN
Power-Supply Input. Input of the internal, low-dropout linear regulators.
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